text:
Star
From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
This article is about the astronomical object. For other uses, see Star (disambiguation).
A star-forming region in the Large Magellanic Cloud
False-color imagery of the Sun, a G-type main-sequence star, the closest to Earth
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the stars in the Universe, including all stars outside our galaxy, the Milky Way, are invisible to the naked eye from Earth. Indeed, most are invisible from Earth even through the most powerful telescopes.
For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime, and for some stars by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, its luminosity, and spectrum respectively. The total mass of a star is the main factor that determines its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities produces a plot known as a Hertzsprung–Russell diagram (H–R diagram). Plotting a particular star on that diagram allows the age and evolutionary state of that star to be determined.
A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. When the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process.[1] The remainder of the star's interior carries energy away from the core through a combination of radiative and convective heat transfer processes. The star's internal pressure prevents it from collapsing further under its own gravity. A star with mass greater than 0.4 times the Sun's will expand to become a red giant when the hydrogen fuel in its core is exhausted.[2] In some cases, it will fuse heavier elements at the core or in shells around the core. As the star expands it throws a part of its mass, enriched with those heavier elements, into the interstellar environment, to be recycled later as new stars.[3] Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or if it is sufficiently massive a black hole.
Binary and multi-star systems consist of two or more stars that are gravitationally bound and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution.[4] Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.
Contents
1 Observation history
2 Designations
3 Units of measurement
4 Formation and evolution
4.1 Star formation
4.2 Main sequence
4.3 Post–main sequence
4.3.1 Massive stars
4.3.2 Collapse
4.3.3 Binary stars
5 Distribution
6 Characteristics
6.1 Age
6.2 Chemical composition
6.3 Diameter
6.4 Kinematics
6.5 Magnetic field
6.6 Mass
6.7 Rotation
6.8 Temperature
7 Radiation
7.1 Luminosity
7.2 Magnitude
8 Classification
9 Variable stars
10 Structure
11 Nuclear fusion reaction pathways
12 See also
13 References
14 Further reading
15 External links
Observation history
People have seen patterns in the stars since ancient times.[5] This 1690 depiction of the constellation of Leo, the lion, is by Johannes Hevelius.[6]
The constellation of Leo as it can be seen by the naked eye. Lines have been added.
Historically, stars have been important to civilizations throughout the world. They have been part of religious practices and used for celestial navigation and orientation. Many ancient astronomers believed that stars were permanently affixed to a heavenly sphere and that they were immutable. By convention, astronomers grouped stars into constellations and used them to track the motions of the planets and the inferred position of the Sun.[5] The motion of the Sun against the background stars (and the horizon) was used to create calendars, which could be used to regulate agricultural practices.[7] The Gregorian calendar, currently used nearly everywhere in the world, is a solar calendar based on the angle of the Earth's rotational axis relative to its local star, the Sun.
The oldest accurately dated star chart was the result of ancient Egyptian astronomy in 1534 BC.[8] The earliest known star catalogues were compiled by the ancient Babylonian astronomers of Mesopotamia in the late 2nd millennium BC, during the Kassite Period (ca. 1531–1155 BC).[9]
The first star catalogue in Greek astronomy was created by Aristillus in approximately 300 BC, with the help of Timocharis.[10] The star catalog of Hipparchus (2nd century BC) included 1020 stars, and was used to assemble Ptolemy's star catalogue.[11] Hipparchus is known for the discovery of the first recorded nova (new star).[12] Many of the constellations and star names in use today derive from Greek astronomy.
In spite of the apparent immutability of the heavens, Chinese astronomers were aware that new stars could appear.[13] In 185 AD, they were the first to observe and write about a supernova, now known as the SN 185.[14] The brightest stellar event in recorded history was the SN 1006 supernova, which was observed in 1006 and written about by the Egyptian astronomer Ali ibn Ridwan and several Chinese astronomers.[15] The SN 1054 supernova, which gave birth to the Crab Nebula, was also observed by Chinese and Islamic astronomers.[16][17][18]
Medieval Islamic astronomers gave Arabic names to many stars that are still used today and they invented numerous astronomical instruments that could compute the positions of the stars. They built the first large observatory research institutes, mainly for the purpose of producing Zij star catalogues.[19] Among these, the Book of Fixed Stars (964) was written by the Persian astronomer Abd al-Rahman al-Sufi, who observed a number of stars, star clusters (including the Omicron Velorum and Brocchi's Clusters) and galaxies (including the Andromeda Galaxy).[20] According to A. Zahoor, in the 11th century, the Persian polymath scholar Abu Rayhan Biruni described the Milky Way galaxy as a multitude of fragments having the properties of nebulous stars, and also gave the latitudes of various stars during a lunar eclipse in 1019.[21]
According to Josep Puig, the Andalusian astronomer Ibn Bajjah proposed that the Milky Way was made up of many stars that almost touched one another and appeared to be a continuous image due to the effect of refraction from sublunary material, citing his observation of the conjunction of Jupiter and Mars on 500 AH (1106/1107 AD) as evidence.[22] Early European astronomers such as Tycho Brahe identified new stars in the night sky (later termed novae), suggesting that the heavens were not immutable. In 1584, Giordano Bruno suggested that the stars were like the Sun, and may have other planets, possibly even Earth-like, in orbit around them,[23] an idea that had been suggested earlier by the ancient Greek philosophers, Democritus and Epicurus,[24] and by medieval Islamic cosmologists[25] such as Fakhr al-Din al-Razi.[26] By the following century, the idea of the stars being the same as the Sun was reaching a consensus among astronomers. To explain why these stars exerted no net gravitational pull on the Solar System, Isaac Newton suggested that the stars were equally distributed in every direction, an idea prompted by the theologian Richard Bentley.[27]
The Italian astronomer Geminiano Montanari recorded observing variations in luminosity of the star Algol in 1667. Edmond Halley published the first measurements of the proper motion of a pair of nearby "fixed" stars, demonstrating that they had changed positions since the time of the ancient Greek astronomers Ptolemy and Hipparchus.[23]
William Herschel was the first astronomer to attempt to determine the distribution of stars in the sky. During the 1780s, he established a series of gauges in 600 directions and counted the stars observed along each line of sight. From this he deduced that the number of stars steadily increased toward one side of the sky, in the direction of the Milky Way core. His son John Herschel repeated this study in the southern hemisphere and found a corresponding increase in the same direction.[28] In addition to his other accomplishments, William Herschel is also noted for his discovery that some stars do not merely lie along the same line of sight, but are also physical companions that form binary star systems.
The science of stellar spectroscopy was pioneered by Joseph von Fraunhofer and Angelo Secchi. By comparing the spectra of stars such as Sirius to the Sun, they found differences in the strength and number of their absorption lines—the dark lines in stellar spectra caused by the atmosphere's absorption of specific frequencies. In 1865, Secchi began classifying stars into spectral types.[29] However, the modern version of the stellar classification scheme was developed by Annie J. Cannon during the 1900s.
Alpha Centauri A and B over limb of Saturn
The first direct measurement of the distance to a star (61 Cygni at 11.4 light-years) was made in 1838 by Friedrich Bessel using the parallax technique. Parallax measurements demonstrated the vast separation of the stars in the heavens.[23] Observation of double stars gained increasing importance during the 19th century. In 1834, Friedrich Bessel observed changes in the proper motion of the star Sirius and inferred a hidden companion. Edward Pickering discovered the first spectroscopic binary in 1899 when he observed the periodic splitting of the spectral lines of the star Mizar in a 104-day period. Detailed observations of many binary star systems were collected by astronomers such as Friedrich Georg Wilhelm von Struve and S. W. Burnham, allowing the masses of stars to be determined from computation of orbital elements. The first solution to the problem of deriving an orbit of binary stars from telescope observations was made by Felix Savary in 1827.[30] The twentieth century saw increasingly rapid advances in the scientific study of stars. The photograph became a valuable astronomical tool. Karl Schwarzschild discovered that the color of a star and, hence, its temperature, could be determined by comparing the visual magnitude against the photographic magnitude. The development of the photoelectric photometer allowed precise measurements of magnitude at multiple wavelength intervals. In 1921 Albert A. Michelson made the first measurements of a stellar diameter using an interferometer on the Hooker telescope at Mount Wilson Observatory.[31]
Important theoretical work on the physical structure of stars occurred during the first decades of the twentieth century. In 1913, the Hertzsprung-Russell diagram was developed, propelling the astrophysical study of stars. Successful models were developed to explain the interiors of stars and stellar evolution. Cecilia Payne-Gaposchkin first proposed that stars were made primarily of hydrogen and helium in her 1925 PhD thesis.[32] The spectra of stars were further understood through advances in quantum physics. This allowed the chemical composition of the stellar atmosphere to be determined.[33]
With the exception of supernovae, individual stars have primarily been observed in the Local Group,[34] and especially in the visible part of the Milky Way (as demonstrated by the detailed star catalogues available for our galaxy).[35] But some stars have been observed in the M100 galaxy of the Virgo Cluster, about 100 million light years from the Earth.[36] In the Local Supercluster it is possible to see star clusters, and current telescopes could in principle observe faint individual stars in the Local Group[37] (see Cepheids). However, outside the Local Supercluster of galaxies, neither individual stars nor clusters of stars have been observed. The only exception is a faint image of a large star cluster containing hundreds of thousands of stars located at a distance of one billion light years[38]—ten times further than the most distant star cluster previously observed.
In February 2018, astronomers reported, for the first time, a signal of the reionization epoch, an indirect detection of light from the earliest stars formed - about 180 million years after the Big Bang.[39]
In April, 2018, astronomers reported the detection of the most distant "ordinary" (i.e., main sequence) star, named Icarus (formally, MACS J1149 Lensed Star 1), at 9 billion light-years away from Earth.[40][41]
In May 2018, astronomers reported the detection of the most distant oxygen ever detected in the Universe - and the most distant galaxy every observed by Atacama Large Millimeter Array or the Very Large Telescope - with the team inferring that the signal was emitted 13.3 billion years ago (or 500 million years after the Big Bang. They found that the observed brightness of the galaxy is well-explained by a model where the onset of star formation corresponds to only 250 million years after the Universe began, corresponding to a redshift of about 15.[42]
Designations
Main articles: Stellar designation, Astronomical naming conventions, and Star catalogue
The concept of a constellation was known to exist during the Babylonian period. Ancient sky watchers imagined that prominent arrangements of stars formed patterns, and they associated these with particular aspects of nature or their myths. Twelve of these formations lay along the band of the ecliptic and these became the basis of astrology.[43] Many of the more prominent individual stars were also given names, particularly with Arabic or Latin designations.
As well as certain constellations and the Sun itself, individual stars have their own myths.[44] To the Ancient Greeks, some "stars", known as planets (Greek πλανήτης (planētēs), meaning "wanderer"), represented various important deities, from which the names of the planets Mercury, Venus, Mars, Jupiter and Saturn were taken.[44] (Uranus and Neptune were also Greek and Roman gods, but neither planet was known in Antiquity because of their low brightness. Their names were assigned by later astronomers.)
Circa 1600, the names of the constellations were used to name the stars in the corresponding regions of the sky. The German astronomer Johann Bayer created a series of star maps and applied Greek letters as designations to the stars in each constellation. Later a numbering system based on the star's right ascension was invented and added to John Flamsteed's star catalogue in his book "Historia coelestis Britannica" (the 1712 edition), whereby this numbering system came to be called Flamsteed designation or Flamsteed numbering.[45][46]
The only internationally recognized authority for naming celestial bodies is the International Astronomical Union (IAU).[47] The International Astronomical Union maintains the Working Group on Star Names (WGSN)[48] which catalogs and standardizes proper names for stars. A number of private companies sell names of stars, which the British Library calls an unregulated commercial enterprise.[49][50] The IAU has disassociated itself from this commercial practice, and these names are neither recognized by the IAU, professional astronomers, nor the amateur astronomy community.[51] One such star-naming company is the International Star Registry, which, during the 1980s, was accused of deceptive practice for making it appear that the assigned name was official. This now-discontinued ISR practice was informally labeled a scam and a fraud,[52][53][54][55] and the New York City Department of Consumer Affairs issued a violation against ISR for engaging in a deceptive trade practice.[56][57]
Units of measurement
Although stellar parameters can be expressed in SI units or CGS units, it is often most convenient to express mass, luminosity, and radii in solar units, based on the characteristics of the Sun. In 2015, the IAU defined a set of nominal solar values (defined as SI constants, without uncertainties) which can be used for quoting stellar parameters:
nominal solar luminosity: L⊙ = 3.828 × 1026 W [58]
nominal solar radius R⊙ = 6.957 × 108 m [58]
The solar mass M⊙ was not explicitly defined by the IAU due to the large relative uncertainty (10−4) of the Newtonian gravitational constant G. However, since the product of the Newtonian gravitational constant and solar mass together (GM⊙) has been determined to much greater precision, the IAU defined the nominal solar mass parameter to be:
nominal solar mass parameter: GM⊙ = 1.3271244 × 1020 m3 s−2 [58]
However, one can combine the nominal solar mass parameter with the most recent (2014) CODATA estimate of the Newtonian gravitational constant G to derive the solar mass to be approximately 1.9885 × 1030 kg. Although the exact values for the luminosity, radius, mass parameter, and mass may vary slightly in the future due to observational uncertainties, the 2015 IAU nominal constants will remain the same SI values as they remain useful measures for quoting stellar parameters.
Large lengths, such as the radius of a giant star or the semi-major axis of a binary star system, are often expressed in terms of the astronomical unit — approximately equal to the mean distance between the Earth and the Sun (150 million km or approximately 93 million miles). In 2012, the IAU defined the astronomical constant to be an exact length in meters: 149,597,870,700 m.[58]
Formation and evolution
Stellar evolution of low-mass (left cycle) and high-mass (right cycle) stars, with examples in italics
Main article: Stellar evolution
Stars condense from regions of space of higher matter density, yet those regions are less dense than within a vacuum chamber. These regions – known as molecular clouds – consist mostly of hydrogen, with about 23 to 28 percent helium and a few percent heavier elements. One example of such a star-forming region is the Orion Nebula.[59] Most stars form in groups of dozens to hundreds of thousands of stars.[60] Massive stars in these groups may powerfully illuminate those clouds, ionizing the hydrogen, and creating H II regions. Such feedback effects, from star formation, may ultimately disrupt the cloud and prevent further star formation.
All stars spend the majority of their existence as main sequence stars, fueled primarily by the nuclear fusion of hydrogen into helium within their cores. However, stars of different masses have markedly different properties at various stages of their development. The ultimate fate of more massive stars differs from that of less massive stars, as do their luminosities and the impact they have on their environment. Accordingly, astronomers often group stars by their mass:[61]
Very low mass stars, with masses below 0.5 M☉, are fully convective and distribute helium evenly throughout the whole star while on the main sequence. Therefore, they never undergo shell burning, never become red giants, which cease fusing and become helium white dwarfs and slowly cool after exhausting their hydrogen.[62] However, as the lifetime of 0.5 M☉ stars is longer than the age of the universe, no such star has yet reached the white dwarf stage.
Low mass stars (including the Sun), with a mass between 0.5 M☉ and 1.8–2.5 M☉ depending on composition, do become red giants as their core hydrogen is depleted and they begin to burn helium in core in a helium flash; they develop a degenerate carbon-oxygen core later on the asymptotic giant branch; they finally blow off their outer shell as a planetary nebula and leave behind their core in the form of a white dwarf.
Intermediate-mass stars, between 1.8–2.5 M☉ and 5–10 M☉, pass through evolutionary stages similar to low mass stars, but after a relatively short period on the red giant branch they ignite helium without a flash and spend an extended period in the red clump before forming a degenerate carbon-oxygen core.
Massive stars generally have a minimum mass of 7–10 M☉ (possibly as low as 5–6 M☉). After exhausting the hydrogen at the core these stars become supergiants and go on to fuse elements heavier than helium. They end their lives when their cores collapse and they explode as supernovae.
Star formation
Main article: Star formation
The formation of a star begins with gravitational instability within a molecular cloud, caused by regions of higher density – often triggered by compression of clouds by radiation from massive stars, expanding bubbles in the interstellar medium, the collision of different molecular clouds, or the collision of galaxies (as in a starburst galaxy).[63][64] When a region reaches a sufficient density of matter to satisfy the criteria for Jeans instability, it begins to collapse under its own gravitational force.[65]
Artist's conception of the birth of a star within a dense molecular cloud.
As the cloud collapses, individual conglomerations of dense dust and gas form "Bok globules". As a globule collapses and the density increases, the gravitational energy converts into heat and the temperature rises. When the protostellar cloud has approximately reached the stable condition of hydrostatic equilibrium, a protostar forms at the core.[66] These pre-main-sequence stars are often surrounded by a protoplanetary disk and powered mainly by the conversion of gravitational energy. The period of gravitational contraction lasts about 10 to 15 million years.
A cluster of approximately 500 young stars lies within the nearby W40 stellar nursery.
Early stars of less than 2 M☉ are called T Tauri stars, while those with greater mass are Herbig Ae/Be stars. These newly formed stars emit jets of gas along their axis of rotation, which may reduce the angular momentum of the collapsing star and result in small patches of nebulosity known as Herbig–Haro objects.[67][68] These jets, in combination with radiation from nearby massive stars, may help to drive away the surrounding cloud from which the star was formed.[69]
Early in their development, T Tauri stars follow the Hayashi track—they contract and decrease in luminosity while remaining at roughly the same temperature. Less massive T Tauri stars follow this track to the main sequence, while more massive stars turn onto the Henyey track.
Most stars are observed to be members of binary star systems, and the properties of those binaries are the result of the conditions in which they formed.[70] A gas cloud must lose its angular momentum in order to collapse and form a star. The fragmentation of the cloud into multiple stars distributes some of that angular momentum. The primordial binaries transfer some angular momentum by gravitational interactions during close encounters with other stars in young stellar clusters. These interactions tend to split apart more widely separated (soft) binaries while causing hard binaries to become more tightly bound. This produces the separation of binaries into their two observed populations distributions.
Main sequence
Main article: Main sequence
Stars spend about 90% of their existence fusing hydrogen into helium in high-temperature and high-pressure reactions near the core. Such stars are said to be on the main sequence, and are called dwarf stars. Starting at zero-age main sequence, the proportion of helium in a star's core will steadily increase, the rate of nuclear fusion at the core will slowly increase, as will the star's temperature and luminosity.[71] The Sun, for example, is estimated to have increased in luminosity by about 40% since it reached the main sequence 4.6 billion (4.6 × 109) years ago.[72]
Every star generates a stellar wind of particles that causes a continual outflow of gas into space. For most stars, the mass lost is negligible. The Sun loses 10−14 M☉ every year,[73] or about 0.01% of its total mass over its entire lifespan. However, very massive stars can lose 10−7 to 10−5 M☉ each year, significantly affecting their evolution.[74] Stars that begin with more than 50 M☉ can lose over half their total mass while on the main sequence.[75]
An example of a Hertzsprung–Russell diagram for a set of stars that includes the Sun (center). (See "Classification" below.)
The time a star spends on the main sequence depends primarily on the amount of fuel it has and the rate at which it fuses it. The Sun is expected to live 10 billion (1010) years. Massive stars consume their fuel very rapidly and are short-lived. Low mass stars consume their fuel very slowly. Stars less massive than 0.25 M☉, called red dwarfs, are able to fuse nearly all of their mass while stars of about 1 M☉ can only fuse about 10% of their mass. The combination of their slow fuel-consumption and relatively large usable fuel supply allows low mass stars to last about one trillion (1012) years; the most extreme of 0.08 M☉) will last for about 12 trillion years. Red dwarfs become hotter and more luminous as they accumulate helium. When they eventually run out of hydrogen, they contract into a white dwarf and decline in temperature.[62] However, since the lifespan of such stars is greater than the current age of the universe (13.8 billion years), no stars under about 0.85 M☉[76] are expected to have moved off the main sequence.
Besides mass, the elements heavier than helium can play a significant role in the evolution of stars. Astronomers label all elements heavier than helium "metals", and call the chemical concentration of these elements in a star, its metallicity. A star's metallicity can influence the time the star takes to burn its fuel, and controls the formation of its magnetic fields,[77] which affects the strength of its stellar wind.[78] Older, population II stars have substantially less metallicity than the younger, population I stars due to the composition of the molecular clouds from which they formed. Over time, such clouds become increasingly enriched in heavier elements as older stars die and shed portions of their atmospheres.
Post–main sequence
Main articles: Subgiant, Red giant, Horizontal branch, Red clump, and Asymptotic giant branch
As stars of at least 0.4 M☉[2] exhaust their supply of hydrogen at their core, they start to fuse hydrogen in a shell outside the helium core. Their outer layers expand and cool greatly as they form a red giant. In about 5 billion years, when the Sun enters the helium burning phase, it will expand to a maximum radius of roughly 1 astronomical unit (150 million kilometres), 250 times its present size, and lose 30% of its current mass.[72][79]
As the hydrogen shell burning produces more helium, the core increases in mass and temperature. In a red giant of up to 2.25 M☉, the mass of the helium core becomes degenerate prior to helium fusion. Finally, when the temperature increases sufficiently, helium fusion begins explosively in what is called a helium flash, and the star rapidly shrinks in radius, increases its surface temperature, and moves to the horizontal branch of the HR diagram. For more massive stars, helium core fusion starts before the core becomes degenerate, and the star spends some time in the red clump, slowly burning helium, before the outer convective envelope collapses and the star then moves to the horizontal branch.[4]
After the star has fused the helium of its core, the carbon product fuses producing a hot core with an outer shell of fusing helium. The star then follows an evolutionary path called the asymptotic giant branch (AGB) that parallels the other described red giant phase, but with a higher luminosity. The more massive AGB stars may undergo a brief period of carbon fusion before the core becomes degenerate.
Massive stars
Main articles: Supergiant star, Hypergiant, and Wolf–Rayet star
During their helium-burning phase, a star of more than 9 solar masses expands to form first a blue and then a red supergiant. Particularly massive stars may evolve to a Wolf-Rayet star, characterised by spectra dominated by emission lines of elements heavier than hydrogen, which have reached the surface due to strong convection and intense mass loss.
When helium is exhausted at the core of a massive star, the core contracts and the temperature and pressure rises enough to fuse carbon (see Carbon-burning process). This process continues, with the successive stages being fueled by neon (see neon-burning process), oxygen (see oxygen-burning process), and silicon (see silicon-burning process). Near the end of the star's life, fusion continues along a series of onion-layer shells within a massive star. Each shell fuses a different element, with the outermost shell fusing hydrogen; the next shell fusing helium, and so forth.[80]
The final stage occurs when a massive star begins producing iron. Since iron nuclei are more tightly bound than any heavier nuclei, any fusion beyond iron does not produce a net release of energy. To a very limited degree such a process proceeds, but it consumes energy. Likewise, since they are more tightly bound than all lighter nuclei, such energy cannot be released by fission.[81]
Collapse
As a star's core shrinks, the intensity of radiation from that surface increases, creating such radiation pressure on the outer shell of gas that it will push those layers away, forming a planetary nebula. If what remains after the outer atmosphere has been shed is less than 1.4 M☉, it shrinks to a relatively tiny object about the size of Earth, known as a white dwarf. White dwarfs lack the mass for further gravitational compression to take place.[82] The electron-degenerate matter inside a white dwarf is no longer a plasma, even though stars are generally referred to as being spheres of plasma. Eventually, white dwarfs fade into black dwarfs over a very long period of time.
The Crab Nebula, remnants of a supernova that was first observed around 1050 AD
In massive stars, fusion continues until the iron core has grown so large (more than 1.4 M☉) that it can no longer support its own mass. This core will suddenly collapse as its electrons are driven into its protons, forming neutrons, neutrinos, and gamma rays in a burst of electron capture and inverse beta decay. The shockwave formed by this sudden collapse causes the rest of the star to explode in a supernova. Supernovae become so bright that they may briefly outshine the star's entire home galaxy. When they occur within the Milky Way, supernovae have historically been observed by naked-eye observers as "new stars" where none seemingly existed before.[83]
A supernova explosion blows away the star's outer layers, leaving a remnant such as the Crab Nebula.[83] The core is compressed into a neutron star, which sometimes manifests itself as a pulsar or X-ray burster. In the case of the largest stars, the remnant is a black hole greater than 4 M☉.[84] In a neutron star the matter is in a state known as neutron-degenerate matter, with a more exotic form of degenerate matter, QCD matter, possibly present in the core. Within a black hole, the matter is in a state that is not currently understood.
The blown-off outer layers of dying stars include heavy elements, which may be recycled during the formation of new stars. These heavy elements allow the formation of rocky planets. The outflow from supernovae and the stellar wind of large stars play an important part in shaping the interstellar medium.[83]
Binary stars
The post–main-sequence evolution of binary stars may be significantly different from the evolution of single stars of the same mass. If stars in a binary system are sufficiently close, when one of the stars expands to become a red giant it may overflow its Roche lobe, the region around a star where material is gravitationally bound to that star, leading to transfer of material to the other. When the Roche lobe is violated, a variety of phenomena can result, including contact binaries, common-envelope binaries, cataclysmic variables, and type Ia supernovae.
Distribution
A white dwarf star in orbit around Sirius (artist's impression).
Stars are not spread uniformly across the universe, but are normally grouped into galaxies along with interstellar gas and dust. A typical galaxy contains hundreds of billions of stars, and there are more than 100 billion (1011) galaxies in the observable universe.[85] In 2010, one estimate of the number of stars in the observable universe was 300 sextillion (3 × 1023).[86][87] While it is often believed that stars only exist within galaxies, intergalactic stars have been discovered.[88]
A multi-star system consists of two or more gravitationally bound stars that orbit each other. The simplest and most common multi-star system is a binary star, but systems of three or more stars are also found. For reasons of orbital stability, such multi-star systems are often organized into hierarchical sets of binary stars.[89] Larger groups called star clusters also exist. These range from loose stellar associations with only a few stars, up to enormous globular clusters with hundreds of thousands of stars. Such systems orbit their host galaxy.
It has been a long-held assumption that the majority of stars occur in gravitationally bound, multiple-star systems. This is particularly true for very massive O and B class stars, where 80% of the stars are believed to be part of multiple-star systems. The proportion of single star systems increases with decreasing star mass, so that only 25% of red dwarfs are known to have stellar companions. As 85% of all stars are red dwarfs, most stars in the Milky Way are likely single from birth.[90]
This view contains blue stars known as "Blue stragglers", for their apparent location on the Hertzsprung–Russell diagram
The nearest star to the Earth, apart from the Sun, is Proxima Centauri, which is 39.9 trillion kilometres, or 4.2 light-years. Travelling at the orbital speed of the Space Shuttle (8 kilometres per second—almost 30,000 kilometres per hour), it would take about 150,000 years to arrive.[91] This is typical of stellar separations in galactic discs.[92] Stars can be much closer to each other in the centres of galaxies and in globular clusters, or much farther apart in galactic halos.
Due to the relatively vast distances between stars outside the galactic nucleus, collisions between stars are thought to be rare. In denser regions such as the core of globular clusters or the galactic center, collisions can be more common.[93] Such collisions can produce what are known as blue stragglers. These abnormal stars have a higher surface temperature than the other main sequence stars with the same luminosity of the cluster to which it belongs.[94]
Characteristics
Almost everything about a star is determined by its initial mass, including such characteristics as luminosity, size, evolution, lifespan, and its eventual fate.
Some of the well-known stars with their apparent colors and relative sizes.
Age
Main article: Stellar age estimation
Most stars are between 1 billion and 10 billion years old. Some stars may even be close to 13.8 billion years old—the observed age of the universe. The oldest star yet discovered, HD 140283, nicknamed Methuselah star, is an estimated 14.46 ± 0.8 billion years old.[95] (Due to the uncertainty in the value, this age for the star does not conflict with the age of the Universe, determined by the Planck satellite as 13.799 ± 0.021).[95][96]
The more massive the star, the shorter its lifespan, primarily because massive stars have greater pressure on their cores, causing them to burn hydrogen more rapidly. The most massive stars last an average of a few million years, while stars of minimum mass (red dwarfs) burn their fuel very slowly and can last tens to hundreds of billions of years.[97][98]
Chemical composition
See also: Metallicity and Molecules in stars
When stars form in the present Milky Way galaxy they are composed of about 71% hydrogen and 27% helium,[99] as measured by mass, with a small fraction of heavier elements. Typically the portion of heavy elements is measured in terms of the iron content of the stellar atmosphere, as iron is a common element and its absorption lines are relatively easy to measure. The portion of heavier elements may be an indicator of the likelihood that the star has a planetary system.[100]
The star with the lowest iron content ever measured is the dwarf HE1327-2326, with only 1/200,000th the iron content of the Sun.[101] By contrast, the super-metal-rich star μ Leonis has nearly double the abundance of iron as the Sun, while the planet-bearing star 14 Herculis has nearly triple the iron.[102] There also exist chemically peculiar stars that show unusual abundances of certain elements in their spectrum; especially chromium and rare earth elements.[103] Stars with cooler outer atmospheres, including the Sun, can form various diatomic and polyatomic molecules.[104]
Diameter
Main articles: List of largest stars, List of least voluminous stars, and Solar radius
Stars vary widely in size. In each image in the sequence, the right-most object appears as the left-most object in the next panel. The Earth appears at right in panel 1 and the Sun is second from the right in panel 3. The rightmost star at panel 6 is UY Scuti, the largest known star.
Due to their great distance from the Earth, all stars except the Sun appear to the unaided eye as shining points in the night sky that twinkle because of the effect of the Earth's atmosphere. The Sun is also a star, but it is close enough to the Earth to appear as a disk instead, and to provide daylight. Other than the Sun, the star with the largest apparent size is R Doradus, with an angular diameter of only 0.057 arcseconds.[105]
The disks of most stars are much too small in angular size to be observed with current ground-based optical telescopes, and so interferometer telescopes are required to produce images of these objects. Another technique for measuring the angular size of stars is through occultation. By precisely measuring the drop in brightness of a star as it is occulted by the Moon (or the rise in brightness when it reappears), the star's angular diameter can be computed.[106]
Stars range in size from neutron stars, which vary anywhere from 20 to 40 km (25 mi) in diameter, to supergiants like Betelgeuse in the Orion constellation, which has a diameter 7002887000000000000♠887±203[107] to 950[108] times that of our sun. Betelgeuse, however, has a much lower density than the Sun.[109]
Kinematics
Main article: Stellar kinematics
The Pleiades, an open cluster of stars in the constellation of Taurus. These stars share a common motion through space.[110]
The motion of a star relative to the Sun can provide useful information about the origin and age of a star, as well as the structure and evolution of the surrounding galaxy. The components of motion of a star consist of the radial velocity toward or away from the Sun, and the traverse angular movement, which is called its proper motion.
Radial velocity is measured by the doppler shift of the star's spectral lines, and is given in units of km/s. The proper motion of a star, its parallax, is determined by precise astrometric measurements in units of milli-arc seconds (mas) per year. With knowledge of the star's parallax and its distance, the proper motion velocity can be calculated. Together with the radial velocity, the total velocity can be calculated. Stars with high rates of proper motion are likely to be relatively close to the Sun, making them good candidates for parallax measurements.[111]
When both rates of movement are known, the space velocity of the star relative to the Sun or the galaxy can be computed. Among nearby stars, it has been found that younger population I stars have generally lower velocities than older, population II stars. The latter have elliptical orbits that are inclined to the plane of the galaxy.[112] A comparison of the kinematics of nearby stars has allowed astronomers to trace their origin to common points in giant molecular clouds, and are referred to as stellar associations.[113]
Magnetic field
Main article: Stellar magnetic field
Surface magnetic field of SU Aur (a young star of T Tauri type), reconstructed by means of Zeeman–Doppler imaging
The magnetic field of a star is generated within regions of the interior where convective circulation occurs. This movement of conductive plasma functions like a dynamo, wherein the movement of electrical charges induce magnetic fields, as does a mechanical dynamo. Those magnetic fields have a great range that extend throughout and beyond the star. The strength of the magnetic field varies with the mass and composition of the star, and the amount of magnetic surface activity depends upon the star's rate of rotation. This surface activity produces starspots, which are regions of strong magnetic fields and lower than normal surface temperatures. Coronal loops are arching magnetic field flux lines that rise from a star's surface into the star's outer atmosphere, its corona. The coronal loops can be seen due to the plasma they conduct along their length. Stellar flares are bursts of high-energy particles that are emitted due to the same magnetic activity.[114]
Young, rapidly rotating stars tend to have high levels of surface activity because of their magnetic field. The magnetic field can act upon a star's stellar wind, functioning as a brake to gradually slow the rate of rotation with time. Thus, older stars such as the Sun have a much slower rate of rotation and a lower level of surface activity. The activity levels of slowly rotating stars tend to vary in a cyclical manner and can shut down altogether for periods of time.[115] During the Maunder Minimum, for example, the Sun underwent a 70-year period with almost no sunspot activity.
Mass
Main article: Stellar mass
One of the most massive stars known is Eta Carinae,[116] which, with 100–150 times as much mass as the Sun, will have a lifespan of only several million years. Studies of the most massive open clusters suggests 150 M☉ as an upper limit for stars in the current era of the universe.[117] This represents an empirical value for the theoretical limit on the mass of forming stars due to increasing radiation pressure on the accreting gas cloud. Several stars in the R136 cluster in the Large Magellanic Cloud have been measured with larger masses,[118] but it has been determined that they could have been created through the collision and merger of massive stars in close binary systems, sidestepping the 150 M☉ limit on massive star formation.[119]
The reflection nebula NGC 1999 is brilliantly illuminated by V380 Orionis (center), a variable star with about 3.5 times the mass of the Sun. The black patch of sky is a vast hole of empty space and not a dark nebula as previously thought.
The first stars to form after the Big Bang may have been larger, up to 300 M☉,[120] due to the complete absence of elements heavier than lithium in their composition. This generation of supermassive population III stars is likely to have existed in the very early universe (i.e., they are observed to have a high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life. In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60.[121][122]
With a mass only 80 times that of Jupiter (MJ), 2MASS J0523-1403 is the smallest known star undergoing nuclear fusion in its core.[123] For stars with metallicity similar to the Sun, the theoretical minimum mass the star can have and still undergo fusion at the core, is estimated to be about 75 MJ.[124][125] When the metallicity is very low, however, the minimum star size seems to be about 8.3% of the solar mass, or about 87 MJ.[125][126] Smaller bodies called brown dwarfs, occupy a poorly defined grey area between stars and gas giants.
The combination of the radius and the mass of a star determines its surface gravity. Giant stars have a much lower surface gravity than do main sequence stars, while the opposite is the case for degenerate, compact stars such as white dwarfs. The surface gravity can influence the appearance of a star's spectrum, with higher gravity causing a broadening of the absorption lines.[33]
Rotation
Main article: Stellar rotation
The rotation rate of stars can be determined through spectroscopic measurement, or more exactly determined by tracking their starspots. Young stars can have a rotation greater than 100 km/s at the equator. The B-class star Achernar, for example, has an equatorial velocity of about 225 km/s or greater, causing its equator to bulge outward and giving it an equatorial diameter that is more than 50% greater than between the poles. This rate of rotation is just below the critical velocity of 300 km/s at which speed the star would break apart.[127] By contrast, the Sun rotates once every 25 – 35 days, with an equatorial velocity of 1.994 km/s.[citation needed] A main sequence star's magnetic field and the stellar wind serve to slow its rotation by a significant amount as it evolves on the main sequence.[128]
Degenerate stars have contracted into a compact mass, resulting in a rapid rate of rotation. However they have relatively low rates of rotation compared to what would be expected by conservation of angular momentum—the tendency of a rotating body to compensate for a contraction in size by increasing its rate of spin. A large portion of the star's angular momentum is dissipated as a result of mass loss through the stellar wind.[129] In spite of this, the rate of rotation for a pulsar can be very rapid. The pulsar at the heart of the Crab nebula, for example, rotates 30 times per second.[130] The rotation rate of the pulsar will gradually slow due to the emission of radiation.[citation needed]
Temperature
The surface temperature of a main sequence star is determined by the rate of energy production of its core and by its radius, and is often estimated from the star's color index.[131] The temperature is normally given in terms of an effective temperature, which is the temperature of an idealized black body that radiates its energy at the same luminosity per surface area as the star. Note that the effective temperature is only a representative of the surface, as the temperature increases toward the core.[132] The temperature in the core region of a star is several million kelvins.[133]
The stellar temperature will determine the rate of ionization of various elements, resulting in characteristic absorption lines in the spectrum. The surface temperature of a star, along with its visual absolute magnitude and absorption features, is used to classify a star (see classification below).[33]
Massive main sequence stars can have surface temperatures of 50,000 K. Smaller stars such as the Sun have surface temperatures of a few thousand K. Red giants have relatively low surface temperatures of about 3,600 K; but they also have a high luminosity due to their large exterior surface area.[134]
Radiation
The energy produced by stars, a product of nuclear fusion, radiates to space as both electromagnetic radiation and particle radiation. The particle radiation emitted by a star is manifested as the stellar wind,[135] which streams from the outer layers as electrically charged protons and alpha and beta particles. Although almost massless, there also exists a steady stream of neutrinos emanating from the star's core.
The production of energy at the core is the reason stars shine so brightly: every time two or more atomic nuclei fuse together to form a single atomic nucleus of a new heavier element, gamma ray photons are released from the nuclear fusion product. This energy is converted to other forms of electromagnetic energy of lower frequency, such as visible light, by the time it reaches the star's outer layers.
The color of a star, as determined by the most intense frequency of the visible light, depends on the temperature of the star's outer layers, including its photosphere.[136] Besides visible light, stars also emit forms of electromagnetic radiation that are invisible to the human eye. In fact, stellar electromagnetic radiation spans the entire electromagnetic spectrum, from the longest wavelengths of radio waves through infrared, visible light, ultraviolet, to the shortest of X-rays, and gamma rays. From the standpoint of total energy emitted by a star, not all components of stellar electromagnetic radiation are significant, but all frequencies provide insight into the star's physics.
Using the stellar spectrum, astronomers can also determine the surface temperature, surface gravity, metallicity and rotational velocity of a star. If the distance of the star is found, such as by measuring the parallax, then the luminosity of the star can be derived. The mass, radius, surface gravity, and rotation period can then be estimated based on stellar models. (Mass can be calculated for stars in binary systems by measuring their orbital velocities and distances. Gravitational microlensing has been used to measure the mass of a single star.[137]) With these parameters, astronomers can also estimate the age of the star.[138]
Luminosity
The luminosity of a star is the amount of light and other forms of radiant energy it radiates per unit of time. It has units of power. The luminosity of a star is determined by its radius and surface temperature. Many stars do not radiate uniformly across their entire surface. The rapidly rotating star Vega, for example, has a higher energy flux (power per unit area) at its poles than along its equator.[139]
Patches of the star's surface with a lower temperature and luminosity than average are known as starspots. Small, dwarf stars such as our Sun generally have essentially featureless disks with only small starspots. Giant stars have much larger, more obvious starspots,[140] and they also exhibit strong stellar limb darkening. That is, the brightness decreases towards the edge of the stellar disk.[141] Red dwarf flare stars such as UV Ceti may also possess prominent starspot features.[142]
Magnitude
Main articles: Apparent magnitude and Absolute magnitude
The apparent brightness of a star is expressed in terms of its apparent magnitude. It is a function of the star's luminosity, its distance from Earth, the extinction effect of interstellar dust and gas, and the altering of the star's light as it passes through Earth's atmosphere. Intrinsic or absolute magnitude is directly related to a star's luminosity, and is what the apparent magnitude a star would be if the distance between the Earth and the star were 10 parsecs (32.6 light-years).
Number of stars brighter than magnitude
Apparent
magnitude
Number
of stars[143]
0 4
1 15
2 48
3 171
4 513
5 1,602
6 4,800
7 14,000
Both the apparent and absolute magnitude scales are logarithmic units: one whole number difference in magnitude is equal to a brightness variation of about 2.5 times[144] (the 5th root of 100 or approximately 2.512). This means that a first magnitude star (+1.00) is about 2.5 times brighter than a second magnitude (+2.00) star, and about 100 times brighter than a sixth magnitude star (+6.00). The faintest stars visible to the naked eye under good seeing conditions are about magnitude +6.
On both apparent and absolute magnitude scales, the smaller the magnitude number, the brighter the star; the larger the magnitude number, the fainter the star. The brightest stars, on either scale, have negative magnitude numbers. The variation in brightness (ΔL) between two stars is calculated by subtracting the magnitude number of the brighter star (mb) from the magnitude number of the fainter star (mf), then using the difference as an exponent for the base number 2.512; that is to say:
Δ m = m f − m b {\displaystyle \Delta {m}=m_{\mathrm {f} }-m_{\mathrm {b} }}
2.512 Δ m = Δ L {\displaystyle 2.512^{\Delta {m}}=\Delta {L}}
Relative to both luminosity and distance from Earth, a star's absolute magnitude (M) and apparent magnitude (m) are not equivalent;[144] for example, the bright star Sirius has an apparent magnitude of −1.44, but it has an absolute magnitude of +1.41.
The Sun has an apparent magnitude of −26.7, but its absolute magnitude is only +4.83. Sirius, the brightest star in the night sky as seen from Earth, is approximately 23 times more luminous than the Sun, while Canopus, the second brightest star in the night sky with an absolute magnitude of −5.53, is approximately 14,000 times more luminous than the Sun. Despite Canopus being vastly more luminous than Sirius, however, Sirius appears brighter than Canopus. This is because Sirius is merely 8.6 light-years from the Earth, while Canopus is much farther away at a distance of 310 light-years.
As of 2006, the star with the highest known absolute magnitude is LBV 1806-20, with a magnitude of −14.2. This star is at least 5,000,000 times more luminous than the Sun.[145] The least luminous stars that are currently known are located in the NGC 6397 cluster. The faintest red dwarfs in the cluster were magnitude 26, while a 28th magnitude white dwarf was also discovered. These faint stars are so dim that their light is as bright as a birthday candle on the Moon when viewed from the Earth.[146]
Classification
Surface temperature ranges for
different stellar classes[147]
Class
Temperature
Sample star
O 33,000 K or more Zeta Ophiuchi
B 10,500–30,000 K Rigel
A 7,500–10,000 K Altair
F 6,000–7,200 K Procyon A
G 5,500–6,000 K Sun
K 4,000–5,250 K Epsilon Indi
M 2,600–3,850 K Proxima Centauri
Main article: Stellar classification
The current stellar classification system originated in the early 20th century, when stars were classified from A to Q based on the strength of the hydrogen line.[148] It was thought that the hydrogen line strength was a simple linear function of temperature. Instead, it was more complicated: it strengthened with increasing temperature, peaked near 9000 K, and then declined at greater temperatures. The classifications were since reordered by temperature, on which the modern scheme is based.[149]
Stars are given a single-letter classification according to their spectra, ranging from type O, which are very hot, to M, which are so cool that molecules may form in their atmospheres. The main classifications in order of decreasing surface temperature are: O, B, A, F, G, K, and M. A variety of rare spectral types are given special classifications. The most common of these are types L and T, which classify the coldest low-mass stars and brown dwarfs. Each letter has 10 sub-divisions, numbered from 0 to 9, in order of decreasing temperature. However, this system breaks down at extreme high temperatures as classes O0 and O1 may not exist.[150]
In addition, stars may be classified by the luminosity effects found in their spectral lines, which correspond to their spatial size and is determined by their surface gravity. These range from 0 (hypergiants) through III (giants) to V (main sequence dwarfs); some authors add VII (white dwarfs). Main sequence stars fall along a narrow, diagonal band when graphed according to their absolute magnitude and spectral type.[150] The Sun is a main sequence G2V yellow dwarf of intermediate temperature and ordinary size.
Additional nomenclature, in the form of lower-case letters added to the end of the spectral type to indicate peculiar features of the spectrum. For example, an "e" can indicate the presence of emission lines; "m" represents unusually strong levels of metals, and "var" can mean variations in the spectral type.[150]
White dwarf stars have their own class that begins with the letter D. This is further sub-divided into the classes DA, DB, DC, DO, DZ, and DQ, depending on the types of prominent lines found in the spectrum. This is followed by a numerical value that indicates the temperature.[151]
Variable stars
Main article: Variable star
The asymmetrical appearance of Mira, an oscillating variable star.
Variable stars have periodic or random changes in luminosity because of intrinsic or extrinsic properties. Of the intrinsically variable stars, the primary types can be subdivided into three principal groups.
During their stellar evolution, some stars pass through phases where they can become pulsating variables. Pulsating variable stars vary in radius and luminosity over time, expanding and contracting with periods ranging from minutes to years, depending on the size of the star. This category includes Cepheid and Cepheid-like stars, and long-period variables such as Mira.[152]
Eruptive variables are stars that experience sudden increases in luminosity because of flares or mass ejection events.[152] This group includes protostars, Wolf-Rayet stars, and flare stars, as well as giant and supergiant stars.
Cataclysmic or explosive variable stars are those that undergo a dramatic change in their properties. This group includes novae and supernovae. A binary star system that includes a nearby white dwarf can produce certain types of these spectacular stellar explosions, including the nova and a Type 1a supernova.[4] The explosion is created when the white dwarf accretes hydrogen from the companion star, building up mass until the hydrogen undergoes fusion.[153] Some novae are also recurrent, having periodic outbursts of moderate amplitude.[152]
Stars can also vary in luminosity because of extrinsic factors, such as eclipsing binaries, as well as rotating stars that produce extreme starspots.[152] A notable example of an eclipsing binary is Algol, which regularly varies in magnitude from 2.3 to 3.5 over a period of 2.87 days.[citation needed]
Structure
Main article: Stellar structure
Internal structures of main sequence stars, convection zones with arrowed cycles and radiative zones with red flashes. To the left a low-mass red dwarf, in the center a mid-sized yellow dwarf, and, at the right, a massive blue-white main sequence star.
The interior of a stable star is in a state of hydrostatic equilibrium: the forces on any small volume almost exactly counterbalance each other. The balanced forces are inward gravitational force and an outward force due to the pressure gradient within the star. The pressure gradient is established by the temperature gradient of the plasma; the outer part of the star is cooler than the core. The temperature at the core of a main sequence or giant star is at least on the order of 107 K. The resulting temperature and pressure at the hydrogen-burning core of a main sequence star are sufficient for nuclear fusion to occur and for sufficient energy to be produced to prevent further collapse of the star.[154][155]
As atomic nuclei are fused in the core, they emit energy in the form of gamma rays. These photons interact with the surrounding plasma, adding to the thermal energy at the core. Stars on the main sequence convert hydrogen into helium, creating a slowly but steadily increasing proportion of helium in the core. Eventually the helium content becomes predominant, and energy production ceases at the core. Instead, for stars of more than 0.4 M☉, fusion occurs in a slowly expanding shell around the degenerate helium core.[156]
In addition to hydrostatic equilibrium, the interior of a stable star will also maintain an energy balance of thermal equilibrium. There is a radial temperature gradient throughout the interior that results in a flux of energy flowing toward the exterior. The outgoing flux of energy leaving any layer within the star will exactly match the incoming flux from below.
The radiation zone is the region of the stellar interior where the flux of energy outward is dependent on radiative heat transfer, since convective heat transfer is inefficient in that zone. In this region the plasma will not be perturbed, and any mass motions will die out. If this is not the case, however, then the plasma becomes unstable and convection will occur, forming a convection zone. This can occur, for example, in regions where very high energy fluxes occur, such as near the core or in areas with high opacity (making radiatative heat transfer inefficient) as in the outer envelope.[155]
The occurrence of convection in the outer envelope of a main sequence star depends on the star's mass. Stars with several times the mass of the Sun have a convection zone deep within the interior and a radiative zone in the outer layers. Smaller stars such as the Sun are just the opposite, with the convective zone located in the outer layers.[157] Red dwarf stars with less than 0.4 M☉ are convective throughout, which prevents the accumulation of a helium core.[2] For most stars the convective zones will also vary over time as the star ages and the constitution of the interior is modified.[155]
This diagram shows a cross-section of the Sun.
The photosphere is that portion of a star that is visible to an observer. This is the layer at which the plasma of the star becomes transparent to photons of light. From here, the energy generated at the core becomes free to propagate into space. It is within the photosphere that sun spots, regions of lower than average temperature, appear.
Above the level of the photosphere is the stellar atmosphere. In a main sequence star such as the Sun, the lowest level of the atmosphere, just above the photosphere, is the thin chromosphere region, where spicules appear and stellar flares begin. Above this is the transition region, where the temperature rapidly increases within a distance of only 100 km (62 mi). Beyond this is the corona, a volume of super-heated plasma that can extend outward to several million kilometres.[158] The existence of a corona appears to be dependent on a convective zone in the outer layers of the star.[157] Despite its high temperature, and the corona emits very little light, due to its low gas density. The corona region of the Sun is normally only visible during a solar eclipse.
From the corona, a stellar wind of plasma particles expands outward from the star, until it interacts with the interstellar medium. For the Sun, the influence of its solar wind extends throughout a bubble-shaped region called the heliosphere.[159]
Nuclear fusion reaction pathways
Main article: Stellar nucleosynthesis
Overview of the proton-proton chain
The carbon-nitrogen-oxygen cycle
A variety of nuclear fusion reactions take place in the cores of stars, that depend upon their mass and composition. When nuclei fuse, the mass of the fused product is less than the mass of the original parts. This lost mass is converted to electromagnetic energy, according to the mass–energy equivalence relationship E = mc2.[1]
The hydrogen fusion process is temperature-sensitive, so a moderate increase in the core temperature will result in a significant increase in the fusion rate. As a result, the core temperature of main sequence stars only varies from 4 million kelvin for a small M-class star to 40 million kelvin for a massive O-class star.[133]
In the Sun, with a 10-million-kelvin core, hydrogen fuses to form helium in the proton–proton chain reaction:[160]
41H → 22H + 2e+ + 2νe(2 x 0.4 MeV)
2e+ + 2e− → 2γ (2 x 1.0 MeV)
21H + 22H → 23He + 2γ (2 x 5.5 MeV)
23He → 4He + 21H (12.9 MeV)
These reactions result in the overall reaction:
41H → 4He + 2e+ + 2γ + 2νe (26.7 MeV)
where e+ is a positron, γ is a gamma ray photon, νe is a neutrino, and H and He are isotopes of hydrogen and helium, respectively. The energy released by this reaction is in millions of electron volts, which is actually only a tiny amount of energy. However enormous numbers of these reactions occur constantly, producing all the energy necessary to sustain the star's radiation output. In comparison, the combustion of two hydrogen gas molecules with one oxygen gas molecule releases only 5.7 eV.
Minimum stellar mass required for fusion
Element
Solar
masses
Hydrogen 0.01
Helium 0.4
Carbon 5[161]
Neon 8
In more massive stars, helium is produced in a cycle of reactions catalyzed by carbon called the carbon-nitrogen-oxygen cycle.[160]
In evolved stars with cores at 100 million kelvin and masses between 0.5 and 10 M☉, helium can be transformed into carbon in the triple-alpha process that uses the intermediate element beryllium:[160]
4He + 4He + 92 keV → 8*Be
4He + 8*Be + 67 keV → 12*C
12*C → 12C + γ + 7.4 MeV
For an overall reaction of:
34He → 12C + γ + 7.2 MeV
In massive stars, heavier elements can also be burned in a contracting core through the neon-burning process and oxygen-burning process. The final stage in the stellar nucleosynthesis process is the silicon-burning process that results in the production of the stable isotope iron-56, an endothermic process that consumes energy, and so further energy can only be produced through gravitational collapse.[160]
The example below shows the amount of time required for a star of 20 M☉ to consume all of its nuclear fuel. As an O-class main sequence star, it would be 8 times the solar radius and 62,000 times the Sun's luminosity.[162]
Fuel
material
Temperature
(million kelvins)
Density
(kg/cm3)
Burn duration
(τ in years)
H 37 0.0045 8.1 million
He 188 0.97 1.2 million
C 870 170 976
Ne 1,570 3,100 0.6
O 1,980 5,550 1.25
S/Si 3,340 33,400 0.0315[163]
See also
Star portal
Astronomy portal
Exoplanet host stars
Lists of stars
List of largest known stars
Outline of astronomy
Sidereal time
Star clocks
Star count
Stars and planetary systems in fiction
Stellar astronomy
Stellar dynamics
Twinkle, Twinkle, Little Star (children's nursery rhyme)
References
^ Jump up to: a b Bahcall, John N. (June 29, 2000). "How the Sun Shines". Nobel Foundation. Retrieved 2006-08-30.
^ Jump up to: a b c Richmond, Michael. "Late stages of evolution for low-mass stars". Rochester Institute of Technology. Retrieved 2006-08-04.
Jump up ^ "Stellar Evolution & Death". NASA Observatorium. Archived from the original on 2008-02-10. Retrieved 2006-06-08.
^ Jump up to: a b c Iben, Icko Jr. (1991). "Single and binary star evolution". Astrophysical Journal Supplement Series. 76: 55–114. Bibcode:1991ApJS...76...55I. doi:10.1086/191565.
^ Jump up to: a b Forbes, George (1909). History of Astronomy. London: Watts & Co. ISBN 1-153-62774-4.
Jump up ^ Hevelius, Johannis (1690). Firmamentum Sobiescianum, sive Uranographia. Gdansk.
Jump up ^ Tøndering, Claus. "Other ancient calendars". WebExhibits. Retrieved 2006-12-10.
Jump up ^ von Spaeth, Ove (2000). "Dating the Oldest Egyptian Star Map". Centaurus International Magazine of the History of Mathematics, Science and Technology. 42 (3): 159–179. Bibcode:2000Cent...42..159V. doi:10.1034/j.1600-0498.2000.420301.x. Retrieved 2007-10-21.
Jump up ^ North, John (1995). The Norton History of Astronomy and Cosmology. New York and London: W.W. Norton & Company. pp. 30–31. ISBN 0-393-03656-1.
Jump up ^ Murdin, P. (November 2000). "Aristillus (c. 200 BC)". Encyclopedia of Astronomy and Astrophysics. Bibcode:2000eaa..bookE3440.. doi:10.1888/0333750888/3440. ISBN 0-333-75088-8.
Jump up ^ Grasshoff, Gerd (1990). The history of Ptolemy's star catalogue. Springer. pp. 1–5. ISBN 0-387-97181-5.
Jump up ^ Pinotsis, Antonios D. "Astronomy in Ancient Rhodes". Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Athens. Retrieved 2009-06-02.
Jump up ^ Clark, D. H.; Stephenson, F. R. (June 29, 1981). "The Historical Supernovae". Supernovae: A survey of current research; Proceedings of the Advanced Study Institute. Cambridge, England: Dordrecht, D. Reidel Publishing Co. pp. 355–370. Bibcode:1982ASIC...90..355C.
Jump up ^ Zhao, Fu-Yuan; Strom, R. G.; Jiang, Shi-Yang (2006). "The Guest Star of AD185 Must Have Been a Supernova". Chinese Journal of Astronomy and Astrophysics. 6 (5): 635–640. Bibcode:2006ChJAA...6..635Z. doi:10.1088/1009-9271/6/5/17.
Jump up ^ "Astronomers Peg Brightness of History's Brightest Star". NAOA News. March 5, 2003. Retrieved 2006-06-08.
Jump up ^ Frommert, Hartmut; Kronberg, Christine (August 30, 2006). "Supernova 1054 – Creation of the Crab Nebula". SEDS. University of Arizona.
Jump up ^ Duyvendak, J. J. L. (April 1942). "Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part I. The Ancient Oriental Chronicles". Publications of the Astronomical Society of the Pacific. 54 (318): 91–94. Bibcode:1942PASP...54...91D. doi:10.1086/125409.
Mayall, N. U.; Oort, Jan Hendrik (April 1942). "Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part II. The Astronomical Aspects". Publications of the Astronomical Society of the Pacific. 54 (318): 95–104. Bibcode:1942PASP...54...95M. doi:10.1086/125410.
Jump up ^ Brecher, K.; et al. (1983). "Ancient records and the Crab Nebula supernova". The Observatory. 103: 106–113. Bibcode:1983Obs...103..106B.
Jump up ^ Kennedy, Edward S. (1962). "Review: The Observatory in Islam and Its Place in the General History of the Observatory by Aydin Sayili". Isis. 53 (2): 237–239. doi:10.1086/349558.
Jump up ^ Jones, Kenneth Glyn (1991). Messier's nebulae and star clusters. Cambridge University Press. p. 1. ISBN 0-521-37079-5.
Jump up ^ Zahoor, A. (1997). "Al-Biruni". Hasanuddin University. Archived from the original on 2008-06-26. Retrieved 2007-10-21.
Jump up ^ Montada, Josep Puig (September 28, 2007). "Ibn Bajja". Stanford Encyclopedia of Philosophy. Retrieved 2008-07-11.
^ Jump up to: a b c Drake, Stephen A. (August 17, 2006). "A Brief History of High-Energy (X-ray & Gamma-Ray) Astronomy". NASA HEASARC. Retrieved 2006-08-24.
Jump up ^ Greskovic, Peter; Rudy, Peter (July 24, 2006). "Exoplanets". ESO. Retrieved 2012-06-15.
Jump up ^ Ahmad, I. A. (1995). "The impact of the Qur'anic conception of astronomical phenomena on Islamic civilization". Vistas in Astronomy. 39 (4): 395–403 [402]. Bibcode:1995VA.....39..395A. doi:10.1016/0083-6656(95)00033-X.
Jump up ^ Setia, Adi (2004). "Fakhr Al-Din Al-Razi on Physics and the Nature of the Physical World: A Preliminary Survey" (PDF). Islam & Science. 2 (2).
Jump up ^ Hoskin, Michael (1998). "The Value of Archives in Writing the History of Astronomy". Space Telescope Science Institute. Retrieved 2006-08-24.
Jump up ^ Proctor, Richard A. (1870). "Are any of the nebulæ star-systems?". Nature. 1 (13): 331–333. Bibcode:1870Natur...1..331P. doi:10.1038/001331a0.
Jump up ^ MacDonnell, Joseph. "Angelo Secchi, S.J. (1818–1878) the Father of Astrophysics". Fairfield University. Archived from the original on 2011-07-21. Retrieved 2006-10-02.
Jump up ^ Aitken, Robert G. (1964). The Binary Stars. New York: Dover Publications Inc. p. 66. ISBN 0-486-61102-7.
Jump up ^ Michelson, A. A.; Pease, F. G. (1921). "Measurement of the diameter of Alpha Orionis with the interferometer". Astrophysical Journal. 53: 249–259. Bibcode:1921ApJ....53..249M. doi:10.1086/142603.
Jump up ^ "" Payne-Gaposchkin, Cecilia Helena." CWP". University of California. Archived from the original on 2005-03-18. Retrieved 2013-02-21.
^ Jump up to: a b c Unsöld, Albrecht (2001). The New Cosmos (5th ed.). New York: Springer. pp. 180–185, 215–216. ISBN 3-540-67877-8.
Jump up ^ e. g. Battinelli, Paolo; Demers, Serge; Letarte, Bruno (2003). "Carbon Star Survey in the Local Group. V. The Outer Disk of M31". The Astronomical Journal. 125 (3): 1298–1308. Bibcode:2003AJ....125.1298B. doi:10.1086/346274.
Jump up ^ "Millennium Star Atlas marks the completion of ESA's Hipparcos Mission". ESA. December 8, 1997. Retrieved 2007-08-05.
Jump up ^ Villard, Ray; Freedman, Wendy L. (October 26, 1994). "Hubble Space Telescope Measures Precise Distance to the Most Remote Galaxy Yet". Hubble Site. Retrieved 2007-08-05.
Jump up ^ "Hubble Completes Eight-Year Effort to Measure Expanding Universe". Hubble Site. May 25, 1999. Retrieved 2007-08-02.
Jump up ^ "UBC Prof., alumnus discover most distant star clusters: a billion light-years away". UBC Public Affairs. January 8, 2007. Retrieved 2015-06-28.
Jump up ^ Gibney, Elizabeth (28 February 2018). "Astronomers detect light from the Universe's first stars - Surprises in signal from cosmic dawn also hint at presence of dark matter". Nature. Retrieved 28 February 2018.
Jump up ^ Kelly, Patrick L.; et al. (2 April 2018). "Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens". Nature. 2 (4): 334–342. arXiv:1706.10279  . Bibcode:2018NatAs...2..334K. doi:10.1038/s41550-018-0430-3. Retrieved 2 April 2018. CS1 maint: Explicit use of et al. (link)
Jump up ^ Howell, Elizabeth (2 April 2018). "Rare Cosmic Alignment Reveals Most Distant Star Ever Seen". Space.com. Retrieved 2 April 2018.
Jump up ^ "The onset of star formation 250 million years after Big Bang" (PDF). Nature. 20: 75–83. May 2018.
Jump up ^ Koch-Westenholz, Ulla; Koch, Ulla Susanne (1995). Mesopotamian astrology: an introduction to Babylonian and Assyrian celestial divination. Carsten Niebuhr Institute Publications. 19. Museum Tusculanum Press. p. 163. ISBN 87-7289-287-0.
^ Jump up to: a b Coleman, Leslie S. "Myths, Legends and Lore". Frosty Drew Observatory. Retrieved 2012-06-15.
Jump up ^ "Naming Astronomical Objects". International Astronomical Union (IAU). Retrieved 2009-01-30.
Jump up ^ "Naming Stars". Students for the Exploration and Development of Space (SEDS). Retrieved 2009-01-30.
Jump up ^ Lyall, Francis; Larsen, Paul B. (2009). "Chapter 7: The Moon and Other Celestial Bodies". Space Law: A Treatise. Ashgate Publishing, Ltd. p. 176. ISBN 0-7546-4390-5.
Jump up ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
Jump up ^ "Star naming". Scientia Astrophysical Organization. 2005. Archived from the original on 2010-06-17. Retrieved 2010-06-29.
Jump up ^ "Disclaimer: Name a star, name a rose and other, similar enterprises". British Library. The British Library Board. Archived from the original on 2010-01-19. Retrieved 2010-06-29.
Jump up ^ Andersen, Johannes. "Buying Stars and Star Names". International Astronomical Union. Retrieved 2010-06-24.
Jump up ^ Pliat, Phil (September–October 2006). "Name Dropping: Want to Be a Star?". Skeptical Inquirer. 30.5. Retrieved 2010-06-29.
Jump up ^ Adams, Cecil (April 1, 1998). "Can you pay $35 to get a star named after you?". The Straight Dope. Retrieved 2006-08-13.
Jump up ^ Golden, Frederick; Faflick, Philip (January 11, 1982). "Science: Stellar Idea or Cosmic Scam?". Times Magazine. Time Inc. Retrieved 2010-06-24.
Jump up ^ Di Justo, Patrick (December 26, 2001). "Buy a Star, But It's Not Yours". Wired. Condé Nast Digital. Retrieved 2010-06-29.
Jump up ^ Plait, Philip C. (2002). Bad astronomy: misconceptions and misuses revealed, from astrology to the moon landing "hoax". John Wiley and Sons. pp. 237–240. ISBN 0-471-40976-6.
Jump up ^ Sclafani, Tom (May 8, 1998). "Consumer Affairs Commissioner Polonetsky Warns Consumers: "Buying A Star Won't Make You One"". National Astronomy and Ionosphere Center, Aricebo Observatory. Archived from the original on January 11, 2006. Retrieved 2010-06-24.
^ Jump up to: a b c d Prsa, A.; Harmanec, P.; Torres, G.; Mamajek, E.; et al. (2016). "Nominal values for selected solar and planetary quantities: IAU 2015 Resolution B3". Astronomical Journal. 152 (2): 41. arXiv:1605.09788  . Bibcode:2016AJ....152...41P. doi:10.3847/0004-6256/152/2/41.
Jump up ^ Woodward, P. R. (1978). "Theoretical models of star formation". Annual Review of Astronomy and Astrophysics. 16 (1): 555–584. Bibcode:1978ARA&A..16..555W. doi:10.1146/annurev.aa.16.090178.003011.
Jump up ^ Lada, C. J.; Lada, E. A. (2003). "Embedded Clusters in Molecular Clouds". Annual Review of Astronomy and Astrophysics. 41 (1): 57–115. arXiv:astro-ph/0301540  . Bibcode:2003ARA&A..41...57L. doi:10.1146/annurev.astro.41.011802.094844.
Jump up ^ Kwok, Sun (2000). The origin and evolution of planetary nebulae. Cambridge astrophysics series. 33. Cambridge University Press. pp. 103–104. ISBN 0-521-62313-8.
^ Jump up to: a b Adams, Fred C.; Laughlin, Gregory; Graves, Genevieve J. M. "Red Dwarfs and the End of the Main Sequence" (PDF). Gravitational Collapse: From Massive Stars to Planets. Revista Mexicana de Astronomía y Astrofísica. pp. 46–49. Bibcode:2004RMxAC..22...46A. Retrieved 2008-06-24.
Jump up ^ Elmegreen, B. G.; Lada, C. J. (1977). "Sequential formation of subgroups in OB associations". Astrophysical Journal, Part 1. 214: 725–741. Bibcode:1977ApJ...214..725E. doi:10.1086/155302.
Jump up ^ Getman, K. V.; et al. (2012). "The Elephant Trunk Nebula and the Trumpler 37 cluster: contribution of triggered star formation to the total population of an H II region". Monthly Notices of the Royal Astronomical Society. 426 (4): 2917–2943. arXiv:1208.1471  . Bibcode:2012MNRAS.426.2917G. doi:10.1111/j.1365-2966.2012.21879.x.
Jump up ^ Smith, Michael David (2004). The Origin of Stars. Imperial College Press. pp. 57–68. ISBN 1-86094-501-5.
Jump up ^ Seligman, Courtney. "Slow Contraction of Protostellar Cloud". Self-published. Archived from the original on 2008-06-23. Retrieved 2006-09-05.
Jump up ^ Bally, J.; Morse, J.; Reipurth, B. (1996). "The Birth of Stars: Herbig-Haro Jets, Accretion and Proto-Planetary Disks". In Benvenuti, Piero; Macchetto, F. D.; Schreier, Ethan J. Science with the Hubble Space Telescope – II. Proceedings of a workshop held in Paris, France, December 4–8, 1995. Space Telescope Science Institute. p. 491. Bibcode:1996swhs.conf..491B.
Jump up ^ Smith, Michael David (2004). The origin of stars. Imperial College Press. p. 176. ISBN 1-86094-501-5.
Jump up ^ Megeath, Tom (May 11, 2010). "Herschel finds a hole in space". ESA. Retrieved 2010-05-17.
Jump up ^ Duquennoy, A.; Mayor, M. (1991). "Multiplicity among solar-type stars in the solar neighbourhood. II – Distribution of the orbital elements in an unbiased sample". Astronomy & Astrophysics. 248 (2): 485–524. Bibcode:1991A&A...248..485D.
Jump up ^ Mengel, J. G.; et al. (1979). "Stellar evolution from the zero-age main sequence". Astrophysical Journal Supplement Series. 40: 733–791. Bibcode:1979ApJS...40..733M. doi:10.1086/190603.
^ Jump up to: a b Sackmann, I. J.; Boothroyd, A. I.; Kraemer, K. E. (1993). "Our Sun. III. Present and Future". Astrophysical Journal. 418: 457. Bibcode:1993ApJ...418..457S. doi:10.1086/173407.
Jump up ^ Wood, B. E.; et al. (2002). "Measured Mass-Loss Rates of Solar-like Stars as a Function of Age and Activity". The Astrophysical Journal. 574 (1): 412–425. arXiv:astro-ph/0203437  . Bibcode:2002ApJ...574..412W. doi:10.1086/340797.
Jump up ^ de Loore, C.; de Greve, J. P.; Lamers, H. J. G. L. M. (1977). "Evolution of massive stars with mass loss by stellar wind". Astronomy and Astrophysics. 61 (2): 251–259. Bibcode:1977A&A....61..251D.
Jump up ^ "The evolution of stars between 50 and 100 times the mass of the Sun". Royal Greenwich Observatory. Retrieved 2015-11-17.
Jump up ^ "Main Sequence Lifetime". Swinburne Astronomy Online Encyclopedia of Astronomy. Swinburne University of Technology.
Jump up ^ Pizzolato, N.; et al. (2001). "Subphotospheric convection and magnetic activity dependence on metallicity and age: Models and tests". Astronomy & Astrophysics. 373 (2): 597–607. Bibcode:2001A&A...373..597P. doi:10.1051/0004-6361:20010626.
Jump up ^ "Mass loss and Evolution". UCL Astrophysics Group. June 18, 2004. Archived from the original on 2004-11-22. Retrieved 2006-08-26.
Jump up ^ Schröder, K.-P.; Smith, Robert Connon (2008). "Distant future of the Sun and Earth revisited". Monthly Notices of the Royal Astronomical Society. 386 (1): 155–163. arXiv:0801.4031  . Bibcode:2008MNRAS.386..155S. doi:10.1111/j.1365-2966.2008.13022.x. See also Palmer, Jason (February 22, 2008). "Hope dims that Earth will survive Sun's death". NewScientist.com news service. Retrieved 2008-03-24.
Jump up ^ "The Evolution of Massive Stars and Type II Supernovae". Penn Stats College of Science. Retrieved 2016-01-05.
Jump up ^ Sneden, Christopher (February 8, 2001). "Astronomy: The age of the Universe". Nature. 409 (6821): 673–675. doi:10.1038/35055646.
Jump up ^ Liebert, J. (1980). "White dwarf stars". Annual Review of Astronomy and Astrophysics. 18 (2): 363–398. Bibcode:1980ARA&A..18..363L. doi:10.1146/annurev.aa.18.090180.002051.
^ Jump up to: a b c "Introduction to Supernova Remnants". Goddard Space Flight Center. April 6, 2006. Retrieved 2006-07-16.
Jump up ^ Fryer, C. L. (2003). "Black-hole formation from stellar collapse". Classical and Quantum Gravity. 20 (10): S73–S80. Bibcode:2003CQGra..20S..73F. doi:10.1088/0264-9381/20/10/309.
Jump up ^ "What is a galaxy? How many stars in a galaxy / the Universe?". Royal Greenwich Observatory. Retrieved 2006-07-18.
Jump up ^ Borenstein, Seth (December 1, 2010). "Universe's Star Count Could Triple". CBS News. Retrieved 2011-07-14.
Jump up ^ Van Dokkum, Pieter G; Conroy, Charlie (2010). "A substantial population of low-mass stars in luminous elliptical galaxies". Nature. 468 (7326): 940. arXiv:1009.5992  . Bibcode:2010Natur.468..940V. doi:10.1038/nature09578. PMID 21124316.
Jump up ^ "Hubble Finds Intergalactic Stars". Hubble News Desk. January 14, 1997. Retrieved 2006-11-06.
Jump up ^ Szebehely, Victor G.; Curran, Richard B. (1985). Stability of the Solar System and Its Minor Natural and Artificial Bodies. Springer. ISBN 90-277-2046-0.
Jump up ^ "Most Milky Way Stars Are Single" (Press release). Harvard-Smithsonian Center for Astrophysics. January 30, 2006. Retrieved 2006-07-16.
Jump up ^ 3.99 × 1013 km / (3 × 104 km/h × 24 × 365.25) = 1.5 × 105 years.
Jump up ^ Holmberg, J.; Flynn, C. (2000). "The local density of matter mapped by Hipparcos". Monthly Notices of the Royal Astronomical Society. 313 (2): 209–216. arXiv:astro-ph/9812404  . Bibcode:2000MNRAS.313..209H. doi:10.1046/j.1365-8711.2000.02905.x.
Jump up ^ "Astronomers: Star collisions are rampant, catastrophic". CNN News. June 2, 2000. Archived from the original on 2007-01-07. Retrieved 2014-01-21.
Jump up ^ Lombardi Jr., J. C.; et al. (2002). "Stellar Collisions and the Interior Structure of Blue Stragglers". The Astrophysical Journal. 568 (2): 939–953. arXiv:astro-ph/0107388  . Bibcode:2002ApJ...568..939L. doi:10.1086/339060.
^ Jump up to: a b H. E. Bond; E. P. Nelan; D. A. VandenBerg; G. H. Schaefer; D. Harmer (2013). "HD 140283: A Star in the Solar Neighborhood that Formed Shortly After the Big Bang". The Astrophysical Journal Letters. 765 (1): L12. arXiv:1302.3180  . Bibcode:2013ApJ...765L..12B. doi:10.1088/2041-8205/765/1/L12.
Jump up ^ Planck Collaboration (2015). "Planck 2015 results. XIII. Cosmological parameters (See Table 4 on page 31 of pfd)". Astronomy & Astrophysics. 594: A13. arXiv:1502.01589  . Bibcode:2016A&A...594A..13P. doi:10.1051/0004-6361/201525830.
Jump up ^ Naftilan, S. A.; Stetson, P. B. (July 13, 2006). "How do scientists determine the ages of stars? Is the technique really accurate enough to use it to verify the age of the universe?". Scientific American. Retrieved 2007-05-11.
Jump up ^ Laughlin, G.; Bodenheimer, P.; Adams, F. C. (1997). "The End of the Main Sequence". The Astrophysical Journal. 482 (1): 420–432. Bibcode:1997ApJ...482..420L. doi:10.1086/304125.
Jump up ^ Irwin, Judith A. (2007). Astrophysics: Decoding the Cosmos. John Wiley and Sons. p. 78. ISBN 0-470-01306-0.
Jump up ^ Fischer, D. A.; Valenti, J. (2005). "The Planet-Metallicity Correlation". The Astrophysical Journal. 622 (2): 1102–1117. Bibcode:2005ApJ...622.1102F. doi:10.1086/428383.
Jump up ^ "Signatures Of The First Stars". ScienceDaily. April 17, 2005. Retrieved 2006-10-10.
Jump up ^ Feltzing, S.; Gonzalez, G. (2000). "The nature of super-metal-rich stars: Detailed abundance analysis of 8 super-metal-rich star candidates". Astronomy & Astrophysics. 367 (1): 253–265. Bibcode:2001A&A...367..253F. doi:10.1051/0004-6361:20000477.
Jump up ^ Gray, David F. (1992). The Observation and Analysis of Stellar Photospheres. Cambridge University Press. pp. 413–414. ISBN 0-521-40868-7.
Jump up ^ Jørgensen, Uffe G. (1997), "Cool Star Models", in van Dishoeck, Ewine F., Molecules in Astrophysics: Probes and Processes, International Astronomical Union Symposia. Molecules in Astrophysics: Probes and Processes, 178, Springer Science & Business Media, p. 446, ISBN 079234538X
Jump up ^ "The Biggest Star in the Sky". ESO. March 11, 1997. Retrieved 2006-07-10.
Jump up ^ Ragland, S.; Chandrasekhar, T.; Ashok, N. M. (1995). "Angular Diameter of Carbon Star Tx-Piscium from Lunar Occultation Observations in the Near Infrared". Journal of Astrophysics and Astronomy. 16: 332. Bibcode:1995JApAS..16..332R.
Jump up ^ Dolan, Michelle M.; Mathews, Grant J.; Lam, Doan Duc; Lan, Nguyen Quynh; Herczeg, Gregory J.; Dearborn, David S. P. (2016). "Evolutionary Tracks for Betelgeuse". The Astrophysical Journal. 819: 7. arXiv:1406.3143v2  . Bibcode:2016ApJ...819....7D. doi:10.3847/0004-637X/819/1/7.
Jump up ^ Graham M. Harper; et al. (2008). "A NEW VLA-HIPPARCOS DISTANCE TO BETELGEUSE AND ITS IMPLICATIONS". The Astronomical Journal. 135 (4): 1430–1440. Bibcode:2008AJ....135.1430H. doi:10.1088/0004-6256/135/4/1430.
Jump up ^ Davis, Kate (December 1, 2000). "Variable Star of the Month—December, 2000: Alpha Orionis". AAVSO. Archived from the original on 2006-07-12. Retrieved 2006-08-13.
Jump up ^ Loktin, A. V. (September 2006). "Kinematics of stars in the Pleiades open cluster". Astronomy Reports. 50 (9): 714–721. Bibcode:2006ARep...50..714L. doi:10.1134/S1063772906090058.
Jump up ^ "Hipparcos: High Proper Motion Stars". ESA. September 10, 1999. Retrieved 2006-10-10.
Jump up ^ Johnson, Hugh M. (1957). "The Kinematics and Evolution of Population I Stars". Publications of the Astronomical Society of the Pacific. 69 (406): 54. Bibcode:1957PASP...69...54J. doi:10.1086/127012.
Jump up ^ Elmegreen, B.; Efremov, Y. N. (1999). "The Formation of Star Clusters". American Scientist. 86 (3): 264. Bibcode:1998AmSci..86..264E. doi:10.1511/1998.3.264. Archived from the original on March 23, 2005. Retrieved 2006-08-23.
Jump up ^ Brainerd, Jerome James (July 6, 2005). "X-rays from Stellar Coronas". The Astrophysics Spectator. Retrieved 2007-06-21.
Jump up ^ Berdyugina, Svetlana V. (2005). "Starspots: A Key to the Stellar Dynamo". Living Reviews. Retrieved 2007-06-21.
Jump up ^ Smith, Nathan (1998). "The Behemoth Eta Carinae: A Repeat Offender". Mercury Magazine. Astronomical Society of the Pacific. 27: 20. Archived from the original on 2006-09-27. Retrieved 2006-08-13.
Jump up ^ Weidner, C.; Kroupa, P. (February 11, 2004). "Evidence for a fundamental stellar upper mass limit from clustered star formation" (PDF). Monthly Notices of the Royal Astronomical Society. 348 (1): 187–191. arXiv:astro-ph/0310860  . Bibcode:2004MNRAS.348..187W. doi:10.1111/j.1365-2966.2004.07340.x.
Jump up ^ Hainich, R.; Rühling, U.; Todt, H.; Oskinova, L. M.; Liermann, A.; Gräfener, G.; Foellmi, C.; Schnurr, O.; Hamann, W. -R. (2014). "The Wolf-Rayet stars in the Large Magellanic Cloud". Astronomy & Astrophysics. 565: A27. arXiv:1401.5474  . Bibcode:2014A&A...565A..27H. doi:10.1051/0004-6361/201322696.
Jump up ^ Banerjee, Sambaran; Kroupa, Pavel; Oh, Seungkyung (October 21, 2012). "The emergence of super-canonical stars in R136-type starburst clusters". Monthly Notices of the Royal Astronomical Society. 426 (2): 1416–1426. arXiv:1208.0826  . Bibcode:2012MNRAS.426.1416B. doi:10.1111/j.1365-2966.2012.21672.x.
Jump up ^ "Ferreting Out The First Stars". Harvard-Smithsonian Center for Astrophysics. September 22, 2005. Retrieved 2006-09-05.
Jump up ^ Sobral, David; Matthee, Jorryt; Darvish, Behnam; Schaerer, Daniel; Mobasher, Bahram; Röttgering, Huub J. A.; Santos, Sérgio; Hemmati, Shoubaneh (4 June 2015). "Evidence For POPIII-Like Stellar Populations In The Most Luminous LYMAN-α Emitters At The Epoch Of Re-Ionisation: Spectroscopic Confirmation". The Astrophysical Journal. 808 (2): 139. arXiv:1504.01734  . Bibcode:2015ApJ...808..139S. doi:10.1088/0004-637x/808/2/139.
Jump up ^ Overbye, Dennis (17 June 2015). "Astronomers Report Finding Earliest Stars That Enriched Cosmos". The New York Times. Retrieved 17 June 2015.
Jump up ^ "2MASS J05233822-1403022". SIMBAD – Centre de Données astronomiques de Strasbourg. Retrieved 14 December 2013.
Jump up ^ Boss, Alan (April 3, 2001). "Are They Planets or What?". Carnegie Institution of Washington. Archived from the original on September 28, 2006. Retrieved 2006-06-08.
^ Jump up to: a b Shiga, David (August 17, 2006). "Mass cut-off between stars and brown dwarfs revealed". New Scientist. Archived from the original on November 14, 2006. Retrieved 2006-08-23.
Jump up ^ Leadbeater, Elli (August 18, 2006). "Hubble glimpses faintest stars". BBC. Retrieved 2006-08-22.
Jump up ^ "Flattest Star Ever Seen". ESO. June 11, 2003. Retrieved 2006-10-03.
Jump up ^ Fitzpatrick, Richard (February 13, 2006). "Introduction to Plasma Physics: A graduate course". The University of Texas at Austin. Archived from the original on 2010-01-04. Retrieved 2006-10-04.
Jump up ^ Villata, Massimo (1992). "Angular momentum loss by a stellar wind and rotational velocities of white dwarfs". Monthly Notices of the Royal Astronomical Society. 257 (3): 450–454. Bibcode:1992MNRAS.257..450V. doi:10.1093/mnras/257.3.450.
Jump up ^ "A History of the Crab Nebula". ESO. May 30, 1996. Retrieved 2006-10-03.
Jump up ^ Strobel, Nick (August 20, 2007). "Properties of Stars: Color and Temperature". Astronomy Notes. Primis/McGraw-Hill, Inc. Archived from the original on 2007-06-26. Retrieved 2007-10-09.
Jump up ^ Seligman, Courtney. "Review of Heat Flow Inside Stars". Self-published. Retrieved 2007-07-05.
^ Jump up to: a b "Main Sequence Stars". The Astrophysics Spectator. February 16, 2005. Retrieved 2006-10-10.
Jump up ^ Zeilik, Michael A.; Gregory, Stephan A. (1998). Introductory Astronomy & Astrophysics (4th ed.). Saunders College Publishing. p. 321. ISBN 0-03-006228-4.
Jump up ^ Koppes, Steve (June 20, 2003). "University of Chicago physicist receives Kyoto Prize for lifetime achievements in science". The University of Chicago News Office. Retrieved 2012-06-15.
Jump up ^ "The Colour of Stars". Australian Telescope Outreach and Education. Archived from the original on 2012-03-10. Retrieved 2006-08-13.
Jump up ^ "Astronomers Measure Mass of a Single Star—First Since the Sun". Hubble News Desk. July 15, 2004. Retrieved 2006-05-24.
Jump up ^ Garnett, D. R.; Kobulnicky, H. A. (2000). "Distance Dependence in the Solar Neighborhood Age-Metallicity Relation". The Astrophysical Journal. 532 (2): 1192–1196. arXiv:astro-ph/9912031  . Bibcode:2000ApJ...532.1192G. doi:10.1086/308617.
Jump up ^ Staff (January 10, 2006). "Rapidly Spinning Star Vega has Cool Dark Equator". National Optical Astronomy Observatory. Retrieved 2007-11-18.
Jump up ^ Michelson, A. A.; Pease, F. G. (2005). "Starspots: A Key to the Stellar Dynamo". Living Reviews in Solar Physics. Max Planck Society.
Jump up ^ Manduca, A.; Bell, R. A.; Gustafsson, B. (1977). "Limb darkening coefficients for late-type giant model atmospheres". Astronomy and Astrophysics. 61 (6): 809–813. Bibcode:1977A&A....61..809M.
Jump up ^ Chugainov, P. F. (1971). "On the Cause of Periodic Light Variations of Some Red Dwarf Stars". Information Bulletin on Variable Stars. 520: 1–3. Bibcode:1971IBVS..520....1C.
Jump up ^ "Magnitude". National Solar Observatory—Sacramento Peak. Archived from the original on 2008-02-06. Retrieved 2006-08-23.
^ Jump up to: a b "Luminosity of Stars". Australian Telescope Outreach and Education. Archived from the original on 2014-08-09. Retrieved 2006-08-13.
Jump up ^ Hoover, Aaron (January 15, 2004). "Star may be biggest, brightest yet observed". HubbleSite. Archived from the original on 2007-08-07. Retrieved 2006-06-08.
Jump up ^ "Faintest Stars in Globular Cluster NGC 6397". HubbleSite. August 17, 2006. Retrieved 2006-06-08.
Jump up ^ Smith, Gene (April 16, 1999). "Stellar Spectra". University of California, San Diego. Retrieved 2006-10-12.
Jump up ^ Fowler, A. (February 1891). "The Draper Catalogue of Stellar Spectra". Nature. 45 (1166): 427–8. Bibcode:1892Natur..45..427F. doi:10.1038/045427a0.
Jump up ^ Jaschek, Carlos; Jaschek, Mercedes (1990). The Classification of Stars. Cambridge University Press. pp. 31–48. ISBN 0-521-38996-8.
^ Jump up to: a b c MacRobert, Alan M. "The Spectral Types of Stars". Sky and Telescope. Retrieved 2006-07-19.
Jump up ^ "White Dwarf (wd) Stars". White Dwarf Research Corporation. Archived from the original on 2009-10-08. Retrieved 2006-07-19.
^ Jump up to: a b c d "Types of Variable". AAVSO. May 11, 2010. Retrieved 2010-08-20.
Jump up ^ "Cataclysmic Variables". NASA Goddard Space Flight Center. 2004-11-01. Retrieved 2006-06-08.
Jump up ^ Hansen, Carl J.; Kawaler, Steven D.; Trimble, Virginia (2004). Stellar Interiors. Springer. pp. 32–33. ISBN 0-387-20089-4.
^ Jump up to: a b c Schwarzschild, Martin (1958). Structure and Evolution of the Stars. Princeton University Press. ISBN 0-691-08044-5.
Jump up ^ "Formation of the High Mass Elements". Smoot Group. Retrieved 2006-07-11.
^ Jump up to: a b "What is a Star?". NASA. 2006-09-01. Retrieved 2006-07-11.
Jump up ^ "The Glory of a Nearby Star: Optical Light from a Hot Stellar Corona Detected with the VLT" (Press release). ESO. August 1, 2001. Retrieved 2006-07-10.
Jump up ^ Burlaga, L. F.; et al. (2005). "Crossing the Termination Shock into the Heliosheath: Magnetic Fields". Science. 309 (5743): 2027–2029. Bibcode:2005Sci...309.2027B. doi:10.1126/science.1117542. PMID 16179471.
^ Jump up to: a b c d Wallerstein, G.; et al. (1999). "Synthesis of the elements in stars: forty years of progress" (PDF). Reviews of Modern Physics. 69 (4): 995–1084. Bibcode:1997RvMP...69..995W. doi:10.1103/RevModPhys.69.995. Retrieved 2006-08-04.
Jump up ^ Girardi, L.; Bressan, A.; Bertelli, G.; Chiosi, C. (2000). "Evolutionary tracks and isochrones for low- and intermediate-mass stars: From 0.15 to 7 Msun, and from Z=0.0004 to 0.03". Astronomy and Astrophysics Supplement. 141 (3): 371–383. arXiv:astro-ph/9910164  . Bibcode:2000A&AS..141..371G. doi:10.1051/aas:2000126.
Jump up ^ Woosley, S. E.; Heger, A.; Weaver, T. A. (2002). "The evolution and explosion of massive stars". Reviews of Modern Physics. 74 (4): 1015–1071. Bibcode:2002RvMP...74.1015W. doi:10.1103/RevModPhys.74.1015.
Jump up ^ 11.5 days is 0.0315 years.
Further reading
Pickover, Cliff (2001). The Stars of Heaven. Oxford University Press. ISBN 0-19-514874-6.
Gribbin, John; Gribbin, Mary (2001). Stardust: Supernovae and Life—The Cosmic Connection. Yale University Press. ISBN 0-300-09097-8.
Hawking, Stephen (1988). A Brief History of Time. Bantam Books. ISBN 0-553-17521-1.
External links
Look up star in Wiktionary, the free dictionary.
Wikimedia Commons has media related to Stars.
Kaler, James. "Portraits of Stars and their Constellations". University of Illinois. Retrieved 2010-08-20.
"Query star by identifier, coordinates or reference code". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-08-20.
"How To Decipher Classification Codes". Astronomical Society of South Australia. Retrieved 2010-08-20.
Prialnick, Dina; et al. (2001). "Stars: Stellar Atmospheres, Structure, & Evolution". University of St. Andrews. Retrieved 2010-08-20.
hide
v
t
e
Star
Formation
Accretion
Molecular cloud
Bok globule
Young stellar object
Protostar
Pre-main-sequence star
Herbig Ae/Be
Orion
T Tauri
FU Orionis
Herbig–Haro object
Hayashi track
Henyey track
Evolution
Main sequence
Red-giant branch
Horizontal branch
Red clump
Asymptotic giant branch
Protoplanetary nebula
Planetary nebula
PG1159 star
Dredge-up
Instability strip
Luminous blue variable
Blue straggler
Stellar population
Supernova
Supernova impostor
Hypernova
Hertzsprung–Russell diagram
Color–color diagram
Luminosity class
Subdwarf
Dwarf
Blue
Red
White
Yellow
Brown
Subgiant
Giant
Blue
Red
Yellow
Bright giant
Supergiant
Blue
Red
Yellow
Hypergiant
Yellow
Spectral
classification
O
B
A
F
G
K
M
WR
Be
OB
Subdwarf O
Subdwarf B
Late-type
Chemically peculiar
Am
Ap/Bp
Oscillating
Barium
Carbon
CH
CN
Extreme helium
Lambda Boötis
Lead
HgMn
S
Technetium
Shell
Remnants
White dwarf
Helium planet
Neutron star
Radio-quiet
Pulsar
Binary
X-ray
Magnetar
Stellar black hole
X-ray binary
Burster
Hypothetical stars
Boson star
Black dwarf
Exotic
Electroweak star
Quark
Strange
Preon
Planck
Dark matter star
Dark-energy star
Black star
Gravastar
Frozen star
Q star
Quasi-star
Thorne–Żytkow object
Iron star
Blitzar
Nucleosynthesis
Deuterium burning
Lithium burning
Proton–proton chain
CNO cycle
Helium flash
Triple-alpha process
Alpha process
Carbon burning
Neon burning
Oxygen burning
Silicon burning
S-process
R-process
Fusor
Nova
Symbiotic
Remnant
Luminous red nova
Structure
Core
Convection zone
Microturbulence
Oscillations
Radiation zone
Atmosphere
Photosphere
Starspot
Chromosphere
Corona
Stellar wind
Bubble
Bipolar outflow
Accretion disk
Asteroseismology
Helioseismology
Eddington luminosity
Kelvin–Helmholtz mechanism
Properties
Designation
Dynamics
Effective temperature
Kinematics
Magnetic field
Absolute magnitude
Mass
Metallicity
Rotation
UBV color
Variable star
Mira variable
Star systems
Binary
Contact
Common envelope
Eclipsing
Symbiotic
Multiple
Star cluster
Open cluster
Globular cluster
Super star cluster
Planetary system
Earth's Solar System
Earth-centric
observation of
Pole star
Circumpolar star
Constellation
Asterism
Magnitude
Apparent
Extinction
Photographic
Radial velocity
Proper motion
Parallax
Photometric-standard star
Lists
Star names
Arabic
Chinese
Extremes
Most massive
Highest temperature
Largest volume
Smallest volume
Brightest
Historical
Most luminous
Nearest
Nearest bright
Stars with exoplanets
Brown dwarfs
White dwarfs
Milky Way novae
Notable supernovae
Supernova candidates
Supernova remnants
Planetary nebulae
Timeline of stellar astronomy
Related articles
Substellar object
Brown dwarf
Sub-brown dwarf
Planet
Galactic year
Galaxy
Supercluster
Guest star
Gravity
Icarus (most distant individual star)
Intergalactic star
Infrared dark cloud
Starfield
Category:Stars · Star portal
show
v
t
e
Variable stars
Pulsating
Cepheids and
cepheid-like
Classical
Type II (BL Herculis, W Virginis, RV Tauri)
RR Lyrae
Delta Scuti
Rapidly oscillating Ap
SX Phoenicis
Blue-white with
early spectra
Alpha Cygni
Beta Cephei
Slowly pulsating B
PV Telescopii
Blue large-amplitude pulsator
Long-period
Mira
Semiregular
Slow irregular
Other
Gamma Doradus
Solar-like oscillations
White dwarf
Eruptive
Protostar and PMS
FU Orionis
Herbig Ae/Be
Orion (T Tauri)
Giants and
supergiants
Luminous blue variable
R Coronae Borealis (DY Persei)
Yellow hypergiant
Eruptive binary
Double periodic
FS Canis Majoris
RS Canum Venaticorum
Other
Flare
Gamma Cassiopeiae
Lambda Eridani
Wolf–Rayet
Cataclysmic
AM Canum Venaticorum
Dwarf nova
Luminous red nova
Nova
Polar
Intermediate polar
Supernova
Hypernova
SW Sextantis
Symbiotic
Symbiotic nova
Z Andromedae
Rotating
Non-spherical
Rotating ellipsoidal
Stellar spots
BY Draconis
FK Comae Berenices
Magnetic fields
Alpha² Canum Venaticorum
Pulsar
SX Arietis
Eclipsing
Algol
Beta Lyrae
Planetary transit
W Ursae Majoris
Star portal
show
v
t
e
Supernovae
Classes
Type Ia
Type Ib and Ic
Type II (IIP, IIL, IIn, and IIb)

Physics of
Calcium-rich supernovae
Carbon detonation
Pair-instability supernova
Phillips relationship
P-nuclei
P-process
R-process
Supernova nucleosynthesis
Supernova neutrinos
Related
Supernova impostor
Pulsational pair-instability supernova
Foe
Gamma-ray burst
Failed supernova
Hypernova
Kilonova
Nova
Symbiotic nova
Luminous red nova
Near-Earth supernova
Pulsar kick
Quark-nova
Progenitors
Hypergiant
Yellow
Luminous blue variable
Supergiant
Blue
Red
Yellow
White dwarf
Related links
Wolf–Rayet star
Remnants
Supernova remnant
Pulsar wind nebula
Neutron star
Pulsar
Magnetar
Related links
Stellar black hole
Related links
Compact star
Quark star
Exotic star
Zombie star
Local Bubble
Superbubble
Orion–Eridanus
Discovery
Guest star
History of supernova observation
Timeline of white dwarfs, neutron stars, and supernovae
Lists
Candidates
Notable
Massive stars
Most distant
Remnants
In fiction
Notable
Barnard's Loop
Cassiopeia A
Crab
Crab Nebula
iPTF14hls
Tycho's
Kepler's
SN 1987A
SN 185
SN 1006
SN 2003fg
Remnant G1.9+0.3
SN 2007bi
SN 2011fe
SN 2014J
SN Refsdal
Vela Remnant
Research
ASAS-SN
Calán/Tololo Survey
High-Z Supernova Search Team
Katzman Automatic Imaging Telescope
Monte Agliale Supernovae and Asteroid Survey
Nearby Supernova Factory
Sloan Supernova Survey
Supernova/Acceleration Probe
Supernova Cosmology Project
Supernova Early Warning System
Supernova Legacy Survey
Texas Supernova Search
Book:Supernovae
Category:Supernovae
Commons:Supernovae
show
v
t
e
Big History
Themes and subjects
Chronology of the universe
Cosmic evolution
Deep time
Time scales
Goldilocks principle
Modernity
Eight thresholds
1: Creation - Big Bang and cosmogony
2: Stars - creation of stars
3: Elements - creation of chemical elements inside dying stars
4: Planets - formation of planets
5: Life - abiogenesis and evolution of life
6: Humans - development of Homo sapiens
Paleolithic era
7: Agriculture - Agricultural Revolution
8: Modernity - modern era
Web-based education
Big History Project
Crash Course Big History
ChronoZoom
Notable people
Walter Alvarez
Cynthia Stokes Brown
Eric Chaisson
David Christian
Bill Gates
Carl Sagan
Graeme Snooks
Jimmy Wales
Bill Wurtz
Authority control
GND: 4057342-4
LCCN: sh85127415
NDL: 00566683
Retrieved from "https://en.wikipedia.org/w/index.php?title=Star&oldid=854238228"
Categories:
Light sources
Stars
Stellar astronomy
Hidden categories:
CS1 maint: Explicit use of et al.
Wikipedia indefinitely semi-protected pages
Featured articles
All articles with unsourced statements
Articles with unsourced statements from August 2018
Wikipedia articles with GND identifiers
Wikipedia articles with LCCN identifiers
Wikipedia articles with NDL identifiers
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
View source
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Wikiquote
Languages
Afrikaans
Alemannisch
አማርኛ
العربية
Aragonés
ܐܪܡܝܐ
Armãneashti
Asturianu
Avañe'ẽ
Aymar aru
Azərbaycanca
تۆرکجه
বাংলা
Bahasa Banjar
Bân-lâm-gú
Башҡортса
Беларуская
Беларуская (тарашкевіца)
भोजपुरी
Български
Boarisch
Bosanski
Brezhoneg
Буряад
Català
Чӑвашла
Cebuano
Čeština
ChiShona
Cymraeg
Dansk
Davvisámegiella
Deutsch
Eesti
Ελληνικά
Emiliàn e rumagnòl
Эрзянь
Español
Esperanto
Estremeñu
Euskara
فارسی
Fiji Hindi
Føroyskt
Français
Frysk
Furlan
Gaeilge
Gaelg
Gàidhlig
Galego
Gĩkũyũ
客家語/Hak-kâ-ngî
Хальмг
한국어
Հայերեն
हिन्दी
Hrvatski
Ido
Ilokano
Bahasa Indonesia
Interlingua
ᐃᓄᒃᑎᑐᑦ/inuktitut
Ирон
IsiXhosa
Íslenska
Italiano
עברית
Basa Jawa
ಕನ್ನಡ
Kapampangan
Къарачай-малкъар
ქართული
Қазақша
Kiswahili
Kreyòl ayisyen
Kurdî
Кыргызча
Кырык мары
Ladino
Лезги
Latina
Latviešu
Lëtzebuergesch
Lietuvių
Limburgs
Lingála
La .lojban.
Lumbaart
Magyar
Македонски
Malagasy
മലയാളം
मराठी
მარგალური
مصرى
مازِرونی
Bahasa Melayu
Mìng-dĕ̤ng-ngṳ̄
Mirandés
Монгол
မြန်မာဘာသာ
Nāhuatl
Dorerin Naoero
Nederlands
नेपाली
नेपाल भाषा
日本語
Napulitano
Нохчийн
Nordfriisk
Norfuk / Pitkern
Norsk
Norsk nynorsk
Nouormand
Novial
Occitan
Oʻzbekcha/ўзбекча
ਪੰਜਾਬੀ
پنجابی
Patois
Picard
Piemontèis
Plattdüütsch
Polski
Português
Qaraqalpaqsha
Ripoarisch
Română
Romani
Runa Simi
Русиньскый
Русский
Саха тыла
संस्कृतम्
Sardu
Scots
Seeltersk
Shqip
Sicilianu
සිංහල
Simple English
سنڌي
Slovenčina
Slovenščina
Словѣньскъ / ⰔⰎⰑⰂⰡⰐⰠⰔⰍⰟ
Ślůnski
Soomaaliga
کوردی
Српски / srpski
Srpskohrvatski / српскохрватски
Basa Sunda
Suomi
Svenska
Tagalog
தமிழ்
Taqbaylit
Татарча/tatarça
తెలుగు
ไทย
Тоҷикӣ
ᏣᎳᎩ
Tsetsêhestâhese
Türkçe
Türkmençe
Удмурт
Українська
اردو
Vèneto
Vepsän kel’
Tiếng Việt
Võro
Walon
文言
West-Vlams
Winaray
吴语
ייִדיש
Yorùbá
粵語
Zazaki
Žemaitėška
中文
डोटेली
ГӀалгӀай
Kabɩyɛ
Lingua Franca Nova
178 more
Edit links
This page was last edited on 9 August 2018, at 22:08 (UTC).
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

key: html

type: local

value: div

attrs: id class

values: mw-page-base noprint

values: mw-head-base noprint

value: a

value: img

attrs: alt src width height srcset data-file-width data-file-height

values: This is a featured article. Click here for more information.

attrs: href title

values: mw-indicator-featured-star mw-indicator

values: mw-indicator-pp-default mw-indicator

attrs: id class lang

values: firstHeading firstHeading en

values: siteSub noprint

attrs: class href

values: mw-jump-link #mw-head

values: mw-jump-link #p-search

attrs: href class title

values:
/wiki/Star_(disambiguation)
mw-disambig
Star (disambiguation)

attrs: role class

values:
note
hatnote navigation-not-searchable

value: p

attrs: alt src width height class srcset data-file-width data-file-height

attrs: href class

values:
/wiki/Stellar_designation
mw-redirect
Stellar designation

values:
/wiki/Stellar_remnant
mw-redirect
Stellar remnant

values: checkbox button toctogglecheckbox toctogglecheckbox display:none

values:
/wiki/Heavenly_sphere
mw-redirect
Heavenly sphere

values:
/wiki/Astronomy_in_medieval_Islam
mw-redirect
Astronomy in medieval Islam

values:
/wiki/Abu_Rayhan_Biruni
mw-redirect
Abu Rayhan Biruni

values:
/wiki/Extrasolar_planet
mw-redirect
Extrasolar planet

values:
/wiki/Greek_philosophy
mw-redirect
Greek philosophy

values:
/wiki/Alpha_Centauri_B
mw-redirect
Alpha Centauri B

values:
/wiki/Spectroscopic_binary
mw-redirect
Spectroscopic binary

values:
/wiki/Mizar_(star)
mw-redirect
Mizar (star)

values:
/wiki/Visual_magnitude
mw-redirect
Visual magnitude

values:
/wiki/Hertzsprung-Russell_diagram
mw-redirect
Hertzsprung-Russell diagram

values:
/wiki/Local_Supercluster
mw-redirect
Local Supercluster

values:
/wiki/Icarus_(star)
mw-redirect
Icarus (star)

values:
/wiki/Arab_language
mw-redirect
Arab language

values:
/wiki/Latin_language
mw-redirect
Latin language

values:
/wiki/Commercial_enterprise
mw-redirect
Commercial enterprise

values:
/wiki/Deceptive_practice
mw-redirect
Deceptive practice

values: New York City Department of Consumer Affairs

values:
/wiki/Gravitational_Constant
mw-redirect
Gravitational Constant

values:
/wiki/Red_giant_branch
mw-redirect
Red giant branch

values:
/wiki/Helium_fusion
mw-redirect
Helium fusion

values:
/wiki/Blue_supergiant
mw-redirect
Blue supergiant

values:
/wiki/Red_supergiant
mw-redirect
Red supergiant

values:
/wiki/Wolf-Rayet_star
mw-redirect
Wolf-Rayet star

values:
/wiki/Electron-degenerate_matter
mw-redirect
Electron-degenerate matter

values:
/wiki/Neutron-degenerate_matter
mw-redirect
Neutron-degenerate matter

values:
/wiki/Contact_binaries
mw-redirect
Contact binaries

values:
/wiki/Disc_(galaxy)
mw-redirect
Disc (galaxy)

values:
/wiki/Galactic_spheroid
mw-redirect
Galactic spheroid

values:
/wiki/Peculiar_star
mw-redirect
Peculiar star

values:
/wiki/Rare_earth_element
mw-redirect
Rare earth element

values:
/wiki/Orion_constellation
mw-redirect
Orion constellation

values:
/wiki/Doppler_shift
mw-redirect
Doppler shift

values:
/wiki/Space_velocity_(astronomy)
mw-redirect
Space velocity (astronomy)

values:
/wiki/Stellar_flare
mw-redirect
Stellar flare

values:
/wiki/Population_III_stars
mw-redirect
Population III stars

values:
/wiki/Absorption_line
mw-redirect
Absorption line

values: This claim needs references to reliable sources. (August 2018)

values:
noprint Inline-Template Template-Fact
white-space:nowrap;

values:
/wiki/Main_sequence_star
mw-redirect
Main sequence star

values:
/wiki/Degenerate_star
mw-redirect
Degenerate star

values:
/wiki/Crab_nebula
mw-redirect
Crab nebula

values:
/wiki/Electromagnetic_energy
mw-redirect
Electromagnetic energy

values:
/wiki/Interstellar_dust
mw-redirect
Interstellar dust

values:
wikitable
float: right; margin-left: 1em;

values:
/wiki/Logarithmic_units
mw-redirect
Logarithmic units

values:
/wiki/Second_magnitude_star
mw-redirect
Second magnitude star

values:
/wiki/Sixth_magnitude_star
mw-redirect
Sixth magnitude star

values: {\displaystyle \Delta {m}=m_{\mathrm {f} }-m_{\mathrm {b} }}

values: vertical-align: -0.671ex; width:15.986ex; height:2.509ex;

values: \Delta {m}=m_{\mathrm {f} }-m_{\mathrm {b} }

values: {\displaystyle 2.512^{\Delta {m}}=\Delta {L}}

values: vertical-align: -0.338ex; width:14.958ex; height:2.676ex;

values: float: right; text-align: center; margin-left: 1em;

values:
/wiki/Main_sequence_stars
mw-redirect
Main sequence stars

values:
/wiki/Yellow_dwarf
mw-redirect
Yellow dwarf

values:
/wiki/Blue-white_main_sequence_star
mw-redirect
Blue-white main sequence star

values:
wikitable
float: left; margin-right: 0.5em;

values: display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle

values: margin:0.5em 0 0.5em 1em;border:solid #aaa 1px

values:
/wiki/Exoplanet_host_stars
mw-redirect
Exoplanet host stars

values:
/wiki/List_of_largest_known_stars
mw-redirect
List of largest known stars

values:
/wiki/Stellar_astronomy
mw-redirect
Stellar astronomy

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em;

values:
nofollow
external text
//doi.org/10.1086/191565

values:
nofollow
external text
http://www.gutenberg.org/ebooks/8172

values:
nofollow
external text
//doi.org/10.1086/125409

values:
nofollow
external text
//doi.org/10.1086/125410

values:
nofollow
external text
//doi.org/10.1086/349558

values:
nofollow
external text
//doi.org/10.1038/001331a0

values:
nofollow
external text
//doi.org/10.1086/142603

values:
nofollow
external text
//doi.org/10.1086/346274

values:
nofollow
external text
//arxiv.org/abs/1706.10279

attrs: alt src title width height srcset data-file-width data-file-height

values: Category:CS1 maint: Explicit use of et al.

values:
nofollow
http://www.iau.org/public/naming/
external text

values: Students for the Exploration and Development of Space

values:
nofollow
external text
http://www.bl.uk/names.html

values:
nofollow
external text
//arxiv.org/abs/1605.09788

values:
nofollow
external text
//arxiv.org/abs/astro-ph/0301540

values:
nofollow
external text
//doi.org/10.1086/155302

values:
nofollow
external text
//arxiv.org/abs/1208.1471

values:
nofollow
external text
//doi.org/10.1086/190603

values:
nofollow
external text
//doi.org/10.1086/173407

values:
nofollow
external text
//arxiv.org/abs/astro-ph/0203437

values:
nofollow
external text
//doi.org/10.1086/340797

values: Monthly Notices of the Royal Astronomical Society

values:
nofollow
external text
//arxiv.org/abs/0801.4031

values:
nofollow
external text
//doi.org/10.1038/35055646

values:
nofollow
external text
//arxiv.org/abs/1009.5992

values:
nofollow
external text
//doi.org/10.1038/nature09578

values:
/wiki/PubMed_Identifier
mw-redirect
PubMed Identifier

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/21124316

values:
nofollow
external text
//arxiv.org/abs/astro-ph/9812404

values:
nofollow
external text
//arxiv.org/abs/astro-ph/0107388

values:
nofollow
external text
//doi.org/10.1086/339060

values:
/wiki/The_Astrophysical_Journal_Letters
mw-redirect
The Astrophysical Journal Letters

values:
nofollow
external text
//arxiv.org/abs/1302.3180

values:
nofollow
external text
//arxiv.org/abs/1502.01589

values:
nofollow
external text
//doi.org/10.1086/304125

values:
nofollow
external text
//doi.org/10.1086/428383

values:
nofollow
http://www.eso.org/public/news/eso9706/
external text

values:
nofollow
external text
//arxiv.org/abs/1406.3143v2

values:
nofollow
external text
//doi.org/10.1086/127012

values:
nofollow
external text
//doi.org/10.1511/1998.3.264

values:
nofollow
external text
//arxiv.org/abs/astro-ph/0310860

values:
nofollow
external text
//arxiv.org/abs/1401.5474

values:
nofollow
external text
//arxiv.org/abs/1208.0826

values:
nofollow
external text
//arxiv.org/abs/1504.01734

values: Centre de Données astronomiques de Strasbourg

values:
nofollow
http://www.eso.org/public/news/eso0316/
external text

values:
nofollow
external text
//doi.org/10.1093/mnras/257.3.450

values:
nofollow
external text
//arxiv.org/abs/astro-ph/9912031

values:
nofollow
external text
//doi.org/10.1086/308617

values:
nofollow
external text
//doi.org/10.1038/045427a0

values:
nofollow
external text
http://www.aavso.org/types-variables

values:
nofollow
http://www.eso.org/public/news/eso0127/
external text

values:
nofollow
external text
//doi.org/10.1126/science.1117542

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/16179471

values:
nofollow
external text
//doi.org/10.1103/RevModPhys.69.995

values:
nofollow
external text
//arxiv.org/abs/astro-ph/9910164

values:
nofollow
external text
//doi.org/10.1051/aas%3A2000126

values:
nofollow
external text
//doi.org/10.1103/RevModPhys.74.1015

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

values:
/wiki/Cliff_Pickover
mw-redirect
Cliff Pickover

values:
row
navbox-group
text-align: center;;width:1%

values:
/wiki/Yellow_supergiant
mw-redirect
Yellow supergiant

values:
/wiki/Late-type_star
mw-redirect
Late-type star

values:
/wiki/Deuterium_burning
mw-redirect
Deuterium burning

values:
/wiki/Eclipsing_binary
mw-redirect
Eclipsing binary

values: nowraplinks hlist collapsible uncollapsed navbox-inner mw-collapsible mw-made-collapsible

values:
/wiki/Slowly_pulsating_B_star
mw-redirect
Slowly pulsating B star

values:
/wiki/Gamma_Cassiopeiae_variable
mw-redirect
Gamma Cassiopeiae variable

values:
/wiki/Symbiotic_star
mw-redirect
Symbiotic star

values:
/wiki/Z_Andromedae_variable
mw-redirect
Z Andromedae variable

values:
/wiki/FK_Comae_Berenices_variable
mw-redirect
FK Comae Berenices variable

values:
/wiki/Planetary_transit_variable
mw-redirect
Planetary transit variable

values: nowraplinks hlist collapsible autocollapse navbox-inner mw-collapsible mw-made-collapsible mw-collapsed

values:
navbox-image
9
width:1px;padding:0px 0px 0px 2px

values:
/wiki/Supernova_neutrino
mw-redirect
Supernova neutrino

values: Timeline of white dwarfs, neutron stars, and supernovae

values: Monte Agliale Supernovae and Asteroid Survey

values:
/wiki/Supernova/Acceleration_Probe
mw-redirect
Supernova/Acceleration Probe

values: navigation navbox Supernovae padding:3px

attrs: alt src width height style srcset data-file-width data-file-height

values:
nofollow
external text
https://d-nb.info/gnd/4057342-4

values: Category:Wikipedia indefinitely semi-protected pages

values: Category:All articles with unsourced statements

values: Category:Articles with unsourced statements from August 2018

values: Category:Wikipedia articles with GND identifiers

values: Category:Wikipedia articles with LCCN identifiers

values: Category:Wikipedia articles with NDL identifiers

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Star
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values:
This page is protected.
You can view its source [ctrl-alt-e]

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values: portal navigation p-wikibase-otherprojects p-wikibase-otherprojects-label

values:
https://af.wikipedia.org/wiki/Ster
Ster – Afrikaans
af
af
interlanguage-link-target

values: interlanguage-link interwiki-af badge-Q17437796 badge-featuredarticle

values:
https://als.wikipedia.org/wiki/Stern
Stern – Alemannisch
als
als
interlanguage-link-target

values:
interlanguage-link interwiki-als
display: none;

values:
interlanguage-link interwiki-am
display: none;

values:
interlanguage-link interwiki-ar
display: none;

values:
https://an.wikipedia.org/wiki/Estrela
Estrela – Aragonese
an
an
interlanguage-link-target

values:
interlanguage-link interwiki-an
display: none;

values:
interlanguage-link interwiki-arc
display: none;

values:
interlanguage-link interwiki-roa-rup
display: none;

values:
https://ast.wikipedia.org/wiki/Estrella
Estrella – Asturian
ast
ast
interlanguage-link-target

values:
interlanguage-link interwiki-ast
display: none;

values:
https://gn.wikipedia.org/wiki/Mbyja
Mbyja – Guarani
gn
gn
interlanguage-link-target

values:
interlanguage-link interwiki-gn
display: none;

values:
https://ay.wikipedia.org/wiki/Warawara
Warawara – Aymara
ay
ay
interlanguage-link-target

values:
interlanguage-link interwiki-ay
display: none;

values:
https://az.wikipedia.org/wiki/Ulduz
Ulduz – Azerbaijani
az
az
interlanguage-link-target

values:
interlanguage-link interwiki-az
display: none;

values:
interlanguage-link interwiki-azb
display: none;

values:
interlanguage-link interwiki-bn
display: none;

values:
https://bjn.wikipedia.org/wiki/Bintang
Bintang – Banjar
bjn
bjn
interlanguage-link-target

values:
interlanguage-link interwiki-bjn
display: none;

values:
interlanguage-link interwiki-zh-min-nan
display: none;

values: Йондоҙҙар – Bashkir

values:
interlanguage-link interwiki-ba
display: none;

values:
interlanguage-link interwiki-be
display: none;

values: Зорка – Belarusian (Taraškievica orthography)

values:
interlanguage-link interwiki-be-x-old
display: none;

values:
interlanguage-link interwiki-bh
display: none;

values:
interlanguage-link interwiki-bg
display: none;

values:
https://bar.wikipedia.org/wiki/Stean
Stean – Bavarian
bar
bar
interlanguage-link-target

values:
interlanguage-link interwiki-bar
display: none;

values:
https://bs.wikipedia.org/wiki/Zvijezda
Zvijezda – Bosnian
bs
bs
interlanguage-link-target

values:
interlanguage-link interwiki-bs
display: none;

values:
https://br.wikipedia.org/wiki/Steredenn
Steredenn – Breton
br
br
interlanguage-link-target

values:
interlanguage-link interwiki-br
display: none;

values:
interlanguage-link interwiki-bxr
display: none;

values:
https://ca.wikipedia.org/wiki/Estrella
Estrella – Catalan
ca
ca
interlanguage-link-target

values:
interlanguage-link interwiki-ca
display: none;

values: Çăлтăр – Chuvash

values:
interlanguage-link interwiki-cv
display: none;

values:
https://ceb.wikipedia.org/wiki/Bitoon
Bitoon – Cebuano
ceb
ceb
interlanguage-link-target

values:
interlanguage-link interwiki-ceb
display: none;

values:
interlanguage-link interwiki-cs
display: none;

values:
https://sn.wikipedia.org/wiki/Nyenyedzi
Nyenyedzi – Shona
sn
sn
interlanguage-link-target

values:
interlanguage-link interwiki-sn
display: none;

values:
https://cy.wikipedia.org/wiki/Seren
Seren – Welsh
cy
cy
interlanguage-link-target

values:
interlanguage-link interwiki-cy
display: none;

values:
https://da.wikipedia.org/wiki/Stjerne
Stjerne – Danish
da
da
interlanguage-link-target

values: interlanguage-link interwiki-da badge-Q17559452 badge-recommendedarticle

values:
interlanguage-link interwiki-se
display: none;

values:
https://de.wikipedia.org/wiki/Stern
Stern – German
de
de
interlanguage-link-target

values: interlanguage-link interwiki-de badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-et
display: none;

values: Αστέρας – Greek

values:
interlanguage-link interwiki-el
display: none;

values:
interlanguage-link interwiki-eml
display: none;

values: Теште – Erzya

values:
interlanguage-link interwiki-myv
display: none;

values:
https://es.wikipedia.org/wiki/Estrella
Estrella – Spanish
es
es
interlanguage-link-target

values:
interlanguage-link interwiki-es
display: none;

values:
https://eo.wikipedia.org/wiki/Stelo
Stelo – Esperanto
eo
eo
interlanguage-link-target

values:
interlanguage-link interwiki-eo
display: none;

values:
https://ext.wikipedia.org/wiki/Estrella
Estrella – Extremaduran
ext
ext
interlanguage-link-target

values:
interlanguage-link interwiki-ext
display: none;

values:
https://eu.wikipedia.org/wiki/Izar
Izar – Basque
eu
eu
interlanguage-link-target

values: interlanguage-link interwiki-eu badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-fa
display: none;

values:
https://hif.wikipedia.org/wiki/Tara
Tara – Fiji Hindi
hif
hif
interlanguage-link-target

values:
interlanguage-link interwiki-hif
display: none;

values:
interlanguage-link interwiki-fo
display: none;

values:
interlanguage-link interwiki-fr
display: none;

values:
https://fy.wikipedia.org/wiki/Stjer
Stjer – Western Frisian
fy
fy
interlanguage-link-target

values:
interlanguage-link interwiki-fy
display: none;

values:
https://fur.wikipedia.org/wiki/Stele
Stele – Friulian
fur
fur
interlanguage-link-target

values:
interlanguage-link interwiki-fur
display: none;

values:
interlanguage-link interwiki-ga
display: none;

values:
https://gv.wikipedia.org/wiki/Rollage
Rollage – Manx
gv
gv
interlanguage-link-target

values:
interlanguage-link interwiki-gv
display: none;

values:
https://gd.wikipedia.org/wiki/Reul
Reul – Scottish Gaelic
gd
gd
interlanguage-link-target

values:
interlanguage-link interwiki-gd
display: none;

values:
interlanguage-link interwiki-gl
display: none;

values:
https://ki.wikipedia.org/wiki/Njata
Njata – Kikuyu
ki
ki
interlanguage-link-target

values:
interlanguage-link interwiki-ki
display: none;

values:
interlanguage-link interwiki-hak
display: none;

values:
interlanguage-link interwiki-xal
display: none;

values: interlanguage-link interwiki-ko badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-hy
display: none;

values: तारा – Hindi

values:
interlanguage-link interwiki-hi
display: none;

values:
https://hr.wikipedia.org/wiki/Zvijezda
Zvijezda – Croatian
hr
hr
interlanguage-link-target

values:
interlanguage-link interwiki-hr
display: none;

values:
https://io.wikipedia.org/wiki/Stelo
Stelo – Ido
io
io
interlanguage-link-target

values:
interlanguage-link interwiki-io
display: none;

values:
https://ilo.wikipedia.org/wiki/Bituen
Bituen – Iloko
ilo
ilo
interlanguage-link-target

values:
interlanguage-link interwiki-ilo
display: none;

values:
https://id.wikipedia.org/wiki/Bintang
Bintang – Indonesian
id
id
interlanguage-link-target

values:
interlanguage-link interwiki-id
display: none;

values:
https://ia.wikipedia.org/wiki/Stella
Stella – Interlingua
ia
ia
interlanguage-link-target

values:
interlanguage-link interwiki-ia
display: none;

values:
interlanguage-link interwiki-iu
display: none;

values: Стъалы – Ossetic

values:
interlanguage-link interwiki-os
display: none;

values:
interlanguage-link interwiki-xh
display: none;

values:
interlanguage-link interwiki-is
display: none;

values:
https://it.wikipedia.org/wiki/Stella
Stella – Italian
it
it
interlanguage-link-target

values: interlanguage-link interwiki-it badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-he
display: none;

values:
https://jv.wikipedia.org/wiki/Lintang
Lintang – Javanese
jv
jv
interlanguage-link-target

values:
interlanguage-link interwiki-jv
display: none;

values: ನಕ್ಷತ್ರ – Kannada

values:
interlanguage-link interwiki-kn
display: none;

values:
https://pam.wikipedia.org/wiki/Batuin
Batuin – Pampanga
pam
pam
interlanguage-link-target

values:
interlanguage-link interwiki-pam
display: none;

values:
interlanguage-link interwiki-krc
display: none;

values: ვარსკვლავი – Georgian

values: interlanguage-link interwiki-ka badge-Q17437796 badge-featuredarticle

values: Жұлдыз – Kazakh

values: interlanguage-link interwiki-kk badge-Q17437796 badge-featuredarticle

values:
https://sw.wikipedia.org/wiki/Nyota
Nyota – Swahili
sw
sw
interlanguage-link-target

values:
interlanguage-link interwiki-sw
display: none;

values:
https://ht.wikipedia.org/wiki/Etwal
Etwal – Haitian Creole
ht
ht
interlanguage-link-target

values:
interlanguage-link interwiki-ht
display: none;

values:
https://ku.wikipedia.org/wiki/St%C3%AAr
Stêr – Kurdish
ku
ku
interlanguage-link-target

values:
interlanguage-link interwiki-ku
display: none;

values: Жылдыз – Kyrgyz

values:
interlanguage-link interwiki-ky
display: none;

values: Шӹдӹр (астрономи) – Western Mari

values:
interlanguage-link interwiki-mrj
display: none;

values:
https://lad.wikipedia.org/wiki/Estreya
Estreya – Ladino
lad
lad
interlanguage-link-target

values:
interlanguage-link interwiki-lad
display: none;

values:
interlanguage-link interwiki-lez
display: none;

values:
https://la.wikipedia.org/wiki/Stella
Stella – Latin
la
la
interlanguage-link-target

values:
interlanguage-link interwiki-la
display: none;

values:
https://lv.wikipedia.org/wiki/Zvaigzne
Zvaigzne – Latvian
lv
lv
interlanguage-link-target

values:
interlanguage-link interwiki-lv
display: none;

values:
https://lb.wikipedia.org/wiki/St%C3%A4r
Stär – Luxembourgish
lb
lb
interlanguage-link-target

values:
interlanguage-link interwiki-lb
display: none;

values:
interlanguage-link interwiki-lt
display: none;

values:
https://li.wikipedia.org/wiki/Staar
Staar – Limburgish
li
li
interlanguage-link-target

values:
interlanguage-link interwiki-li
display: none;

values:
interlanguage-link interwiki-ln
display: none;

values:
https://jbo.wikipedia.org/wiki/tarci
tarci – Lojban
jbo
jbo
interlanguage-link-target

values:
interlanguage-link interwiki-jbo
display: none;

values:
https://lmo.wikipedia.org/wiki/Stela
Stela – Lombard
lmo
lmo
interlanguage-link-target

values:
interlanguage-link interwiki-lmo
display: none;

values:
https://hu.wikipedia.org/wiki/Csillag
Csillag – Hungarian
hu
hu
interlanguage-link-target

values:
interlanguage-link interwiki-hu
display: none;

values: interlanguage-link interwiki-mk badge-Q17437796 badge-featuredarticle

values:
https://mg.wikipedia.org/wiki/Kintana
Kintana – Malagasy
mg
mg
interlanguage-link-target

values:
interlanguage-link interwiki-mg
display: none;

values: നക്ഷത്രം – Malayalam

values: interlanguage-link interwiki-ml badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-mr
display: none;

values:
interlanguage-link interwiki-xmf
display: none;

values:
interlanguage-link interwiki-arz
display: none;

values:
interlanguage-link interwiki-mzn
display: none;

values:
https://ms.wikipedia.org/wiki/Bintang
Bintang – Malay
ms
ms
interlanguage-link-target

values:
interlanguage-link interwiki-ms
display: none;

values:
interlanguage-link interwiki-cdo
display: none;

values:
https://mwl.wikipedia.org/wiki/Streilha
Streilha – Mirandese
mwl
mwl
interlanguage-link-target

values:
interlanguage-link interwiki-mwl
display: none;

values:
interlanguage-link interwiki-mn
display: none;

values:
interlanguage-link interwiki-my
display: none;

values:
https://nah.wikipedia.org/wiki/Citlalli
Citlalli – Nāhuatl
nah
nah
interlanguage-link-target

values:
interlanguage-link interwiki-nah
display: none;

values:
https://na.wikipedia.org/wiki/Edetang
Edetang – Nauru
interlanguage-link-target

values:
interlanguage-link interwiki-na
display: none;

values:
interlanguage-link interwiki-nl
display: none;

values:
interlanguage-link interwiki-ne
display: none;

values:
interlanguage-link interwiki-new
display: none;

values:
interlanguage-link interwiki-ja
display: none;

values:
https://nap.wikipedia.org/wiki/Stella
Stella – Neapolitan
nap
nap
interlanguage-link-target

values:
interlanguage-link interwiki-nap
display: none;

values:
interlanguage-link interwiki-ce
display: none;

values:
interlanguage-link interwiki-frr
display: none;

values:
https://pih.wikipedia.org/wiki/Sdar
Sdar – Norfuk / Pitkern
pih
pih
interlanguage-link-target

values:
interlanguage-link interwiki-pih
display: none;

values:
https://no.wikipedia.org/wiki/Stjerne
Stjerne – Norwegian
no
no
interlanguage-link-target

values: interlanguage-link interwiki-no badge-Q17437796 badge-featuredarticle

values:
https://nn.wikipedia.org/wiki/Stjerne
Stjerne – Norwegian Nynorsk
nn
nn
interlanguage-link-target

values:
interlanguage-link interwiki-nn
display: none;

values:
interlanguage-link interwiki-nrm
display: none;

values:
https://nov.wikipedia.org/wiki/Stele
Stele – Novial
nov
nov
interlanguage-link-target

values:
interlanguage-link interwiki-nov
display: none;

values:
https://oc.wikipedia.org/wiki/Estela
Estela – Occitan
oc
oc
interlanguage-link-target

values:
interlanguage-link interwiki-oc
display: none;

values:
https://uz.wikipedia.org/wiki/Yulduz
Yulduz – Uzbek
uz
uz
interlanguage-link-target

values: interlanguage-link interwiki-uz badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-pa
display: none;

values:
interlanguage-link interwiki-pnb
display: none;

values:
https://jam.wikipedia.org/wiki/Staar
Staar – Jamaican Creole English
jam
jam
interlanguage-link-target

values:
interlanguage-link interwiki-jam
display: none;

values:
interlanguage-link interwiki-pcd
display: none;

values:
interlanguage-link interwiki-pms
display: none;

values:
interlanguage-link interwiki-nds
display: none;

values:
https://pl.wikipedia.org/wiki/Gwiazda
Gwiazda – Polish
pl
pl
interlanguage-link-target

values:
interlanguage-link interwiki-pl
display: none;

values:
https://pt.wikipedia.org/wiki/Estrela
Estrela – Portuguese
pt
pt
interlanguage-link-target

values:
interlanguage-link interwiki-pt
display: none;

values:
interlanguage-link interwiki-kaa
display: none;

values:
https://ksh.wikipedia.org/wiki/Steern
Steern – Colognian
ksh
ksh
interlanguage-link-target

values:
interlanguage-link interwiki-ksh
display: none;

values:
https://ro.wikipedia.org/wiki/Stea
Stea – Romanian
ro
ro
interlanguage-link-target

values:
interlanguage-link interwiki-ro
display: none;

values:
https://rmy.wikipedia.org/wiki/Chexay
Chexay – Romani
rmy
rmy
interlanguage-link-target

values:
interlanguage-link interwiki-rmy
display: none;

values:
https://qu.wikipedia.org/wiki/Quyllur
Quyllur – Quechua
qu
qu
interlanguage-link-target

values:
interlanguage-link interwiki-qu
display: none;

values: Звізда – Rusyn

values:
interlanguage-link interwiki-rue
display: none;

values: Звезда – Russian

values:
interlanguage-link interwiki-ru
display: none;

values: Сулус – Sakha

values:
interlanguage-link interwiki-sah
display: none;

values:
interlanguage-link interwiki-sa
display: none;

values:
https://sc.wikipedia.org/wiki/Istedda
Istedda – Sardinian
sc
sc
interlanguage-link-target

values:
interlanguage-link interwiki-sc
display: none;

values:
https://sco.wikipedia.org/wiki/Starn
Starn – Scots
sco
sco
interlanguage-link-target

values:
interlanguage-link interwiki-sco
display: none;

values:
https://stq.wikipedia.org/wiki/Stiern
Stiern – Saterland Frisian
stq
stq
interlanguage-link-target

values:
interlanguage-link interwiki-stq
display: none;

values:
https://sq.wikipedia.org/wiki/Ylli
Ylli – Albanian
sq
sq
interlanguage-link-target

values:
interlanguage-link interwiki-sq
display: none;

values:
https://scn.wikipedia.org/wiki/Stidda
Stidda – Sicilian
scn
scn
interlanguage-link-target

values:
interlanguage-link interwiki-scn
display: none;

values:
interlanguage-link interwiki-si
display: none;

values:
https://simple.wikipedia.org/wiki/Star
Star – Simple English
simple
simple
interlanguage-link-target

values:
interlanguage-link interwiki-simple
display: none;

values:
interlanguage-link interwiki-sd
display: none;

values:
https://sk.wikipedia.org/wiki/Hviezda
Hviezda – Slovak
sk
sk
interlanguage-link-target

values: interlanguage-link interwiki-sk badge-Q17437798 badge-goodarticle

values:
https://sl.wikipedia.org/wiki/Zvezda
Zvezda – Slovenian
sl
sl
interlanguage-link-target

values:
interlanguage-link interwiki-sl
display: none;

values:
interlanguage-link interwiki-cu
display: none;

values:
https://szl.wikipedia.org/wiki/Gwjozda
Gwjozda – Silesian
szl
szl
interlanguage-link-target

values:
interlanguage-link interwiki-szl
display: none;

values:
https://so.wikipedia.org/wiki/Xidig
Xidig – Somali
so
so
interlanguage-link-target

values:
interlanguage-link interwiki-so
display: none;

values:
interlanguage-link interwiki-ckb
display: none;

values: Звезда – Serbian

values:
interlanguage-link interwiki-sr
display: none;

values:
https://sh.wikipedia.org/wiki/Zvijezda
Zvijezda – Serbo-Croatian
sh
sh
interlanguage-link-target

values:
interlanguage-link interwiki-sh
display: none;

values:
interlanguage-link interwiki-su
display: none;

values:
interlanguage-link interwiki-fi
display: none;

values: interlanguage-link interwiki-sv badge-Q17437796 badge-featuredarticle

values:
https://tl.wikipedia.org/wiki/Bituin
Bituin – Tagalog
tl
tl
interlanguage-link-target

values:
interlanguage-link interwiki-tl
display: none;

values: விண்மீன் – Tamil

values:
interlanguage-link interwiki-ta
display: none;

values:
https://kab.wikipedia.org/wiki/Itri
Itri – Kabyle
kab
kab
interlanguage-link-target

values:
interlanguage-link interwiki-kab
display: none;

values: Йолдыз – Tatar

values:
interlanguage-link interwiki-tt
display: none;

values: నక్షత్రము (ఖగోళశాస్త్రం) – Telugu

values:
interlanguage-link interwiki-te
display: none;

values: ดาวฤกษ์ – Thai

values: interlanguage-link interwiki-th badge-Q17437796 badge-featuredarticle

values: Ситора – Tajik

values:
interlanguage-link interwiki-tg
display: none;

values:
interlanguage-link interwiki-chr
display: none;

values:
https://chy.wikipedia.org/wiki/Hotohke
Hotohke – Cheyenne
chy
chy
interlanguage-link-target

values:
interlanguage-link interwiki-chy
display: none;

values: interlanguage-link interwiki-tr badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-tk
display: none;

values: Кизили – Udmurt

values:
interlanguage-link interwiki-udm
display: none;

values:
interlanguage-link interwiki-uk
display: none;

values: ستارہ – Urdu

values:
interlanguage-link interwiki-ur
display: none;

values:
interlanguage-link interwiki-vec
display: none;

values:
interlanguage-link interwiki-vep
display: none;

values:
https://vi.wikipedia.org/wiki/Sao
Sao – Vietnamese
vi
vi
interlanguage-link-target

values: interlanguage-link interwiki-vi badge-Q17437796 badge-featuredarticle

values:
interlanguage-link interwiki-fiu-vro
display: none;

values:
https://wa.wikipedia.org/wiki/Sitoele
Sitoele – Walloon
wa
wa
interlanguage-link-target

values:
interlanguage-link interwiki-wa
display: none;

values:
interlanguage-link interwiki-vls
display: none;

values:
https://war.wikipedia.org/wiki/Bitoon
Bitoon – Waray
war
war
interlanguage-link-target

values:
interlanguage-link interwiki-war
display: none;

values:
interlanguage-link interwiki-wuu
display: none;

values:
interlanguage-link interwiki-yi
display: none;

values:
interlanguage-link interwiki-yo
display: none;

values:
interlanguage-link interwiki-zh-yue
display: none;

values:
https://diq.wikipedia.org/wiki/Estare
Estare – Zazaki
diq
diq
interlanguage-link-target

values:
interlanguage-link interwiki-diq
display: none;

values:
interlanguage-link interwiki-bat-smg
display: none;

values:
interlanguage-link interwiki-zh
display: none;

values:
interlanguage-link interwiki-dty
display: none;

values: Седкъа – Ingush

values:
interlanguage-link interwiki-inh
display: none;

values:
interlanguage-link interwiki-kbp
display: none;

values:
https://lfn.wikipedia.org/wiki/Stela
Stela – Lingua Franca Nova
lfn
lfn
interlanguage-link-target

values:
interlanguage-link interwiki-lfn
display: none;

values: All languages (initial selection from common choices by you and others)

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Star rootpage-Star skin-vector action-view