"Reflection nebula In astronomy, reflection nebulae are clouds of interstellar dust which might reflect the light of a nearby star or stars. The energy from the nearby stars is insufficient to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible. Thus, the frequency spectrum shown by reflection nebulae is similar to that of the illuminating stars. Among the microscopic particles responsible for the scattering are carbon compounds (e. g. diamond dust) and compounds of other elements such as iron and nickel. The latter two are often"
"Interstellar cloud An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium, (ISM), the matter and radiation that exists in the space between the star systems in a galaxy. Depending on the density, size, and temperature of a given cloud, its hydrogen can be neutral, making an H I region; ionized, or plasma making it an H II region; or molecular, which are referred to simply as molecular clouds, or sometimetimes dense clouds. Neutral and ionized clouds are sometimes also"
"called ""diffuse clouds"". An interstellar cloud is formed by the gas and dust particles from a red giant in its later life. The chemical composition of interstellar clouds is determined by studying electromagnetic radiation or EM radiation that they emanate, and we receive – from radio waves through visible light, to gamma rays on the electromagnetic spectrum – that we receive from them. Large radio telescopes scan the intensity in the sky of particular frequencies of electromagnetic radiation which are characteristic of certain molecules' spectra. Some interstellar clouds are cold and tend to give out EM radiation of large wavelengths."
"this assumption in observations of some other galaxies. Within molecular clouds are regions with higher density, where lots of dust and gas cores reside, called clumps. These clumps are the beginning of star formation, if gravity can overcome the high density and force the dust and gas to collapse. Within the Milky Way, molecular gas clouds account for less than one percent of the volume of the interstellar medium (ISM), yet it is also the densest part of the medium, comprising roughly half of the total gas mass interior to the Sun's galactic orbit. The bulk of the molecular gas"
"Interplanetary dust cloud The interplanetary dust cloud, or zodiacal cloud, consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. In our Solar System, the interplanetary dust particles have a role in scattering sunlight and in emitting thermal radiation, which is the most prominent feature of the night sky's radiation with wavelengths ranging 5–50 μm. The particle sizes of grains characterizing the infrared emission"
"Intergalactic dust Intergalactic dust is cosmic dust in between galaxies in intergalactic space. Evidence for intergalactic dust has been suggested as early as 1949, and study of it grew throughout the late 20th century. There are large variations in the distribution of intergalactic dust. The dust may affect intergalactic distance measurements, such as to supernova and quasars in other galaxies. Intergalactic dust can form intergalactic dust clouds, known to exist around some galaxies since the 1960s. By the 1980s, at least four intergalactic dust clouds had been discovered within several megaparsec (Mpc) of the Milky Way galaxy, exemplified by the"
"silicates, polycyclic aromatic hydrocarbons, and water ice. The large grains in interstellar space are probably complex, with refractory cores that condensed within stellar outflows topped by layers acquired subsequently during incursions into cold dense interstellar clouds. That cyclic process of growth and destruction outside of the clouds has been modeled to demonstrate that the cores live much longer than the average lifetime of dust mass. Those cores mostly start with silicate particles condensing in the atmospheres of cool oxygen rich red-giant stars and carbon grains condensing in the atmospheres of cool carbon stars. The red-giant stars have evolved off the"
"mostly emitted by dust. Wreath Nebula The Wreath Nebula (also known as Barnard 3 or IRAS Ring G159.6-18.5 is an emission nebula and H II region with a radius of about 22 light-years, located about 1,000 light-years away within our Milky Way galaxy in the Perseus Molecular Cloud complex, near the boundary with the constellation of Taurus. Interstellar clouds like these are stellar nurseries, places where baby stars are being born. The green ring (evergreen) is made of tiny particles of warm dust whose composition is very similar to smog found here on Earth. The red cloud (bow) in the"
"metallicity is needed. High-velocity clouds are identified with an HVC prefix, as with HVC 127-41-330. Interstellar cloud An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium, (ISM), the matter and radiation that exists in the space between the star systems in a galaxy. Depending on the density, size, and temperature of a given cloud, its hydrogen can be neutral, making an H I region; ionized, or plasma making it an H II region; or molecular, which are referred to"
"stars known as globular clusters. Between the stars lies the interstellar medium, a region of sparse matter. In the densest regions, molecular clouds of molecular hydrogen and other elements create star-forming regions. These begin as a compact pre-stellar core or dark nebulae, which concentrate and collapse (in volumes determined by the Jeans length) to form compact protostars. As the more massive stars appear, they transform the cloud into an H II region (ionized atomic hydrogen) of glowing gas and plasma. The stellar wind and supernova explosions from these stars eventually cause the cloud to disperse, often leaving behind one or"
"Interstellar ice Interstellar ice consists of grains of volatiles in the ice phase that form in the interstellar medium. Ice and dust grains form the primary material out of which the Solar System was formed. Grains of ice are found in the dense regions of molecular clouds, where new stars are formed. Temperatures in these regions can be as low as , allowing molecules that collide with grains to form an icy mantle. Thereafter, atoms undergo thermal motion across the surface, eventually forming bonds with other atoms. This results in the formation of water and methanol. Indeed, the ices are"
"structure on all spatial scales. Stars are born deep inside large complexes of molecular clouds, typically a few parsecs in size. During their lives and deaths, stars interact physically with the ISM. Stellar winds from young clusters of stars (often with giant or supergiant HII regions surrounding them) and shock waves created by supernovae inject enormous amounts of energy into their surroundings, which leads to hypersonic turbulence. The resultant structures are stellar wind bubbles and superbubbles of hot gas. The Sun is currently traveling through the Local Interstellar Cloud, a denser region in the low-density Local Bubble. To measure the"
"partially understood. Astronomers know that the dust is formed in the envelopes of late-evolved stars from specific observational signatures. In infrared light, emission at 9.7 micrometres is a signature of silicate dust in cool evolved oxygen-rich giant stars. Emission at 11.5 micrometres indicates the presence of silicon carbide dust in cool evolved carbon-rich giant stars. These help provide evidence that the small silicate particles in space came from the ejected outer envelopes of these stars. Conditions in interstellar space are generally not suitable for the formation of silicate cores. This would take excessive time to accomplish, even if it might"
"star-forming region 26000 light-years from Earth, and around a protostellar binary star, ""IRAS 16293-2422"", 400 light years from Earth. Observation of in-falling glycolaldehyde spectra 60 AU from ""IRAS 16293-2422"" suggests that complex organic molecules may form in stellar systems prior to the formation of planets, eventually arriving on young planets early in their formation. The interior region of a dust cloud is known to be relatively cold. With temperatures as cold as 4 Kelvin the gases within the cloud will freeze and fasten themselves to the dust, which provides the reaction conditions conducive for the formation of complex molecules such"
"into infrared wavelengths than the Hubble can. Dust disks have now been found around more than 15% of nearby sunlike stars. The dust is thought to be generated by collisions among comets and asteroids. Radiation pressure from the star will push the dust particles away into interstellar space over a relatively short timescale. Therefore, the detection of dust indicates continual replenishment by new collisions, and provides strong indirect evidence of the presence of small bodies like comets and asteroids that orbit the parent star. For example, the dust disk around the star tau Ceti indicates that that star has a"
"In an article published in 1947, he and Edith Reilly hypothesized that these clouds were ""similar to insect's cocoons"" that were undergoing gravitational collapse to form new stars, from which stars and star clusters were born. This hypothesis was difficult to verify due to the observational difficulties of establishing what was happening inside a dense dark cloud that obscured all visible light emitted from within it. An analysis of near-infrared observations published in 1990 confirmed that stars were being born inside Bok globules. Further observations have revealed that some Bok globules contain embedded warm sources, some contain Herbig–Haro objects, and"
"surfaces where life then emerged (abiogenesis). From the early 1970s, it started to become evident that interstellar dust included a large component of organic molecules. Interstellar molecules are formed by chemical reactions within very sparse interstellar or circumstellar clouds of dust and gas. The dust plays a critical role in shielding the molecules from the ionizing effect of ultraviolet radiation emitted by stars. The chemistry leading to life may have begun shortly after the Big Bang, 13.8 billion years ago, during a habitable epoch when the Universe was only 10 to 17 million years old. Though the presence of life"
"the shadows of evaporating gaseous globules (EGGs), which shield the gas behind them from intense UV flux. EGGs are themselves incubators of new stars. The stars then emerge from the EGGs, which then are evaporated. Images taken with the Spitzer Space Telescope uncovered a cloud of hot dust in the vicinity of the Pillars of Creation that Nicolas Flagey accounted to be a shock wave produced by a supernova. The appearance of the cloud suggests the supernova shockwave would have destroyed the Pillars of Creation 6,000 years ago. Given the distance of roughly 7,000 light years to the Pillars of"
"dust and gas not only feed material onto the growing new stars, but can be the raw material for new planetary systems. RCW 49 RCW 49 is a H II region nebula located 13,700 light years away. It is a dusty stellar nursery that contains more than 2,200 stars and is about 350 light years across. The nebula RCW49, shown in infrared light in this image from the Spitzer Space Telescope, is a nursery for newborn stars. Using NASA's Spitzer Space Telescope, astronomers have found in RCW49 more than 300 newborn or 'protostars,' all with circumstellar disks of dust and"
"stars in the star cluster are two stars with late-O or early-B spectral types, but the cluster also contains hundreds of lower-mass stars. This region is also home to objects with Herbig–Haro jets, HH 1042 and HH 1043. Like most star-forming regions, the interstellar medium around RCW 36 contains both the gas from which stars form and some newly formed young stars. Here, young stellar clusters form in giant molecular clouds. Molecular clouds are the coldest, densest form of interstellar gas and are composed mostly of molecular hydrogen (H), but also include more complex molecules, cosmic dust, and atomic helium."
"Stellar birthline The stellar birthline is a predicted line on the Hertzsprung–Russell diagram that relates the effective temperature and luminosity of pre-main-sequence stars at the start of their contraction. Prior to this point, the objects are accreting protostars, and are so deeply embedded in the cloud of dust and gas from which they are forming that they radiate only in far infrared and millimeter wavelengths. Once stellar winds disperse this cloud, the star becomes visible as a pre-main-sequence object. The set of locations on the Hertzsprung–Russell diagram where these newly visible stars reside is called the ""birthline"", and is found"
"found within these lanes, mix together and combine to form stars and planets. Dust lane A dust lane is a relatively dense obscuring band of interstellar dust, observed as a dark swath against the background of a brighter object, especially a galaxy. These dust lanes can usually be seen in spiral galaxies (e.g., the Milky Way) when viewed from the edge. Due to the dense and relatively thick nature of this dust, light from the galaxy is reduced by several magnitudes. In the Milky Way, this reduction of light makes it impossible to see the light from the central bulge"
"Cosmic dust Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles are between a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust (such as in the zodiacal cloud) and circumplanetary dust (such as in a planetary ring). In the Solar System, interplanetary dust causes the zodiacal light. Solar System dust includes comet dust, asteroidal dust, dust from the Kuiper belt, and interstellar dust passing through the Solar System. Thousands"
"cavern – are composed of interstellar hydrogen gas and dust, which act as incubators for new stars. Inside the columns and on their surface astronomers have found knots or globules of denser gas, called EGGs (""Evaporating Gaseous Globules""). Stars are being formed inside some of these EGGs. X-ray images from the Chandra observatory compared with Hubble's ""Pillars"" image have shown that X-ray sources (from young stars) do not coincide with the pillars, but instead randomly dot the area. Any protostars in the pillars' EGGs are not yet hot enough to emit X-rays. Evidence from the Spitzer Telescope suggested that the"
"Coreshine Coreshine is an astronomical term for infrared light scattered by unusually large grains of dust in the denser core regions of molecular clouds and which evidently begin their growth before the start of cloud collapse. These clouds which are opaque to visible light, are a mixture of gas and dust and are the regions where stars are formed. Coreshine offers a new tool for observing the earliest phases of star formation, a process effectively hidden up to now. The scattered mid-infrared light, found throughout our galaxy, could reveal the origins of the cloud material, the size and density of"
"regions are several times that distance from Earth. Secondly, the formation of these stars is deeply obscured by dust, and visible light observations are impossible. Radio and infrared light can penetrate the dust, but the youngest stars may not emit much light at these wavelengths. H II region An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically a cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about"
"Comet dust Comet dust refers to cosmic dust that originates from a comet. Comet dust can provide clues to comets' origin. When the Earth passes through a comet dust trail, it can produce a meteor shower. The models for the origin of comets are: Bulk properties of the comet dust such as density as well as the chemical composition can distinguish between the models. For example, the isotopic ratios of comet and of interstellar dust are very similar, indicating a common origin. The 1) interstellar model says that ices formed on dust grains in the dense cloud that preceded the"
"in 2018. Coreshine Coreshine is an astronomical term for infrared light scattered by unusually large grains of dust in the denser core regions of molecular clouds and which evidently begin their growth before the start of cloud collapse. These clouds which are opaque to visible light, are a mixture of gas and dust and are the regions where stars are formed. Coreshine offers a new tool for observing the earliest phases of star formation, a process effectively hidden up to now. The scattered mid-infrared light, found throughout our galaxy, could reveal the origins of the cloud material, the size and"
"Okroy cloud. In February 2014, NASA announced a greatly upgraded database for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe. According to scientists, more than 20% of the carbon in the universe may be associated with PAHs, possible starting materials for the formation of life. PAHs seem to have been formed as early as two billion years after the big bang, are widespread throughout the universe, and are associated with new stars and exoplanets. Intergalactic dust Intergalactic dust is cosmic dust in between galaxies in intergalactic space. Evidence for intergalactic dust has been suggested as early as 1949, and study"
"Nebula A nebula (Latin for ""cloud"" or ""fog""; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, the term was used to describe any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was once referred to as the ""Andromeda Nebula"" (and spiral galaxies in general as ""spiral nebulae"") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others. Most nebulae are of vast size; some are hundreds of light years in diameter. A nebula that"
"found, and conversely, a compositional analysis of a dust particle can reveal much about the dust particle's origin. General diffuse interstellar medium dust, dust grains in dense clouds, planetary rings dust, and circumstellar dust, are each different in their characteristics. For example, grains in dense clouds have acquired a mantle of ice and on average are larger than dust particles in the diffuse interstellar medium. ""Interplanetary dust particles"" (IDPs) are generally larger still. Most of the influx of extraterrestrial matter that falls onto the Earth is dominated by meteoroids with diameters in the range 50 to 500 micrometers, of average"
"instead of simply from a small local region. Another theory of massive star formation suggests that massive stars may form by the coalescence of two or more stars of lower mass. Star formation Star formation is the process by which dense regions within molecular clouds in The ""medium"" is present further soon.-->interstellar space, sometimes referred to as ""stellar nurseries"" or ""star-forming regions"", collapse and form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young"
"""Pioneer 10"", ""Pioneer 11"", ""Ulysses"" (heliocentric orbit out to the distance of Jupiter), ""Galileo"" (Jupiter Orbiter), ""Cassini"" (Saturn orbiter), and ""New Horizons"" (see Venetia Burney Student Dust Counter). Interplanetary dust cloud The interplanetary dust cloud, or zodiacal cloud, consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. In our Solar System, the interplanetary dust particles have a role in scattering sunlight and in"