"by Gustav Holst. This table provides a non-exhaustive list of angular measurements conducted since 1920. Also included is a column providing a current range of radii for each study based on Betelgeuse's most recent distance estimate (Harper ""et al."") of 197 ± 45 pc. Betelgeuse Betelgeuse, also designated Alpha Orionis (α Orionis, abbreviated Alpha Ori, α Ori), is on average the ninth-brightest star in the night sky and second-brightest in the constellation of Orion. It is distinctly reddish, and is a semiregular variable star whose apparent magnitude varies between 0.0 and 1.3, the widest range of any first-magnitude star. Betelgeuse"
"Saiph Saiph, also designated Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's main quadrangle, it is the star at the south-eastern corner. A northern-hemisphere observer facing south would see it at the lower left of Orion, and a southern-hemisphere observer facing north would see it at the upper right. Parallax measurements yield an estimated distance of 650 light-years (198 parsecs) from the Sun, which is about the same as Betelgeuse. It is smaller, less luminous but hotter"
"Chi2 Orionis Chi Orionis (Chi Ori / χ Orionis / χ Ori) is a B-type supergiant star in the constellation of Orion. It has an apparent visual magnitude of 4.63 but being quite distant, and heavily extinguished it burns with the greatest absolute visual light magnitude among stars in Orion within the near reaches of the galaxy, 0.9 of a magnitude greater than Rigel. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. In apparent brightness it ranks, within Orion, admitting the higher published mean brightness of"
"Castor (star) Castor, also designated Alpha Geminorum (α Geminorum, abbreviated Alpha Gem, α Gem) is the second-brightest point of light in the constellation of Gemini and one of the brightest in the night sky. It appears singular to the naked eye, but it is actually a sextuple star system in three binary pairs made up of the stars Castor Aa, Castor Ab, Castor Ba, Castor Bb, Castor Ca, and Castor Cb. Although it has the Bayer designation ""alpha"", it is fainter than Beta Geminorum, Pollux. Castor was recorded as a double star in 1718 by James Pound. It may have"
"YY Geminorum. Castor (star) Castor, also designated Alpha Geminorum (α Geminorum, abbreviated Alpha Gem, α Gem) is the second-brightest point of light in the constellation of Gemini and one of the brightest in the night sky. It appears singular to the naked eye, but it is actually a sextuple star system in three binary pairs made up of the stars Castor Aa, Castor Ab, Castor Ba, Castor Bb, Castor Ca, and Castor Cb. Although it has the Bayer designation ""alpha"", it is fainter than Beta Geminorum, Pollux. Castor was recorded as a double star in 1718 by James Pound. It"
"Canopus Canopus (), also designated Alpha Carinae (α Carinae, abbreviated Alpha Car, α Car), is the brightest star in the southern constellation of Carina, and the second-brightest star in the night sky, after Sirius. Canopus's visual magnitude is −0.74, and it has an absolute magnitude of −5.71. Canopus is a bright giant of spectral type A9, so it is essentially white when seen with the naked eye. It is located in the far southern sky, at a year 2000 declination of and a right ascension of . Its name is generally considered to originate from the mythological Canopus, who was"
"B and C. Bizarrely, θ Orionis C has a second entry in the Washington Double Star Catalog under the name S490. The companion is 10th magnitude and actually lies between θ Ori B and V1073 Ori. θ Orionis, the well known Trapezium cluster, is only 2 arc minutes away from θ Orionis A. Despite the names, θ Orionis A is marginally brighter than the brightest star in the Trapezium. The Catalog of Components of Double and Multiple Stars includes the stars of θ and θ Ori within the same system of 13 components. There are dozens of much fainter stars"
"Omicron2 Orionis Omicron Orionis (ο Ori) is a solitary star in the constellation Orion. It has an apparent visual magnitude of 4.06, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 17.54 mas, it is around 186 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an interstellar absorption factor of 0.09 due to intervening dust. This is a red clump giant star with a stellar classification of K2 IIIb. It is around 5.4 billion years old with a projected rotational velocity that"
"28 times that of the Sun (from an original mass 31.8 times that of the Sun) and an age of 6.2 million years. Large stars such as Saiph (and many other stars in Orion) are destined to collapse on themselves and explode as supernovae. The Wardaman people of northern Australia regard Saiph as the Guman digging stick, used to make a canyon by Black-headed Python. Saiph Saiph, also designated Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's"
"of its proximity to the Solar System. In contrast, the other bright stars of the constellation are stars of great distance and high luminosity. At magnitude 1.5, Epsilon Canis Majoris (Adhara) is the second-brightest star of the constellation and the brightest source of extreme ultraviolet radiation in the night sky. Next in brightness are the yellow-white supergiant Delta (Wezen) at 1.8, the blue-white giant Beta (Mirzam) at 2.0, blue-white supergiants Eta (Aludra) at 2.4 and Omicron at 3.0, and white spectroscopic binary Zeta (Furud), also at 3.0. The red hypergiant VY Canis Majoris is one of the largest stars known,"
"Iota Orionis Iota Orionis (ι Orionis, abbreviated Iota Ori, ι Ori) is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly from the Sun. The system has three components designated Iota Orionis A, B and C. Iota Orionis A is itself a massive spectroscopic binary, with components Iota Orionis Aa"
"fainter Iota Orionis C is an A0 star at 49"". NGC 1980 contains few bright stars other than Iota Orionis. Only eighteen other stars are considered members in a survey down to 14th magnitude, most of them around 9th magnitude but including the 5th magnitude stars HR 1886 and 1887. Iota Orionis Iota Orionis (ι Orionis, abbreviated Iota Ori, ι Ori) is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword."
"disk. At least four of the fifteen stars visible to the unaided eye are orange giants of spectral class K. The second brightest star in the constellation—at apparent magnitude 4.1—is Zeta Telescopii, an orange subgiant of spectral type K1III-IV. Around 1.53 times as massive as the Sun, it shines with 512 times its luminosity. Located 127 light years away from Earth, it has been described as yellow or reddish in appearance. Epsilon Telescopii is a binary star system: the brighter component, Epsilon Telescopii A, is an orange giant of spectral type K0III with an apparent magnitude of +4.52, while the"
"that is the second brightest star in the night sky at magnitude −0.72, 313 light-years from Earth. Alpha Carinae, as Canopus is formally designated, is a variable star that varies by approximately 0.1 magnitudes. Its traditional name comes from the mythological Canopus, who was a navigator for Menelaus, king of Sparta. There are several other stars above magnitude 3 in Carina. Beta Carinae, traditionally called Miaplacidus, is a blue-white hued star of magnitude 1.7, 111 light-years from Earth. Epsilon Carinae is an orange-hued giant star similarly bright to Miaplacidus at magnitude 1.9; it is 630 light-years from Earth. Another fairly"
"Beta Carinae Beta Carinae (β Carinae, abbreviated Beta Car, β Car), also named Miaplacidus, is the second brightest star in the constellation of Carina and one of the brightest stars in the night sky, with apparent magnitude 1.68. It is the brightest star in the south polar asterism known as the Diamond Cross, marking the southwestern end of the asterism. It lies near the planetary nebula IC 2448. Parallax measurements place it at a distance of from the Sun. ""β Carinae"" (Latinised to ""Beta Carinae"") is the star's Bayer designation. The star's historical name ""Miaplacidus"" made its debut on star"
"(not shown on the main map as it is located below the map's southeastern corner, north is up). Instead, the brightest star is Epsilon Sagittarii (ε Sgr) (""Kaus Australis,"" or ""southern part of the bow""), at magnitude 1.85. Sigma Sagittarii (σ Sgr) (""Nunki"") is the constellation's second-brightest star at magnitude 2.08. Nunki is a B2V star approximately 260 light years away. ""Nunki"" is a Babylonian name of uncertain origin, but thought to represent the sacred Babylonian city of Eridu on the Euphrates, which would make Nunki the oldest star name currently in use. Zeta Sagittarii (ζ Sgr) (""Ascella""), with apparent"
"(so named by John Herschel), which should not be confused with the better known Hourglass Nebula (see above). Reflection nebula in the constellation Orion, cataloged as M78 (see graphic). M78 is the brightest of a group of diffuse reflection nebulae that belong to the Orion Molecular Cloud Complex and is about 1,600 light years distant from the Earth. M78 is easily found in small telescopes as a hazy patch and involves two stars of 10th magnitude. These two stars, HD 38563A and HD 38563B, are responsible for making the cloud of dust in M78 visible by reflecting their light. About"
"from Earth. At magnitude 4.4, Beta Leonis Minoris is the second-brightest star and the only one in the constellation with a Bayer designation. It is a binary star, the brighter component of which is an orange giant and the fainter a yellow-white main sequence star. The third-brightest star is 21 Leonis Minoris, a rapidly rotating white main-sequence star of average magnitude 4.5. The constellation also includes two stars with planetary systems, two pairs of interacting galaxies, and the unique deep-sky object Hanny's Voorwerp. The classical astronomers Aratus and Ptolemy had noted the region of what is now Leo Minor to"
"Orion Nebula The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light years across. It has a mass of about 2,000 times that of the Sun. Older texts frequently refer to the Orion Nebula"
"Sigma Sagittarii Sigma Sagittarii (σ Sagittarii, abbreviated Sigma Sgr, σ Sgr), also named Nunki, is the second-brightest star in the constellation of Sagittarius. It has an apparent magnitude of +2.05, making it readily visible to the naked eye. The distance to this star, determined using parallax measurements from the Hipparcos astrometry satellite, yields an estimated value of from the Sun. Sigma Sagittarii has a spectrum matching a stellar classification of B2.5 V, which indicates this is a B-type main-sequence star. Its total luminosity is 3300 times that of the Sun while it has a surface temperature of 18,890 K. X-ray"
"Theta2 Orionis Theta Orionis (θ Ori) is a multiple star system in the constellation Orion. It is a few arc minutes from its more famous neighbour the Trapezium Cluster, also known as θ Orionis. θ Orionis consists of three stars in a line, each about an arc-minute from the next. In addition to the well-known three stars, the Washington Double Star Catalog confusingly lists a component D which is actually θ Orionis C. There is one other star brighter than 10th magnitude in the region. V1073 Orionis is a B9.5 Orion variable that forms an equilateral triangle with θ Ori"
"remain in use, likely because of their proximity to the north celestial pole. Within the constellation's borders, there are 39 stars brighter than or equal to apparent magnitude 6.5. Marking the Little Bear's tail, Polaris, or Alpha Ursae Minoris, is the brightest star in the constellation, varying between apparent magnitude 1.97 and 2.00 over a period of 3.97 days. Located around 432 light-years away from Earth, it is a yellow-white supergiant that varies between spectral types F7Ib and F8Ib, and has around 6 times the Sun's mass, 2,500 times its luminosity and 45 times its radius. Polaris is the brightest"
"Beta Pictoris system is forming an Oort cloud. Numerical modeling of dust ejection indicates radiation pressure may also be responsible and suggests that planets further than about 1 AU from the star cannot directly cause the dust stream. \right)</math></ref> Beta Pictoris Beta Pictoris (β Pic, β Pictoris) is the second brightest star in the constellation Pictor. It is located 63.4 light years from the Solar System, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris system is very young, only 20 to 26 million years old, although it is already in the"
"Sigma Orionis Sigma Orionis or Sigma Ori (σ Orionis, σ Ori) is a multiple star system in the constellation Orion, consisting of the brightest members of a young open cluster. It is found at the eastern end of the belt, south west of Alnitak and west of the Horsehead Nebula which it partially illuminates. The total brightness of the component stars is magnitude 3.80. σ Orionis is a naked eye star at the eastern end of Orion's Belt, and has been known since antiquity, but it was not included in Ptolemy's Almagest. It was referred to by Al Sufi, but"
"Sirius Sirius (, a latinisation of Greek , ""Seirios"", .""glowing"" or ""scorching"") is a binary star and the brightest point of light in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The system has the Bayer designation α (Alpha) Canis Majoris. The binary system consists of a main-sequence star of spectral type A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, designated Sirius B. The distance between the two varies between 8.2 and 31.5 astronomical units as they orbit"
"Pi3 Orionis Pi³ Orionis (π³ Orionis, abbreviated Pi³ Ori, π³ Ori), also named Tabit, is a star in the equatorial constellation of Orion. At an apparent visual magnitude of 3.16, it is readily visible to the naked eye and is the brightest star in the lion's hide (or shield) that Orion is holding. As measured using the parallax technique, it is distant from the Sun. ""π³ Orionis"" (Latinised to ""Pi³ Orionis"") is the system's Bayer designation. It bore the traditional name of ""Tabit"". In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper"
"the White Tiger. Alnilam Alnilam, designated Epsilon Orionis (ε Orionis, abbreviated Epsilon Ori, ε Ori) and 46 Orionis (46 Ori), is a large blue supergiant star some 2,000 light-years distant in the constellation of Orion. It is estimated to be 275,000 to 832,000 times as luminous as the Sun, and 30-64.5 times as massive. It is the 29th-brightest star in the sky (the 4th-brightest in Orion) and is a blue-white supergiant. Together with Mintaka and Alnitak, the three stars make up the belt of Orion, known by many names across many ancient cultures. Alnilam is the middle star. It is"
"HD 36960 HD 36960 (HR 1887) is a B-type main-sequence star in the constellation Orion. At an apparent magnitude of +4.78 it is easily visible to the naked eye in many areas, though in most urban areas it cannot be seen due to light pollution. Although it does not have a Bayer or Flamsteed designation, it is brighter than over 30 Flamsteed stars in Orion]], as well as being brighter than any of the stars in the nearby Orion Nebula such as θ Orionis C and θ Orionis. HD 36960 forms a close pair with the slightly fainter HD 36959"
"Aldebaran Aldebaran, designated Alpha Tauri (α Tauri, abbreviated Alpha Tau, α Tau), is an orange giant star located about 65 light-years from the Sun in the zodiac constellation Taurus. It is the brightest star in its constellation and usually the fourteenth-brightest star in the night sky, though it varies slowly in brightness between magnitude 0.75 and 0.95. Aldebaran hosts a planet several times the size of Jupiter￼, named Aldebaran b. The planetary exploration probe Pioneer 10 is currently heading in the general direction of the star and should make its closest approach in about two million years. ""Alpha Tauri"" is"
"Omega Orionis Omega Orionis (ω Ori) is a star in the constellation Orion. Its apparent magnitude is 4.57 and is located approximately 1,400 light years from our solar system. It is surrounded by a cloud of dust, forming a modest reflection nebula over a light-year wide. Omega Orionis is a B-type main sequence star of spectral type B3 Ve with an effective temperature of 19,000 K. Including a large amount of ultraviolet radiation, Omega Orionis shines with a Luminosity 6,031 times greater than the Sun's and it has a radius 5.9 times larger than solar radius, The projected rotation speed"
"barium, which may be the result of the S-process of nucleosynthesis in the outer atmosphere of the star. It has a relatively high peculiar velocity of . \end{align}</math></ref> Epsilon Pegasi Epsilon Pegasi (ε Pegasi, abbreviated Epsilon Peg, ε Peg), also named Enif (EE-nif), is the brightest star in the northern constellation of Pegasus. With an apparent visual magnitude of 2.4, this is a second-magnitude star that is readily visible to the naked eye. The distance to this star can be estimated using parallax measurements from the Hipparcos astrometry satellite, yielding a value of around . ""ε Pegasi"" (Latinised to ""Epsilon"
"O stars should commonly produce bow waves if this model is correct. Sigma Orionis Sigma Orionis or Sigma Ori (σ Orionis, σ Ori) is a multiple star system in the constellation Orion, consisting of the brightest members of a young open cluster. It is found at the eastern end of the belt, south west of Alnitak and west of the Horsehead Nebula which it partially illuminates. The total brightness of the component stars is magnitude 3.80. σ Orionis is a naked eye star at the eastern end of Orion's Belt, and has been known since antiquity, but it was not"
"of names approved by the WGSN; which included ""Arcturus"" for this star. It is now so entered in the IAU Catalog of Star Names. With an apparent visual magnitude of −0.05, Arcturus is the brightest star in the northern celestial hemisphere and the fourth-brightest star in the night sky, after Sirius (−1.46 apparent magnitude), Canopus (−0.72) and Alpha Centauri AB (−0.27). However, Alpha Centauri AB is a binary star, whose unresolved components to the naked eye are both fainter than Arcturus. This makes Arcturus the third-brightest individual star, just ahead of Alpha Centauri A, whose apparent magnitude is −0.01. The"