5:03 PM 12/26/2018 5:03 PM 12/26/2018 Betelgeuse Web Images News Blogs Scholar α Ori, 58 Ori, HD 39801, SAO 113271, HR 2061 Betelgeuse (Alpha (α) Orionis) is a semiregular variable star located 427 light-years away (*). It is the second brightest star in the constellation Orion, and the tenth brightest star in the night sky. Although it has the Bayer designation "alpha", it is not as bright as Rigel (Beta Orionis). It is a vertex of the Winter Triangle asterism.Betelgeuse is a red supergiant, one of the physically largest stars known. If it were placed at the center of our solar system, its outer surface would possibly extend to the orbit of Mars. As it is, Betelgeuse is so large and so close that it is the star with the third largest angular diameter as viewed from Earth (*), smaller only than the Sun and R Doradus, and one of only a dozen or so stars that telescopes have imaged as a visible disk (See photo, at right and a picture of hotspots on Betelgeuse.) The angular diameter of Betelgeuse was first measured in 1920-1921 by Michelson and Pease using an astronomical interferometer on the Mount Wilson 100 inch telescope. Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Betelgeuse available from SIMBAD Location RA: 5h55m10.3s DEC: +7°24m25.0s Distance Spectral Type 650 light-years e Bellatrix Web Images News Blogs Scholar γ Ori, 24 Ori, HD 35468, SAO 112740, HR 1790 Gamma Orionis (γ Ori / γ Orionis / Bellatrix) is the third brightest star in the constellation Orion and the twenty-seventh brightest star in the nighttime sky. The name Bellatrix is Latin for Amazon. It is also known as the Amazon Star, the warrioress, or Gamma Orionis. It was once thought to belong to the physical association of stars that comprise much of the constellation of Orion. But this is no longer believed to be the case, as Gamma Orionis is much closer to us than the group.Historically this star was used as a luminosity standard that astronomers could compare with other stars to check for variability. But it was later discovered that Bellatrix itself is an eruptive variable, changing in luminosity by a few percent over time. It ranges in magnitude from 1.59 to 1.64.It is approximately 500 light years from earth. Source: http://www.astro.wisc.edu/~dolan/constellations/hr/1790.html Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Bellatrix available from SIMBAD Location RA: 5h25m7.9s DEC: +6°20m59.0s Distance Spectral Type 110 light-years B2III Alnitak Web Images News Blogs Scholar ζ Ori, 50 Ori, HD 37742, SAO 132444, HR 1948 Zeta Orionis is a star in the constellation Orion. It also has the traditional name Alnitak. The name is taken from the Arabic an-nitaq, “the belt”. Alnitak is a triple star system at the eastern end of Orion's belt. The primary is a blue supergiant that is also a close binary. The Alnitak system is bathed in the nebulosity of IC 434. Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Alnitak available from SIMBAD Location RA: 5h40m45.5s DEC: -1°56m34.0s Distance Spectral Type 140 light-years e Alnilam Web Images News Blogs Scholar ε Ori, 46 Ori, HD 37128, SAO 132346, HR 1903 Epsilon Orionis (ε Ori / ε Orionis) is a large blue star in the constellation of Orion. It also has the traditional name Alnilam. Its Flamsteed designation is 46 Orionis.It is the 30th brightest star in the sky (the 4th brightest in Orion) and as a blue-white supergiant it is one of the most luminious stars known. It is the middle star of Orion's belt.It is also one of the 57 stars used in celestial navigation. For middle latitudes, it is at its highest point in the sky around 10 p.m. on December 10.Alnilam's relatively simple spectrum has made it useful for studying the interstellar medium. Within the next million years, this star may turn into a red supergiant and explode as a supernova. It is surrounded by a molecular cloud, NGC 1990, which it brightens to make a reflection nebula. Its stellar winds may reach up to 2000 km/s, causing it to lose mass about 20 million times more rapidly than the Sun. Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Alnilam available from SIMBAD Location RA: 5h36m12.8s DEC: -1°12m7.0s Spectral Type e Mintaka Web Images News Blogs Scholar δ Ori, 34 Ori, HD 36486, SAO 132220, HR 1852 Delta Orionis (δ Ori) is one of the three stars of the belt of the constellation Orion. It also has the traditional name Mintaka (from منطقة manţaqah, which means "belt" in Arabic). Mintaka is actually a multiple star with a magnitude 7 star about 52" away from the main component and an even fainter star in between. The main component itself is also double, consisting of a class B giant and a smaller but hotter class O. The stars orbit each other every 5.73 days. These two stars are both about 70,000 times as luminous as the Sun with a mass of some 20 solar masses.In 1904, Johannes Hartmann discovered that interstellar space contains a thin gas, by using Mintaka as a background source (see interstellar medium). Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Mintaka available from SIMBAD Location RA: 5h32m0.4s DEC: -0°17m57.0s Distance Spectral Type 230 light-years O9.5II Rigel Web Images News Blogs Scholar β Ori, 19 Ori, HD 34085, SAO 131907, HR 1713 Rigel (pronounced ) (β Orionis) is the brightest star in the constellation Orion and the seventh brightest star in the sky, with visual magnitude 0.12. Although it has the Bayer designation "beta", it is almost always brighter than Alpha Orionis (Betelgeuse). It also has the alternative traditional names Algebar or Elgebar, but these are almost never used.The star's name comes from its location at the "left foot" of Orion. It is a contraction of "Rijl Jauza al-Yusra", this being Arabic for "left foot of the Central One". Another Arabic name is الرجل الجبار ar-rijl al-jabbār, "the foot of the great one" (giant, conqueror, etc.), which is also the source of the variant name Algebar.The distance to Rigel from our star system is somewhere between 700 and 900 light years; Hipparcos' best guess is 773 light years (237 parsecs), but that far out the range of error is quite large. Rigel is a B8 Ia supergiant, and shines with approximately 40,000 times the luminosity of the Sun. It is far and away the most luminous star in our local region of the Milky Way; the nearest more powerful star is Deneb, as much as 3300 light years (1000 parsecs) down the Orion Arm.As it is so bright, and is moving through a region of nebulosity, it should come as no surprise to learn that Rigel lights up several dust clouds in its general vicinity. The most notable is the Witch Head Nebula. Rigel is also associated with the Orion Nebula, which—while more or less along the same line of sight as the star—is about twice as far away from Earth. Despite the difference in distance, projecting Rigel's path through space for its expected age brings it close to the nebula. As a result, Rigel is sometimes classified as an outlying member of the Orion OB1 Association, along with many of the other bright stars in that region of the sky; more commonly it is considered a member of the Taurus-Orion R1 Association, and the OB1 association is reserved for stars closer to the nebula and more recently formed.Rigel is a triple star. The main star is orbited by a binary system, Rigel B and C, which orbit one another closely at 28 AU and in turn orbit around Rigel as a unit, at a distance of about 2000 AU. The stars are similar, both belonging to the spectral class B9V. Rigel B is more massive, with a mass 2.5 times solar versus 1.9 solar mass of Rigel C. They orbit Rigel A at the distance of 28 AU.It is also variable, in a slight, irregular way common to supergiants. The range of variability is from 0.03 to 0.3 of a magnitude, over an average of 25 days. A fourth star in the system is sometimes proposed, but it is generally considered that this is a misinterpretation of the main star's variability, which may be caused by physical pulsation of the surface. Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Rigel available from SIMBAD Location RA: 5h14m32.3s DEC: -8°12m6.0s Distance Spectral Type 250 light-years e κ Ori Web Images News Blogs Scholar 53 Ori, HD 38771, SAO 132542, HR 2004 Kappa Orionis (κ Ori / κ Orionis / 53 Orionis) is the sixth-brightest star in the constellation of Orion. It also has the traditional name Saiph. The name is from the Arabic saif al jabbar, sword of the giant. Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on κ Ori available from SIMBAD Location RA: 5h47m45.4s DEC: -9°40m11.0s Distance Spectral Type 220 light-years v Capella Web Images News Blogs Scholar α Aur, 13 Aur, HD 34029, SAO 40186, HR 1708 Capella (α Aur / α Aurigae / Alpha Aurigae) is the brightest star in the constellation Auriga and sixth brightest star in the sky. Although it appears as a single point to the naked eye, Capella is actually a bright close binary pair of stars along side a second, fainter binary. Full Article Text available from Wikipedia under the terms of the GNU Free Documentation License More technical information on Capella available from SIMBAD Location RA: 5h16m41.4s DEC: +45°59m53.0s Distance Spectral Type 45 light-years v 5:14 PM 12/26/2018 5:15 PM 12/26/2018