Auriga, the Charioteer, is a constellation that is easily distinguished as an elongated pentagram made up of bright stars. It rises early in the late fall and passes high overhead for northern hemisphere observers. Auriga and Taurus herald the coming of the other bright winter constellations Orion, Gemini and Canis Major. Hold your mouse cursor over the image to see constellation figures, boundaries, and star identifications. Auriga is dominated by Capella, Alpha Aurigae, the sixth brightest star in the night sky at magnitude 0.08. Capella is also called the "Goat Star", "She-Goat", or "Nanny Goat" depending on the tradition and translation. Capella is a spectral-type G spectroscopic binary comprised of two yellow-giant stars and two red dwarfs. This multiple-star system is located 42 light-years away from the Earth. Next to Capella are the "Kids", a small triangular grouping of stars. The Kids are comprised of Epsilon Aurigae, the closest star to Capella in the triangle, and Eta and Zeta Aurigae. Epsilon is actually one of the most luminous stars in the entire galaxy, but because it is 2,000 light-years away, it only shines with an apparent visual magnitude of 3.0. Epsilon and Zeta are both eclipsing binary stars. Beta Aurigae is Menkalinan, a triple-star comprised of two spectral-type A sub-giant stars that are an eclipsing binary, and a third red dwarf star. Menkalinan varies in magnitude from 1.89 to 1.98 and is located 85 light-years away. Theta Aurigae is Mahasim, sometimes also called Bogardus. Mehasim is a double star with a spectral-type A magnitude 2.7 white dwarf primary and a spectral-type G yellow main sequence dwarf star that shines at magnitude 7.2. The system is located 173 light-years away. The corner star at lower right in the pentagram in the image is Elnath, Beta Tauri, shining at magnitude 1.68. Looking at Auriga in the sky, it is easy to consider Elnath as part of Auriga. In the past it has been designated as Gamma Aurigae, although it actually now lies over the border in the constellation of Taurus. The name Gamma Aurigae is rarely used anymore for Elnath. The Milky Way runs right through the middle of Auriga, with lots of rich open clusters and nebulae. These include M36, M37 and M38, as well as two large emission nebula complexes - IC 410 and IC 405, the Flaming Star Nebula. The very large but extremely faint supernova remnant Simeis 147 straddles the border between Auriga and Taurus, three degrees east of Elnath. In the sky, Auriga lies opposite the center of our galaxy in Sagittarius. As we look at Auriga, we are looking out into the Perseus arm, an outer spiral arm of Milky Way. Auriga was cataloged by the Greek astronomer Ptolemy in the second century C.E. (Common Era). It is the 21st largest of today's 88 modern constellations, covering 657 square degrees of sky. North is to the top right in the above image.
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