Capella
Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur.
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Source: Wikipedia (CC BY-SA)
Capella
Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur. Capella is the sixth-brightest star in the night sky, and the third-brightest in the northern celestial hemisphere after Arcturus and Vega.
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Why Capella matters:
Stars are the engines of the cosmos -- they forge the chemical elements, light up galaxies, and create the conditions that make planets and life possible.
A prominent object in the northern sky, it is circumpolar to observers north of 44°N. Its name meaning "little goat" in Latin, Capella depicted the goat Amalthea that suckled Zeus in classical mythology. Capella is relatively close, at 42.9 light-years (13.2 parsecs). It is one of the brightest X-ray sources in the sky, thought to come primarily from the corona of Capella Aa. Although it appears to be a single star to the naked eye, Capella is actually a quadruple star system organized in two binary pairs stars: the primary pair Capella Aa and Capella Ab; and the secondary pair Capella H and Capella L. The primaries are two bright-yellow giant stars, both of which are around 2.5 Solar masses. The secondary pair, are around 10,000 astronomical units (AU) from the first. They are faint, small and relatively cool red dwarfs. Capella Aa and Capella Ab have exhausted their core hydrogen, and cooled and expanded, moving off the main sequence. They are in a very tight circular orbit about 0.74 AU apart, and orbit each other every 104 days. Capella Aa is the cooler and more luminous of the two with spectral class G8III; it is 78.7±4.2 times the Sun's luminosity and 11.98±0.57 times its radius. An aging red clump star, it is fusing helium to carbon and oxygen in its core. Capella Ab is slightly smaller and hotter and of spectral class G0III; it is 72.7±3.6 times as luminous as the Sun and 8.83±0.33 times its radius. It is in the Hertzsprung gap, corresponding to a brief subgiant evolutionary phase as it expands and cools to become a red giant. Several other stars in the same visual field have been catalogued as companions but are physically unrelated.
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Deep dive: Capella
Its name meaning "little goat" in Latin, Capella depicted the goat Amalthea that suckled Zeus in classical mythology. Capella is relatively close, at 42.9 light-years (13.2 parsecs). It is one of the brightest X-ray sources in the sky, thought to come primarily from the corona of Capella Aa. Although it appears to be a single star to the naked eye, Capella is actually a quadruple star system organized in two binary pairs stars: the primary pair Capella Aa and Capella Ab; and the secondary pair Capella H and Capella L. The primaries are two bright-yellow giant stars, both of which are around 2.5 Solar masses. The secondary pair, are around 10,000 astronomical units (AU) from the first. They are faint, small and relatively cool red dwarfs. Capella Aa and Capella Ab have exhausted their core hydrogen, and cooled and expanded, moving off the main sequence. They are in a very tight circular orbit about 0.74 AU apart, and orbit each other every 104 days. Capella Aa is the cooler and more luminous of the two with spectral class G8III; it is 78.7±4.2 times the Sun's luminosity and 11.98±0.57 times its radius. An aging red clump star, it is fusing helium to carbon and oxygen in its core. Capella Ab is slightly smaller and hotter and of spectral class G0III; it is 72.7±3.6 times as luminous as the Sun and 8.83±0.33 times its radius. It is in the Hertzsprung gap, corresponding to a brief subgiant evolutionary phase as it expands and cools to become a red giant. Several other stars in the same visual field have been catalogued as companions but are physically unrelated.
Source: https://en.wikipedia.org/wiki/Capella (Wikipedia, CC BY-SA)
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