Sigma Aurigae

Sigma Aurigae is a star in the northern constellation of Auriga. Its name is a Bayer designation that is Latinized from σ Aurigae, and abbreviated Sigma Aur or σ Aur. This star is faintly visible to the naked eye with an apparent visual magnitude of 4.99. With an annual parallax shift of 6.35 mas, it is approximately distant from the Earth. It is drifting closer to the Sun with a radial velocity of −20 km/s.
This is an evolved giant star with a stellar classification of K3III CN+2, indicating that it has exhausted the supply of hydrogen at its core. The 'CN+2' notation indicates anomalously strong lines of the CN molecule in the spectrum. This star has expanded to 44 times the radius of the Sun and is radiating nearly 500 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,120 K. There is a 12th magnitude companion at an angular separation of 8 arcseconds, as well as two fainter companions at 28 and 35" respectively. All are background objects, stars much further away than Sigma itself.
Sigma Aurigae, along with λ Aur and μ Aur, were Kazwini's Al Ḣibāʽ, the Tent. According to the catalogue of stars in the Technical Memorandum 33-507 – A Reduced Star Catalog Containing 537 Named Stars, Al Ḣibāʽ were the title for three stars: λ Aur as Al Ḣibāʽ I, μ Aur as Al Ḣibāʽ II and σ Aur as Al Ḣibāʽ III.