Chi Aurigae

Chi Aurigae, Latinized from χ Aurigae, is the Bayer designation for a binary star system in the northern constellation of Auriga. It is visible to the naked eye with an apparent visual magnitude of 4.74. The distance of Chi Aurigae is determined at 3,900 ly based on spectroscopic observations. Parallax measurements by the Hipparcos spacecraft were unsucessful because the parallax error was bigger than the value itself, while the Gaia spacecraft measured the parallax with a 22% error, giving a distance of $-0.812$. The brightness of the star is diminished by 1.26 in magnitude from extinction caused by intervening gas and dust.

Chi Aurigae is a spectroscopic binary with an orbital period of 676.85 d and an eccentricity of 0.12. The primary component of this system is a supergiant star with a stellar classification of B5 Iab. It is over 190,000 times more luminous, around 20 times more massive and around 70 times larger. Its surface has an effective temperature of 14,600 K. It has a stellar wind that is causing mass loss at the rate of 0.38–0.46 × 10−9 solar masses per year, or the equivalent of the Sun's mass every 2.4 billion years.