Chi Aurigae

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title: "Chi Aurigae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["b-type-supergiants", "spectroscopic-binaries", "auriga", "bayer-objects", "bright-star-catalogue-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects"] description: "Binary star system in the constellation Auriga" topic_path: "general/b-type-supergiants" source: "https://en.wikipedia.org/wiki/Chi_Aurigae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Binary star system in the constellation Auriga ::

| image = | image=Auriga IAU.svg | float=center | width=250 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=χ Aur | x%=55.0 | y%=57.0 | caption = The location of χ Aurigae (circled) | epoch = J2000 | ra = | dec = | appmag_v = 4.74 | constell = Auriga | class = B5 Iab | r-i = | v-r = | b-v = +0.32 | u-b = −0.44 | variable = | radial_v = 7.27 | prop_mo_ra = −0.812 | prop_mo_dec = −3.15 | pm_footnote = | parallax = 0.9087 | p_error = 0.1906 | parallax_footnote = | dist_pc = | dist_ly = | dist_footnote = | absmag_v = −6.4 | reference = | period_unitless = 676.85 ± 0.21 d | eccentricity = 0.116 ± 0.048 | node = 181.7° ± 24.3 | periastron = 2422754.2 ± 46.1 HJD | k1 = 22.0 ± 2.9 | mass = | radius = | luminosity = | temperature = | metal_fe = | gravity = | rotational_velocity = 40 | age_myr = 8.7 | names = | Simbad=chi+Aur

Chi Aurigae is a binary star system in the northern constellation of Auriga. Its name is a Bayer designation that is Latinized from χ Aurigae, and abbreviated Chi Aur or χ Aur. This star is visible to the naked eye with an apparent visual magnitude of 4.74. The brightness of the star is diminished by 1.26 in magnitude from extinction caused by intervening gas and dust. It is a member of the Aur OB1 association of co-moving stars.

Chi Aurigae is a single-lined spectroscopic binary with an orbital period of 676.85 d and an eccentricity of 0.116. 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 than the Sun. The photosphere has an effective temperature of 14,600 K. Its stellar wind is causing mass loss at the rate of solar masses per year, or the equivalent of the Sun's mass every 2.4 billion years.

The distance of Chi Aurigae is determined at 3,900 light-years based on spectroscopic observations. Parallax measurements by the Hipparcos spacecraft were unsuccessful 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 .

References

References

1. {{Cite DR3. 3448691754658000640
2. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
3. Lesh, Janet Rountree. (December 1968). "The Kinematics of the Gould Belt: an Expanding Group?". Astrophysical Journal Supplement.
4. (July 2002). "Rotational Velocities of B Stars". The Astrophysical Journal.
5. (1971). "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere". The Astronomical Journal.
6. Weßmayer, D.. (December 2022). "Quantitative spectroscopy of B-type supergiants". [[Astronomy & Astrophysics]].
7. (October 2010). "Signature of wide-spread clumping in B supergiant winds". Astronomy and Astrophysics.
8. (March 1998). "Hα variability of the B-type binary chi Aurigae". Astronomy and Astrophysics.
9. "* chi Aur".

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