Beta Aurigae

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Binary star system in the northern constellation of Auriga

title: "Beta Aurigae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["m-type-main-sequence-stars", "a-type-main-sequence-stars", "am-stars", "algol-variables", "triple-star-systems", "ursa-major-moving-group", "auriga", "bayer-objects", "bright-star-catalogue-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "stars-with-proper-names"] description: "Binary star system in the northern constellation of Auriga" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Beta_Aurigae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

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

| name = β Aurigae | image= |image=Auriga constellation map.svg|alt=|float=center|width=240 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=β Aurigae |x=382|y=306 |caption=Location of β Aurigae (circled) | epoch = J2000.0 | constell = Auriga | ra = | dec = | appmag_v = (2.602 + 2.705) | type = Main sequence | class = A1m IV + A1m IV | r-i = −0.01 | b-v = +0.03 | u-b = +0.05 | variable = Algol variable | radial_v = −18.2 | prop_mo_ra = −56.44 | prop_mo_dec = −0.95 | pm_footnote = | parallax = 40.21 | p_error = 0.23 | parallax_footnote = | absmag_v = 0.674 / 0.777 | reference =
| period_unitless = 3.96004 days | axis = | axis_unitless = AU | eccentricity = 0.0 | inclination = 76.0 ± 0.4 | node = | periastron = 54539.0162 ± 0.0003 reduced HJD | periarg = | k1 = | k2 = | component1 = β Aur Aa | mass = | radius = | luminosity = | temperature = 8,985 | metal_fe = | gravity = 3.93 | rotational_velocity = 33 | age_myr = | component2 = β Aur Ab | mass2 = | radius2 = | luminosity2 = | rotational_velocity2 = 34 | temperature2 = 8,760 | age_myr2 = | names = | Simbad=bet+Aur

Beta Aurigae is a binary star system in the northern constellation of Auriga. Its identifier is a Bayer designation that is Latinized from β Aurigae, and abbreviated Beta Aur or β Aur. This star has the official name Menkalinan, pronounced . The combined apparent visual magnitude of the system is 1.9, making it the second-brightest member of the constellation after Capella. Using the parallax measurements made during the Hipparcos mission, the distance to this star system can be estimated as 81.1 ly, give or take a half-light-year margin of error. It is drifting closer to the Sun with a radial velocity of −18 km/s.

Along their respective orbits around the Milky Way, Beta Aurigae and the Sun are closing in on each other, so that in around one million years it will become the brightest star in the night sky. It is predicted to come as close as 9.72 pc in 1.31 million years.

Nomenclature

::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/5a/Astronomer_Edward_Charles_Pickering's_Harvard_computers.jpg" caption="access-date=28 July 2016}} included a table of the first two batches of names approved by the WGSN; which included ''Menkalinan'' for this star."] ::

It is known as 五車三 (the Third Star of the Five Chariots) in traditional Chinese astronomy.

Properties

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b6/BetaAurLightCurve.png" caption="A [[light curve]] for Beta Aurigae, plotted from data published by Southworth ''et al.'' (2007)"] ::

Beta Aurigae is a binary star system, but it appears as a single star in the night sky. The two stars are metallic-lined stars belonging to the A-type stellar classification. Although the spectra have the luminosity class of a subgiant (IV), the components are still on the main sequence stage of evolution. This discrepancy arises from their nature as Am stars, which make them larger and more luminous than a "normal" star. A-type stars are hot and release a white hued light; these two stars burn brighter and with more heat than the Sun, which is a G2-type main sequence star. The pair constitute an eclipsing spectroscopic binary; the combined apparent magnitude varies over a period of 3.96 days between +1.89 and +1.94, as every 47.5 hours one of the stars partially eclipses the other from Earth's perspective. The two stars are designated Aa and Ab in modern catalogues, but have also been referred to as components 1 and 2 or A and B.

There is an 11th magnitude optical companion with a separation of as of 2011, but increasing. It is also an A-class subgiant, but is an unrelated background star.

At an angular separation of along a position angle of 155° is a companion star that is 8.5 magnitudes fainter than the primary. It may be the source of the X-ray emission from the vicinity. The Beta Aurigae system is believed to be a stream member of the Ursa Major Moving Group.

References

| display-authors=1 | last1=Mason | first1=Brian D. | last2=Wycoff | first2=Gary L. | last3=Hartkopf | first3=William I. | last4=Douglass | first4=Geoffrey G. | last5=Worley | first5=Charles E. | title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog | journal=The Astronomical Journal | volume=122 | issue=6 | pages=3466–3471 | date=December 2001 | doi=10.1086/323920| doi-access=free | bibcode=2001AJ....122.3466M }}

| display-authors=1 | last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N. | title=General Catalogue of Variable Stars | version=5.1 | journal=Astronomy Reports | year=2017 | volume=61 | issue=1 | pages=80–88 | bibcode=2017ARep...61...80S | s2cid=125853869 | doi=10.1134/S1063772917010085 }}

| last1=Kunitzsch |first1=Paul | last2=Smart |first2=Tim | date=2006 | edition=2nd rev. | title=A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations | publisher=Sky Pub | location=Cambridge, Massachusetts | isbn=978-1-931559-44-7 }}

| url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names | publisher=International Astronomical Union | access-date=28 July 2016 }}

| last=Tomkin | first=Jocelyn | date=April 1998 | title=Once and Future Celestial Kings | journal=Sky and Telescope | volume=95 | issue=4 | pages=59–63 | bibcode=1998S&T....95d..59T }} – based on computations from HIPPARCOS data. (The calculations exclude stars whose distance or proper motion is uncertain.) [ftp://tlgleonid.asuscomm.com/HITACHI/BOOK_ASTRO/S&T/SkyandTelescope_1998%20-%20astronomy/04/199804059063.pdf PDF]

| postscript=. | title=IAU Working Group on Star Names (WGSN) | publisher=International Astronomical Union | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | access-date=22 May 2016 | archive-date=10 June 2016 | archive-url=https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead

| title=Close encounters of the stellar kind | last=Bailer-Jones | first=C. A. L. | journal=Astronomy & Astrophysics | volume=575 | id=A35 | pages=13 | date=March 2015 | doi=10.1051/0004-6361/201425221 | arxiv=1412.3648 | bibcode=2015A&A...575A..35B | s2cid=59039482 }}

References

  1. "Bulletin of the IAU Working Group on Star Names, No. 1".
  2. van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
  3. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory.
  4. (1994). "Radii and masses for beta Aurigae". Astronomy and Astrophysics.
  5. (February 2010). "Accurate masses and radii of normal stars: modern results and applications". The Astronomy and Astrophysics Review.
  6. Wilson, R. E.. (1953). "General Catalogue of Stellar Radial Velocities". [[Carnegie Institute of Washington D.C.]].
  7. (July 2011). "Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. II. Orbits of Double-lined Spectroscopic Binaries". The Astronomical Journal.
  8. (2023-08-17). "The Mass–Temperature Relation for B and Early A Stars Based on International Ultraviolet Explorer Spectra of Detached Eclipsing Binaries". The Astronomical Journal.
  9. (January 2010). "Synchronization and circularization in early-type binaries on main sequence". Monthly Notices of the Royal Astronomical Society.
  10. (2007-04-01). "Effect of tidal evolution in determining the ages of eclipsing-variable early main sequence close binary systems". Springer Nature.
  11. (September 2008). "A catalogue of multiplicity among bright stellar systems". [[Monthly Notices of the Royal Astronomical Society]].
  12. "bet Aur".
  13. (July 2011). "The Volume-limited A-Star (VAST) survey - I. Companions and the unexpected X-ray detection of B6-A7 stars". Monthly Notices of the Royal Astronomical Society.
  14. (June 2007). "Eclipsing binaries observed with the WIRE satellite. II. β Aurigae and non-linear limb darkening in light curves". Astronomy and Astrophysics.
  15. (2020-02-01). "A study of the physical properties of SB2s with both the visual and spectroscopic orbits". Monthly Notices of the Royal Astronomical Society.
  16. (February 2006). "A catalogue of eclipsing variables". Astronomy and Astrophysics.
  17. (August 1979). "On the eclipsing binaries of the Ursa Major stream". Astronomy and Astrophysics.

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m-type-main-sequence-starsa-type-main-sequence-starsam-starsalgol-variablestriple-star-systemsursa-major-moving-groupaurigabayer-objectsbright-star-catalogue-objectsdurchmusterung-objectsflamsteed-objectshenry-draper-catalogue-objectshipparcos-objectsstars-with-proper-names