Epsilon Canis Majoris

"Adhara" redirects here. For other uses, see Adhara (disambiguation).
ε Canis Majoris
Location of ε Canis Majoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension 06h 58m 37.54876s[1]
Declination –28° 58′ 19.5102″[1]
Apparent magnitude (V) 1.50[2]
Characteristics
Spectral type B2 II[3]
U−B color index –0.93[2]
B−V color index –0.21[2]
Astrometry
Radial velocity (Rv)+27.3 km/s
Proper motion (μ) RA: +3.24 mas/yr[1]
Dec.: +1.33 mas/yr[1]
Parallax (π)7.57 ± 0.57 mas[1]
Distance430 ± 30 ly
(132 ± 10 pc)
Absolute magnitude (MV)–4.8[4]
Details
Mass12 to 13.1[5] M☉
Radius10.5[6] R☉
Luminosity22,400+2,700
−2,400[5] L☉
Surface gravity (log g)3.4±0.08[6] cgs
Temperature22,500±300[5] K
Rotational velocity (v sin i)25[7] km/s
Age17.5 – 19[6] Myr
Other designations
Adhara, Adharaz, Undara, ε CMa, 21 CMa, CD−28°3666, FK5 268, HD 52089, HIP 33579, HR 2618, SAO 172676, ADS 5654
Database references
SIMBADdata

Epsilon Canis Majoris is a binary star system and the second-brightest star in the constellation of Canis Major. Its name is a Bayer designation that is Latinised from ε Canis Majoris, and abbreviated Epsilon CMa or ε CMa. This is the 22nd-brightest star in the night sky with an apparent magnitude of 1.50. About 4.7 million years ago, it was the brightest star in the night sky, with an apparent magnitude of −3.99.[8] Based upon parallax measurements obtained during the Hipparcos mission, it is about 430 light-years distant from the Sun.[1]

The two components are designated ε Canis Majoris A, officially named Adhara /əˈdɛərə/ – the traditional name of the system,[9][10] and B.

  1. ^ a b c d e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
  3. ^ Cite error: The named reference mnras410_1_190 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference snow was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference fossati was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference magnetic was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference apj573_1_359 was invoked but never defined (see the help page).
  8. ^ Tomkin, Jocelyn (April 1998). "Once and Future Celestial Kings". Sky and Telescope. 95 (4): 59–63. Bibcode:1998S&T....95d..59T.
  9. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  10. ^ "Naming Stars (including "List of IAU-approved Star Names as of January 1st, 2021")". IAU.org. Retrieved 28 February 2021.