Epsilon Canis Minoris

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Epsilon Canis Minoris
Epsilon canis minoris diagram.png
Star map of the 25 brightest stars in Canis Minor. Epsilon Canis Minoris is circled.
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Canis Minor
Right ascension 07h 25m 38.89613s[1]
Declination +09° 16′ 33.9541″[1]
Apparent magnitude (V) +5.002[2]
Spectral type G6.5 IIb[3]
U−B color index +0.774[2]
B−V color index +1.004[2]
Radial velocity (Rv) −7.8±1.3[4] km/s
Proper motion (μ) RA: −4.30[1] mas/yr
Dec.: −8.20[1] mas/yr
Parallax (π) 3.13 ± 0.30[1] mas
Distance 1,040 ± 100 ly
(320 ± 30 pc)
Absolute magnitude (MV) −2.62[5]
Mass 4.63±0.17 M
Radius 45.51±4.34 R
Luminosity 1,086.5±197.8 L
Surface gravity (log g) 1.81±0.06 cgs
Temperature 4,916±70 K
Metallicity [Fe/H] −0.12±0.10 dex
Rotational velocity (v sin i) 8[7] km/s
Age 140±10 Myr
Other designations
ε CMi, 2 CMi, BD+09° 1643, GC 9908, HD 58367, HIP 36041, HR 2828, SAO 115425[8]
Database references

Epsilon Canis Minoris (ε Canis Minoris) is a suspected binary star[9] system in the equatorial constellation of Canis Minor. It is a fifth magnitude star, which means it is bright enough to be faintly visible to the naked eye.[2] Based upon an annual parallax shift of just 3.13 mas as seen from Earth,[1] this star is located roughly 1,040 light years from the Sun, give or take a hundred light year margin of error.

This is an evolved G-type bright giant star with a stellar classification of G6.5 IIb.[3] It is most likely (99% chance) on the horizontal branch,[6] and is a barium star that shows an abnormal overabundance of barium in its spectrum.[10] This s-process element may have been accreted from a now white dwarf companion during a previous stage of its evolution.[9] The bright giant component has an estimated 4.63 times the mass of the Sun and has expanded to 45.5 times the Sun's radius. The star is radiating 1,087 times the Sun's luminosity from its enlarged photosphere at an effective temperature of about 4,916 K.[6]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172 (3): 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667. 
  3. ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series (ISSN 0067-0049), 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373. 
  4. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, Bibcode:2012A&A...546A..61D, arXiv:1208.3048Freely accessible, doi:10.1051/0004-6361/201219219, A61. 
  5. ^ Takeda, Yoichi; et al. (August 2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, Bibcode:2008PASJ...60..781T, arXiv:0805.2434Freely accessible, doi:10.1093/pasj/60.4.781. 
  6. ^ a b c Reffert, Sabine; et al. (2015), "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity", Astronomy and Astrophysics, 574A (2): 116–129, Bibcode:2015A&A...574A.116R, arXiv:1412.4634Freely accessible, doi:10.1051/0004-6361/201322360.  Values are based on 99% probability it is on the horizontal branch.
  7. ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B. 
  8. ^ "eps CMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-03. 
  9. ^ a b Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  10. ^ Williams, P. M. (February 1975), "Stellar compositions from narrow-band photometry - V. Barium abundances for 200 evolved stars", Monthly Notices of the Royal Astronomical Society, 170: 343−362, Bibcode:1975MNRAS.170..343W, doi:10.1093/mnras/170.2.343.