Epsilon Canis Minoris

Epsilon Canis Minoris (ε Canis Minoris) is a suspected binary star[10] 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 770 light years from the Sun, give or take a 40 light year margin of error.[5]

ε Canis Minoris
Location of ε Canis Minoris (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]
Characteristics
Spectral type G6.5 IIb[3]
U−B color index +0.774[2]
B−V color index +1.004[2]
Astrometry
Radial velocity (Rv)−7.8±1.3[4] km/s
Proper motion (μ) RA: −3.338 ± 0.385[5] mas/yr
Dec.: −8.497 ± 0.310[5] mas/yr
Parallax (π)4.2624 ± 0.2288[5] mas
Distance770 ± 40 ly
(230 ± 10 pc)
Absolute magnitude (MV)−2.62[6]
Details[7]
Mass4.63±0.17 M☉
Radius45.51±4.34 R☉
Luminosity1,086.5±197.8 L☉
Surface gravity (log g)1.81±0.06 cgs
Temperature4,916±70 K
Metallicity [Fe/H]−0.12±0.10 dex
Rotational velocity (v sin i)8[8] km/s
Age140±10 Myr
Other designations
ε CMi, 2 CMi, BD+09°1643, GC 9908, HD 58367, HIP 36041, HR 2828, SAO 115425[9]
Database references
SIMBADdata

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,[7] and is a barium star that shows an abnormal overabundance of barium in its spectrum.[11] This s-process element may have been accreted from a now white dwarf companion during a previous stage of its evolution.[10] 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.[7]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. 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. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 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, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  5. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  6. 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, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781.
  7. 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, arXiv:1412.4634, Bibcode:2015A&A...574A.116R, doi:10.1051/0004-6361/201322360, hdl:10722/215277. Values are based on 99% probability it is on the horizontal branch.
  8. 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.
  9. "eps CMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-03.
  10. 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  11. 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.
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