Astronomy:Epsilon Canis Minoris

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Short description: Suspected binary star system in the constellation Canis Minor
ε Canis Minoris
Location of ε Canis Minoris (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Canis Minor
Right ascension  07h 25m 38.900s[1]
Declination +09° 16′ 33.93″[1]
Apparent magnitude (V) +5.002[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type G6.5 IIb[4]
U−B color index +0.774[2]
B−V color index +1.004[2]
Astrometry
Radial velocity (Rv)−7.8±1.3[5] km/s
Proper motion (μ) RA: −4.583[1] mas/yr
Dec.: −8.414[1] mas/yr
Parallax (π)3.9908 ± 0.0811[1] mas
Distance820 ± 20 ly
(251 ± 5 pc)
Absolute magnitude (MV)−2.62[6]
Details[3]
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[7] km/s
Age140±10 Myr
Other designations
ε CMi, 2 CMi, BD+09°1643, GC 9908, HD 58367, HIP 36041, HR 2828, SAO 115425[8]
Database references
SIMBADdata

Epsilon Canis Minoris is a suspected binary star[9] system in the equatorial constellation of Canis Minor. Its name is a Bayer designation that is Latinized from ε Canis Minoris, and abbreviated Epsilon CMi or ε CMi. This 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 3.99 mas as seen from Earth, this star is located approximately 820 light years from the Sun, give or take a 20 light year margin of error.[1] It is drifting closer to the Sun with a line of sight velocity of −8 km/s.[5]

This is an evolved G-type bright giant star with a stellar classification of G6.5 IIb.[4] It is most likely (99% chance) on the horizontal branch,[3] 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.[3]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940.  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 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, doi:10.1093/mnras/172.3.667, Bibcode: 1975MNRAS.172..667J. 
  3. ↑ 3.0 3.1 3.2 3.3 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, doi:10.1051/0004-6361/201322360, Bibcode: 2015A&A...574A.116R.  Values are based on 99% probability it is on the horizontal branch.
  4. ↑ 4.0 4.1 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K. 
  5. ↑ 5.0 5.1 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D. 
  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, doi:10.1093/pasj/60.4.781, Bibcode: 2008PASJ...60..781T. 
  7. ↑ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago 239 (1): 1, Bibcode: 1970CoAsi.239....1B. 
  8. ↑ "eps CMi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eps+CMi. 
  9. ↑ 9.0 9.1 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  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 (2): 343–362, doi:10.1093/mnras/170.2.343, Bibcode: 1975MNRAS.170..343W. 



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