Epsilon Columbae

Epsilon Columbae, Latinized from ε Columbae, is a star in the southern constellation of Columba. It is visible to the naked eye, having an apparent visual magnitude of 3.87.[2] Based upon an annual parallax shift of 12.46 mas,[1] it is located approximately 262 light years distant from the Sun. The star is drifting closer with a radial velocity of −5 km/s.[5]

ε Columbae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Columba
Right ascension 05h 31m 12.74899s[1]
Declination −35° 28′ 13.8605″[1]
Apparent magnitude (V) 3.87[2]
Characteristics
Spectral type K1 II/III[3] or K1 IIIa[4]
U−B color index +1.08[2]
B−V color index +1.14[2]
Astrometry
Radial velocity (Rv)−4.9[5] km/s
Proper motion (μ) RA: +26.421[1] mas/yr
Dec.: −30.085[1] mas/yr
Parallax (π)12.4610 ± 0.2423 mas[1]
Distance262 ± 5 ly
(80 ± 2 pc)
Absolute magnitude (MV)−0.67[6]
Details
Mass2.47[7] M☉
Radius25.2+3.1
−2.0[1] R☉
Luminosity251.2±5.6[1] L☉
Surface gravity (log g)2.05[4] cgs
Temperature4,575+195
−260[1] K
Metallicity [Fe/H]−0.03[4] dex
Age1.53[7] Gyr
Other designations
ε Col, CD−35° 2348, FK5 2413, HD 36597, HIP 25859, HR 1862, SAO 195924[8]
Database references
SIMBADdata

This is an orange-hued[9] K-type giant star with a stellar classification of K1 II/III.[3] At the age of 1.5[7] billion years old, it has exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. Epsilon Columbae has 2.5[7] times the mass and 25[1] times the radius of the Sun. The star radiates 251 times the solar luminosity from its enlarged photosphere at an effective temperature of 4,575 K.[1] It has a peculiar velocity of 30.0±3.9 km/s, making it a candidate runaway star system.[10] Based upon changes in the star's movement, it has an orbiting stellar companion of unknown type.[11]

References
  1. 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.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. Houk, Nancy (1982), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 3, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
  4. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
  5. Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
  6. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
  8. "eps Col". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-12-22.{{cite web}}: CS1 maint: postscript (link)
  9. Kambic, Bojan (2009), Viewing the Constellations with Binoculars: 250+ Wonderful Sky Objects to See and Explore, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media, p. 260, ISBN 978-0387853550.
  10. Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
  11. 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, S2CID 14878976.
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