Gamma Columbae

Gamma Columbae, Latinized from γ Columbae, is a possible wide binary star system[2] in the southern constellation of Columba. It is visible to the naked eye with an apparent visual magnitude of 4.36.[5] Based upon an annual parallax shift of 3.75 mas,[1] it is located roughly 870 light years from the Sun.

γ Columbae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Columba
Right ascension 05h 57m 32.20958s[1]
Declination −35° 16′ 59.8153″[1]
Apparent magnitude (V) 4.366 + 12.664[2]
Characteristics
Spectral type B2.5 IV[3] + G8 V[4]
U−B color index −0.66[5]
B−V color index −0.18[5]
Variable type Candidate SPB[6]
Astrometry
Radial velocity (Rv)+24.2[7] km/s
Proper motion (μ) RA: −3.24[1] mas/yr
Dec.: +10.21[1] mas/yr
Parallax (π)3.75 ± 0.18[1] mas
Distance870 ± 40 ly
(270 ± 10 pc)
Absolute magnitude (MV)−2.76[8]
Details[6]
γ Col A
Mass5.7±0.3 M☉
Radius4.8±0.4 R☉
Luminosity2,070[9] L☉
Surface gravity (log g)3.72±0.20 cgs
Temperature12,904[9] K
Rotational velocity (v sin i)96±16 km/s
Age23.6±2.0[10] Myr
γ Col B
Mass0.94[2] M☉
Temperature5,367[2] K
Other designations
γ Col, BD−35° 2612, HD 40494, HIP 28199, HR 2106, SAO 196352.[11]
Database references
SIMBADdata

The primary component is an evolved[6] B-type subgiant star with a stellar classification of B2.5 IV.[3] It is a candidate slowly pulsating B-type star with a mean longitudinal magnetic field strength of 94±28 G.[6] The star has nearly six times the mass of the Sun and close to five times the Sun's girth.[6] It is radiating over 2,000 times the solar luminosity from its outer atmosphere at an effective temperature of 12,904 K.[9] The estimated age of this star is around 24 million years.[10]

The visual magnitude 12.664[2] companion is a G-type main sequence star with a classification of G8 V.[4] It lies at an angular separation of 33.8 arc seconds from the primary, which corresponds to a projected physical separation of 8,844 AU.[2] Despite the young age of these stars, there has been no X-ray emission detected.[2]

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. Gerbaldi, M.; et al. (November 2001), "Binary systems with post-T Tauri secondaries", Astronomy and Astrophysics, 379: 162–184, Bibcode:2001A&A...379..162G, doi:10.1051/0004-6361:20011298.
  3. Hiltner, W. A.; et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal, 157: 313–326, Bibcode:1969ApJ...157..313H, doi:10.1086/150069.
  4. Huélamo, N.; et al. (July 2000), "X-ray emission from Lindroos binary systems", Astronomy and Astrophysics, 359: 227–241, arXiv:astro-ph/0005348, Bibcode:2000A&A...359..227H.
  5. Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1999), "UBVRIJKL photometry of the bright stars", Commission Lunar and Planetary Laboratory, 4: 99, Bibcode:1966CoLPL...4...99J.
  6. Hubrig, S.; et al. (April 2009), "New magnetic field measurements of β Cephei stars and slowly pulsating B stars", Astronomische Nachrichten, 330 (4): 317, arXiv:0902.1314, Bibcode:2009AN....330..317H, doi:10.1002/asna.200811187.
  7. Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institution for Science, Bibcode:1953GCRV..C......0W, LCCN 54001336.
  8. 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.
  9. McDonald, I.; et al. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x.
  10. Tetzlaff, N.; et al. (2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410: 190, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
  11. "gam Col -- Variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-19.
  • Kaler, James B. (January 29, 2016), "Gamma Columbae", STARS, University of Illinois, retrieved 2016-12-21.
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