Gamma Columbae

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 mas[1]
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)3.328±0.100[10] cgs
Temperature15570±320[10] K
Rotational velocity (v sin i)96±16 km/s
Age23.6±2.0[11] Myr
γ Col B
Mass0.94[2] M☉
Temperature5,367[2] K
Other designations
γ Col, CD−35°2612, HD 40494, HIP 28199, HR 2106, SAO 196352.[12]
Database references
SIMBADdata

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.

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.[11] At this age, it is thought to be the remnant of a once more massive star that just finished hydrogen fusion, and is undergoing structural readjustment. This process is extremely short, on the order of ten thousand years, making it a rare object.[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]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Gerbaldi2001 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Hiltner1969 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Huelamo2000 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Johnson1999 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference Hubrig2009 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  10. ^ a b c Irrgang, Andreas; Przybilla, Norbert; Meynet, Georges (2022). "γ Columbae as a recently stripped pulsating core of a massive star". Nature Astronomy. 6 (12): 1414–1420. arXiv:2211.00358. Bibcode:2022NatAs...6.1414I. doi:10.1038/s41550-022-01809-6. S2CID 253244604.
  11. ^ a b Cite error: The named reference tetzlaff2011 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).