Gamma Monocerotis

γ Monocerotis, Latinised as Gamma Monocerotis, is a binary star[8] system in the equatorial constellation of Monoceros. Based upon an annual parallax shift of 6.55 mas,[1] it is located roughly 500 light years from the Sun. It can be viewed with the naked eye, having an apparent visual magnitude of 3.96.[2] Gamma Monocerotis is moving away from the Sun with a radial velocity of −5 km/s.[4]

γ Monocerotis
Location of γ Monocerotis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 14m 51.33367s[1]
Declination −06° 16′ 29.1880″[1]
Apparent magnitude (V) 3.96[2]
Characteristics
Spectral type K1.5IIIBa0.3[3]
U−B color index +1.42[2]
B−V color index +1.31[2]
Astrometry
Radial velocity (Rv)−4.8±0.7[4] km/s
Proper motion (μ) RA: −4.69[1] mas/yr
Dec.: −19.30[1] mas/yr
Parallax (π)6.55 ± 0.19[1] mas
Distance500 ± 10 ly
(153 ± 4 pc)
Absolute magnitude (MV)-1.93[5]
Details
Luminosity1021[5] L☉
Surface gravity (log g)1.61[6] cgs
Temperature4,375[6] K
Metallicity [Fe/H]−0.15[6] dex
Rotational velocity (v sin i)4.0[7] km/s
Other designations
γ Mon, 5 Monocerotis, BD−06° 1469, FK5 2475, GC 7986, HD 43232, HIP 29651, HR 2227, SAO 133012, CCDM J06149-0616A, WDS J06149-0617A
Database references
SIMBADdata

This is an evolved K-type giant star with a stellar classification of K1.5 III Ba0.3.[3] The Ba0.3 suffix indicates this is a mild barium star, which means the spectrum displays abnormal abundance of s-process elements, including barium. These were deposited by an orbiting companion as it passed through the asymptotic giant branch stage. The companion is now a white dwarf star.[9]

It has reported companions B, at separation 53.7" and magnitude 13.1, and C, at separation 47.9" and magnitude 13.6.[10]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  5. 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. Vizier catalog entry
  6. Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2010). "Coudé-feed stellar spectral library – atmospheric parameters". Astronomy & Astrophysics. 525: A71. arXiv:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014.
  7. De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. Vizier catalog entry
  8. 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.
  9. Yang, Guo-Chao; et al. (January 2016), "Chemical abundance analysis of 19 barium stars", Research in Astronomy and Astrophysics, 16 (1), arXiv:1602.08704, Bibcode:2016RAA....16...19Y, doi:10.1088/1674-4527/16/1/019, 19.
  10. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Vizier catalog entry
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