20 Monocerotis

20 Monocerotis is a single[9] star located about 194[1] light years away from the Sun in the equatorial constellation of Monoceros. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.92.[2] The star is receding from the Earth with a heliocentric radial velocity of +78 km/s.[5]

20 Monocerotis
Location of 20 Monocerotis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Monoceros
Right ascension  07h 10m 13.68177s[1]
Declination −04° 14′ 13.5829″[1]
Apparent magnitude (V) 4.92[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type K0III[4]
U−B color index +0.78[2]
B−V color index +1.03[2]
Astrometry
Radial velocity (Rv)+77.74[5] km/s
Proper motion (μ) RA: −0.714[1] mas/yr
Dec.: +217.298[1] mas/yr
Parallax (π)16.8419 ± 0.1692[1] mas
Distance194 ± 2 ly
(59.4 ± 0.6 pc)
Absolute magnitude (MV)0.94[6]
Details[7]
Mass1.07±0.20 M☉
Radius10.25±0.11[1] R☉
Luminosity46.36±0.56[1] L☉
Surface gravity (log g)2.53±0.10 cgs
Temperature4,714±46 K
Metallicity [Fe/H]−0.25±0.03 dex
Rotational velocity (v sin i)2.33±0.50 km/s
Age5.75±2.85 Gyr
Other designations
20 Mon, BD−04°1840, FK5 1186, GC 9477, HD 54810, HIP 34622, HR 2701, SAO 134282, CCDM J07102-0414A, WDS J07102-0414A[8]
Database references
SIMBADdata

This object is an aging giant star with a stellar classification of K0 III.[4] It is a red clump giant,[3] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is around six[7] billion years old with 1.1 times the mass of the Sun. After exhausting the supply of hydrogen at its core, it has expanded to 10.3[1] times the Sun's radius. It is radiating 46[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,714 K.[7]

In addition to the primary, three visual companions have been reported: component B, with magnitude 12.93 and separation 67.8", C, with magnitude 10.16 and separation 167.9", and D, with magnitude 12.46 and separation 102.3".[10]

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. 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. Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society, 408 (2): 1225–1232, arXiv:1006.3857, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x
  4. 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.
  5. Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. Vizier catalog entry
  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. Vizier catalog entry
  7. Jofré, E.; et al. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy and Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474.
  8. "20 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-31.
  9. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  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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