28 Monocerotis

28 Monocerotis is a single[11] star in the equatorial constellation of Monoceros. It has an orange-hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.69.[2] The distance to this star is approximately 450 light years based on parallax,[1] and it has an absolute magnitude of −1.00.[2] The star is drifting further away from the Sun with a radial velocity of +26.7 km/s.[5]

28 Monocerotis
Observation data
Epoch J2000      Equinox J2000
Constellation Monoceros
Right ascension 08h 01m 13.33574s[1]
Declination −1° 23′ 33.3935″[1]
Apparent magnitude (V) 4.69[2]
Characteristics
Spectral type K4III[3]
U−B color index +1.76[4]
B−V color index +1.49[4]
Astrometry
Radial velocity (Rv)+26.70[5] km/s
Proper motion (μ) RA: +67.60[1] mas/yr
Dec.: -76.26[1] mas/yr
Parallax (π)7.25 ± 0.30[1] mas
Distance450 ± 20 ly
(138 ± 6 pc)
Absolute magnitude (MV)−1.00[2]
Details
Mass2.193±0.110[6] M☉
Radius47.69+0.46
−2.21[7] R☉
Luminosity524±42[7] L☉
Surface gravity (log g)1.68[8] cgs
Temperature3,999+96
−19[7] K
Metallicity [Fe/H]−0.26[2] dex
Rotational velocity (v sin i)2.2[9] km/s
Other designations
V645 Mon, BD−00 1882, FK5 2620, GC 10870, HD 65953, HIP 39211, HR 3141, SAO 135380[10]
Database references
SIMBADdata

This is an aging giant star with a stellar classification of K4III,[3] having exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. The spectrum of the star shows abnormally strong lines of CN.[12] It is a rapidly rotating FK Comae Berenices variable, with a magnitude varying by 0.02 over a period of 0.21 days.[13][14] The star has expanded to 48 times the radius of the Sun. It is radiating 524 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,999 K.[7]

Measurement of the star's proper motion anomaly by the Gaia spacecraft suggests a companion may be orbiting the star at a distance of 1.9 AU.[6]

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. 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
  3. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  4. Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  5. 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.
  6. Kervella, Pierre; et al. (March 2019). "Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly". Astronomy & Astrophysics. 623: 23. arXiv:1811.08902. Bibcode:2019A&A...623A..72K. doi:10.1051/0004-6361/201834371. A72.
  7. 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.
  8. Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497.
  9. 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
  10. "28 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-10-20.
  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.
  12. Eggen, Olin J. (October 1996). "Star Streams and Galactic Structure". Astronomical Journal. 112: 1595. Bibcode:1996AJ....112.1595E. doi:10.1086/118126.
  13. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....1.2025S.
  14. Stift, M. J. (January 1979). "5-hour Light Variation of HD 65953 (28 Mon)?". Information Bulletin on Variable Stars. 1542: 1. Bibcode:1979IBVS.1542....1S.
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