18 Monocerotis

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18 Monocerotis
Monoceros constellation map.svg
Red circle.svg
Location of 18 Monocerotis (circled red)
Observation data
Epoch J2000      Equinox J2000
Constellation Monoceros
Right ascension 06h 47m 51.64956s[1]
Declination 2° 24′ 43.7737″[1]
Apparent magnitude (V) 4.47[2]
Spectral type K0+IIIaBa0.2[3]
U−B color index +1.04[2]
B−V color index +1.11[2]
Radial velocity (Rv)+11.29[4] km/s
Proper motion (μ) RA: -12.41[1] mas/yr
Dec.: -12.12[1] mas/yr
Parallax (π)8.86 ± 0.40[1] mas
Distance370 ± 20 ly
(113 ± 5 pc)
Absolute magnitude (MV)-0.78[5]
Primary18 Monocerotis A
Companion18 Monocerotis B
Period (P)1760.9 days
Semi-major axis (a)6.63 mas
Eccentricity (e)0.4
Inclination (i)96.25°
Longitude of the node (Ω)47.63°
Periastron epoch (T)2441942.5
Argument of periastron (ω)
Luminosity273[5] L
Surface gravity (log g)2.59[7] cgs
Temperature4,750[8] K
Metallicity [Fe/H]-0.03[5] dex
Rotational velocity (v sin i)< 2.0[9] km/s
Other designations
BD+02 1397, FK5 258, GC 8892, HIP 32578, HR 2506, HD 49293, SAO 114428
Database references

18 Monocerotis is a class K0III[3] (orange giant) star in the constellation Monoceros. Its apparent magnitude is 4.47[2] and it is approximately 368 light years away based on parallax.[1]

It is reported as a spectroscopic binary with a period of 1760.9 days.[10]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d 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. ^ a b 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. ^ Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data". Astronomy & Astrophysics. 430: 165. arXiv:astro-ph/0409579Freely accessible. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. 
  5. ^ a b c Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971Freely accessible. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015.  Vizier catalog entry
  6. ^ ESA (1997). "The Hipparcos and Tycho Catalogues". VizieR On-line Data Catalog. Bibcode:1997yCat.1239....0E. 
  7. ^ Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384Freely accessible. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497. 
  8. ^ Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785. arXiv:1607.00619Freely accessible. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078.  Vizier catalog entry
  9. ^ De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series. 139 (3): 433. arXiv:astro-ph/0608248Freely accessible. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401.  Vizier catalog entry
  10. ^ Griffin, R. F. (1984). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 59: 18 Monocerotis". The Observatory. 104: 267. Bibcode:1984Obs...104..267G.