Astronomy:18 Monocerotis
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 06h 47m 51.64752s[1] |
| Declination | 2° 24′ 43.7737″[1] |
| Apparent magnitude (V) | 4.47[2] |
| Characteristics | |
| Spectral type | K0+IIIaBa0.2[3] |
| U−B color index | +1.04[2] |
| B−V color index | +1.11[2] |
| Astrometry | |
| Radial velocity (Rv) | +11.29[4] km/s |
| Proper motion (μ) | RA: -16.898[1] mas/yr Dec.: -16.229[1] mas/yr |
| Parallax (π) | 8.0947 ± 0.2385[1] mas |
| Distance | 400 ± 10 ly (124 ± 4 pc) |
| Absolute magnitude (MV) | -0.78[5] |
| Orbit[6][7] | |
| Primary | 18 Monocerotis A |
| Companion | 18 Monocerotis B |
| Period (P) | 1760.9±1.9 d |
| Semi-major axis (a) | 6.63 mas |
| Eccentricity (e) | 0.40±0.04 |
| Inclination (i) | 96.25° |
| Longitude of the node (Ω) | 47.63° |
| Periastron epoch (T) | 2441942.5 |
| Argument of periastron (ω) (secondary) | 172±6° |
| Details | |
| 18 Mon A | |
| Radius | 26.95+1.56 −0.81[1] R☉ |
| Luminosity | 311.2±10.5[1] L☉ |
| Surface gravity (log g) | 2.59[8] cgs |
| Temperature | 4,750[9] K |
| Metallicity [Fe/H] | -0.03[5] dex |
| Rotational velocity (v sin i) | < 2.0[10] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
18 Monocerotis is a binary star system located about half way from Orion's Belt to Procyon,[6] in the equatorial constellation of Monoceros.[11] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.47,[2] and is positioned around 370[1] light years away from the Sun based on parallax. The system is receding from the Earth with a heliocentric radial velocity of +11 km/s.[4]
It is reported as a single-lined spectroscopic binary with an orbital period of 1,760.9 days (4.8 years) and an eccentricity of 0.4.[6] The visible component is an aging K-type giant star with a stellar classification of K0+IIIaBa0.2,[3] showing a slight overabundance of barium. The spectrum displays strong violet lines of CN.[6] With the supply of hydrogen at its core exhausted, this star has expanded to 27[1] times the radius of the Sun. It is radiating 311[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,750 K.[9]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 3.0 3.1 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.
- ↑ 4.0 4.1 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: 165–186. doi:10.1051/0004-6361:20041272. Bibcode: 2005A&A...430..165F.
- ↑ 5.0 5.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. Vizier catalog entry
- ↑ 6.0 6.1 6.2 6.3 Griffin, R. F. (1984). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 59: 18 Monocerotis". The Observatory 104: 267. Bibcode: 1984Obs...104..267G.
- ↑ ESA (1997). "The Hipparcos and Tycho Catalogues". VizieR On-line Data Catalog. Bibcode: 1997yCat.1239....0E.
- ↑ Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics 591: A118. doi:10.1051/0004-6361/201628497. Bibcode: 2016A&A...591A.118S.
- ↑ 9.0 9.1 Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters 34 (11): 785–796. doi:10.1134/S1063773708110078. Bibcode: 2008AstL...34..785G. Vizier catalog entry
- ↑ 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. doi:10.1051/aas:1999401. Bibcode: 1999A&AS..139..433D. Vizier catalog entry
- ↑ 11.0 11.1 "18 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=18+Mon.
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