Location of ρ Capricorni (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 20 28 51.61448 |
| Declination | −17° 48′ 49.2693″ |
| Apparent magnitude (V) | +4.78 (4.97 + 6.88) |
| Characteristics | |
| Spectral type | F2 IV + G1 |
| Astrometry | |
| Radial velocity (Rv) | +18.4 km/s |
| Proper motion (μ) | RA: −14.98 mas/yr Dec.: −7.29 mas/yr |
| Parallax (π) | 33.04 ± 0.46 mas |
| Distance | 99 ± 1 ly (30.3 ± 0.4 pc) |
| Absolute magnitude (MV) | 2.52 + 4.56 |
| Orbit | |
| Period (P) | 278 yr |
| Semi-major axis (a) | 1.877″ |
| Eccentricity (e) | 0.91 |
| Inclination (i) | 113.3° |
| Longitude of the node (Ω) | 162.0° |
| Periastron epoch (T) | 1965.0 |
| Argument of periastron (ω) (secondary) | 144.5° |
| Details | |
| ρ Cap A | |
| Mass | 1.52±0.04 M☉ |
| Radius | 1.3 R☉ |
| Luminosity | 9 L☉ |
| Surface gravity (log g) | 4.02±0.03 cgs |
| Temperature | 6,911±63 K |
| Metallicity | −0.20±0.05 dex |
| Rotational velocity (v sin i) | 87.7 km/s |
| Age | 1.74±0.15 Gyr |
| Other designations | |
| ρ Cap, 11 Cap, ADS 13887, BD−18°5689, Gl 791.1, HD 194943, HIP 101027, HR 7822, SAO 163614, WDS J20289-1749AB | |
| Database references | |
| SIMBAD | ρ Cap |
| ρ Cap A | |
| ρ Cap B | |
| ARICNS | ρ Cap A |
| ρ Cap B | |
Rho Capricorni (ρ Cap, ρ Capricorni) is a binary star in the constellation Capricornus. Sometimes, this star is called by the name Bos, meaning the cow in Latin. In Chinese, 牛宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of β Capricorni, α Capricorni, ξ Capricorni, π Capricorni, ο Capricorni and ρ Capricorni. Consequently, the Chinese name for ρ Capricorni itself is 牛宿六 (Niú Su liù, English: the Sixth Star of Ox.)
This system is visible to the naked eye with a combined apparent visual magnitude of +4.78. The pair orbit each other with a period of 278 years and an eccentricity of 0.91. Based upon an annual parallax shift of 33.04 mas as seen from the Earth, the system is located about 99 light years from the Sun. It is a thin disk population star system that made its closest approach to the Sun about 1.6 million years ago when it came within 12.49 ly (3.830 pc).
The primary member, component A, is a yellow-white hued, F-type subgiant with an apparent magnitude of 4.97 and a stellar classification of F2 IV. This star has 1.5 times the mass of the Sun and 1.3 times the Sun's radius. It is radiating 9 times as much luminosity of the Sun from its outer atmosphere at an effective temperature of 6,911 K. The companion, component B, has a visual magnitude of 6.88. The mass ratio is 0.539, meaning the secondary is only 53.9% as massive as the primary.
References
- ^ van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M.
- ^ Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, archived from the original on 2005-04-24, retrieved 2017-05-12
- ^ Cvetkovic, Z.; Ninkovic, S. (June 2010), "On the Component Masses of Visual Binaries", Serbian Astronomical Journal, 180 (180): 71–80, Bibcode:2010SerAJ.180...71C, doi:10.2298/SAJ1080071C.
- Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
- ^ Ramírez, I.; et al. (September 2012), "Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets", The Astrophysical Journal, 756 (1): 46, arXiv:1207.0499, Bibcode:2012ApJ...756...46R, doi:10.1088/0004-637X/756/1/46, S2CID 119199829.
- ^ McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–357, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
- Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377
- "rho Cap -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-12.
- "Bos", constellationsofwords.com, retrieved 2017-05-12.
- (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 13 日 Archived 2011-05-22 at the Wayback Machine
- Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, S2CID 59039482, A35.
- Makarov, Valeri V.; Fabricius, Claus (2021). "Astrometric Mass Ratios of 248 Long-period Binary Stars Resolved in Hipparcos and Gaia EDR3". The Astronomical Journal. 162 (6): 260. arXiv:2109.11951. Bibcode:2021AJ....162..260M. doi:10.3847/1538-3881/ac2ee0. S2CID 237635330.
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