Astronomy:Rho Capricorni
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 20h 28m 51.615s[1] |
| Declination | −17° 48′ 49.26″[1] |
| Apparent magnitude (V) | +4.78[2] (4.97 + 6.88)[3] |
| Characteristics | |
| Spectral type | F2 IV[2] + G1[4] |
| B−V color index | 0.340/0.635[5] |
| Astrometry | |
| Radial velocity (Rv) | +18.4[6] km/s |
| Proper motion (μ) | RA: −16.889[1] mas/yr Dec.: −10.579[1] mas/yr |
| Parallax (π) | 33.2297 ± 0.2146[1] mas |
| Distance | 98.2 ± 0.6 ly (30.1 ± 0.2 pc) |
| Absolute magnitude (MV) | 2.52 + 4.56[4] |
| Orbit[3] | |
| 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[7] | |
| ρ Cap A | |
| Mass | 1.52±0.04 M☉ |
| Radius | 1.3[2] R☉ |
| Luminosity | 9[8] L☉ |
| Surface gravity (log g) | 4.02±0.03 cgs |
| Temperature | 6,911±63 K |
| Metallicity [Fe/H] | −0.20±0.05 dex |
| Rotational velocity (v sin i) | 87.7[9] km/s |
| Age | 1.74±0.15 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | ρ Cap |
| ρ Cap A | |
| ρ Cap B | |
| ARICNS | ρ Cap A |
| ρ Cap B | |
Rho Capricorni is a binary star[3] system in the constellation Capricornus. Its name is a Bayer designation that is Latinized from ρ Capricorni, and abbreviated Rho Cap or ρ Cap. Sometimes, this star is called by the name Bos, meaning the cow in Latin.[11] In Chinese, 牛宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of β Capricorni, α2 Capricorni, ξ2 Capricorni, π Capricorni, ο Capricorni and ρ Capricorni.[12] Consequently, the Chinese name for ρ Capricorni itself is 牛宿六 (Niú Su liù, English: the Sixth Star of Ox.)[13]
This system is visible to the naked eye with a combined apparent visual magnitude of +4.78.[2] The pair orbit each other with a period of 278 years and an eccentricity of 0.91.[3] Based upon an annual parallax shift of 33.23 mas as seen from the Earth,[1] the system is located about 98 light-years (30 pc) distant from the Sun. It is a thin disk population[7] 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).[14] Based upon its motion through space, this system may be a member of the Ursa Major moving group of stars.[5]
The primary member, component A, is a yellow-white hued, F-type subgiant with an apparent magnitude of 4.97[3] and a stellar classification of F2 IV.[2] This star has 1.5[7] times the mass of the Sun and 1.3 times the Sun's radius. It is radiating 9 times[8] as much luminosity of the Sun from its outer atmosphere at an effective temperature of 6,911 K.[7] The companion, component B, has a visual magnitude of 6.88.[3] The mass ratio is 0.539, meaning the secondary is only 53.9% as massive as the primary.[15]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940. Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 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.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, http://ad.usno.navy.mil/wds/orb6/orb6orbits.txt, retrieved 2017-05-12
- ↑ 4.0 4.1 Cvetkovic, Z.; Ninkovic, S. (June 2010), "On the Component Masses of Visual Binaries", Serbian Astronomical Journal 180 (180): 71–80, doi:10.2298/SAJ1080071C, Bibcode: 2010SerAJ.180...71C.
- ↑ 5.0 5.1 King, Jeremy R. et al. (April 2003), "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", The Astronomical Journal 125 (4): 1980–2017, doi:10.1086/368241, Bibcode: 2003AJ....125.1980K.
- ↑ 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.
- ↑ 7.0 7.1 7.2 7.3 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, doi:10.1088/0004-637X/756/1/46, Bibcode: 2012ApJ...756...46R.
- ↑ 8.0 8.1 McDonald, I. et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–357, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M.
- ↑ Schröder, C. et al. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics 493 (3): 1099–1107, doi:10.1051/0004-6361:200810377, Bibcode: 2009A&A...493.1099S
- ↑ "rho Cap". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=rho+Cap.
- ↑ "Bos", constellationsofwords.com, http://www.constellationsofwords.com/stars/Bos.html, retrieved 2017-05-12.
- ↑ Script error: The function "in_lang" does not exist. 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.
- ↑ Script error: The function "in_lang" does not exist. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 13 日
- ↑ Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics 575: 13, doi:10.1051/0004-6361/201425221, A35, Bibcode: 2015A&A...575A..35B.
- ↑ 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, doi:10.3847/1538-3881/ac2ee0, Bibcode: 2021AJ....162..260M.
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