Rho Capricorni
Star in the constellation Capricornus
From Wikipedia, the free encyclopedia
Rho Capricorni is a binary star[3] system in the constellation Capricornus. Its name is a Bayer designation that is Latinized from Ï Capricorni, and abbreviated Rho Cap or Ï Cap. Sometimes, this star is called by the name Bos, meaning the cow in Latin.[11] In Chinese, ç宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of β Capricorni, α2 Capricorni, ξ2 Capricorni, Ï Capricorni, ο Capricorni and Ï Capricorni.[12] Consequently, the Chinese name for Ï Capricorni itself is ç宿å (Niú Su liù, English: the Sixth Star of Ox.)[13]
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 20h 28m 51.615s[1] |
| Declination | â17° 48â² 49.26â³[1] |
| Apparent magnitude (V) | +4.78[2] (4.97 + 6.88)[3] |
| Characteristics | |
| Spectral type | F2 IV[2] + G1[4] |
| BâV color index | 0.340/0.635[5] |
| Astrometry | |
| Radial velocity (Rv) | +18.4[6] km/s |
| Proper motion (μ) | RA: â16.889 mas/yr[1] Dec.: â10.579 mas/yr[1] |
| Parallax (Ï) | 33.2297±0.2146 mas[1] |
| 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) | 1.877â³ |
| Eccentricity (e) | 0.91 |
| Inclination (i) | 113.3° |
| Longitude of the node (Ω) | 162.0° |
| Periastron epoch (T) | 1965.0 |
| Argument of periastron (Ï) (secondary) | 144.5° |
| Details[7] | |
| Ï Cap A | |
| Mass | 1.52±0.04 Mâ |
| Radius | 1.3[2] Râ |
| Luminosity | 9[8] Lâ |
| Surface gravity (log g) | 4.02±0.03 cgs |
| Temperature | 6,911±63 K |
| Metallicity [Fe/H] | â0.20±0.05 dex |
| Rotational velocity (v sin i) | 87.7[9] km/s |
| Age | 1.74±0.15 Gyr |
| Other designations | |
| Ï Cap, 11 Cap, BDâ18°5689, GJ 791.1, GJ 9696, HD 194943, HIP 101027, HR 7822, SAO 163614, ADS 13887, WDS J20289-1749AB[10] | |
| Database references | |
| SIMBAD | Ï Cap |
| Ï Cap A | |
| Ï Cap B | |
| ARICNS | Ï Cap A |
| Ï Cap B | |
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]