Rho Capricorni

Rho Capricorni
Location of ρ Capricorni (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Capricornus
Right ascension 20h 28m 51.61448s[1]
Declination −17° 48′ 49.2693″[1]
Apparent magnitude (V) +4.78[2] (4.97 + 6.88)[3]
Characteristics
Spectral type F2 IV[2] + G1[4]
Astrometry
Radial velocity (Rv)+18.4[5] km/s
Proper motion (μ) RA: −14.98[1] mas/yr
Dec.: −7.29[1] mas/yr
Parallax (π)33.04 ± 0.46 mas[1]
Distance99 ± 1 ly
(30.3 ± 0.4 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[6]
ρ Cap A
Mass1.52±0.04 M☉
Radius1.3[2] R☉
Luminosity9[7] L☉
Surface gravity (log g)4.02±0.03 cgs
Temperature6,911±63 K
Metallicity [Fe/H]−0.20±0.05 dex
Rotational velocity (v sin i)87.7[8] km/s
Age1.74±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[9]
Database references
SIMBADρ Cap
ρ Cap A
ρ Cap B
ARICNSρ Cap A
ρ Cap B

Rho Capricorni (ρ Cap, ρ Capricorni) is a binary star[3] in the constellation Capricornus. Sometimes, this star is called by the name Bos, meaning the cow in Latin.[10] 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.[11] Consequently, the Chinese name for ρ Capricorni itself is 牛宿六 (Niú Su liù, English: the Sixth Star of Ox.)[12]

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 33.04 mas as seen from the Earth,[1] the system is located about 99 light years from the Sun. It is a thin disk population[6] 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).[13]

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[6] times the mass of the Sun and 1.3 times the Sun's radius. It is radiating 9 times[7] as much luminosity of the Sun from its outer atmosphere at an effective temperature of 6,911 K.[6] 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.[14]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference aass85_3_1015 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference orb6 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Cvetkovic2010 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Ramirez2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference McDonald2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Schroeder2009 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference CoW was invoked but never defined (see the help page).
  11. ^ (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.
  12. ^ (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
  13. ^ Cite error: The named reference aa575_A35 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Makarov was invoked but never defined (see the help page).