Eta Capricorni

Eta Capricorni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Capricornus
Right ascension 21h 04m 24.30132s[1]
Declination −19° 51′ 17.9711″[1]
Apparent magnitude (V) +4.84[2] (5.02 + 7.39)[3]
Characteristics
Spectral type A4 V + F2 V[4]
U−B color index +0.09[2]
B−V color index +0.17[2]
Astrometry
Proper motion (μ) RA: −37.62±0.90[1] mas/yr
Dec.: −24.95±0.88[1] mas/yr
Parallax (π)20.20 ± 0.82 mas[1]
Distance161 ± 7 ly
(50 ± 2 pc)
Absolute magnitude (MV)+1.35[5]
Orbit[6]
Period (P)27.85±0.15 yr
Semi-major axis (a)0.265±0.003″
Eccentricity (e)0.410±0.005
Inclination (i)162.6±0.5°
Longitude of the node (Ω)171.1±15.0°
Periastron epoch (T)2002.46±0.09
Argument of periastron (ω)
(secondary)		238.2±15.0°
Details
η Cap A
Mass2.03±0.12[6] M☉
Luminosity24[5] L☉
Metallicity [Fe/H]−0.01[5] dex
η Cap B
Mass1.21±0.07[6] M☉
Other designations
η Cap, 22 Cap, BD−20° 6115, HD 200499, HIP 104019, HR 8060, SAO 189986, WDS J21044-1951AB[7]
Database references
SIMBADdata

Eta Capricorni, Latinized from η Capricorni, is a binary star[6] system in the southern constellation of Capricornus. It can be seen with the naked eye, having a combined apparent visual magnitude of +4.84.[2] Based upon an annual parallax shift of 20.20 mas as seen from the Earth,[1] the star is located about 161 light years from the Sun.

The pair orbit each other with a period of 27.85 years, a semimajor axis of 0.265 arc seconds, an eccentricity of 0.410.[6] The primary member, component A, is a white-hued A-type main sequence star with an apparent magnitude of +5.02.[3] Its companion, component B, has an apparent magnitude of +7.39.[3]

  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 Cite error: The named reference Nicolet1978 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference tenBrummelaar2000 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference Docobo2013 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).