Chi Geminorum

χ Geminorum
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Gemini
Right ascension 08h 03m 31.08225s[1]
Declination +27° 47′ 39.6243″[1]
Apparent magnitude (V) 4.98[2]
Characteristics
Spectral type K2 III[3]
U−B color index +1.09[2]
B−V color index +1.14[2]
Astrometry
Radial velocity (Rv)−3.83±0.17[4] km/s
Proper motion (μ) RA: −25.52[1] mas/yr
Dec.: -31.89[1] mas/yr
Parallax (π)12.73 ± 0.90 mas[1]
Distance260 ± 20 ly
(79 ± 6 pc)
Absolute magnitude (MV)0.461[5]
Orbit[6]
Period (P)2,437.8d
Eccentricity (e)0.06
Periastron epoch (T)2442894.5 ± 10.0 JD
Argument of periastron (ω)
(secondary)		264°
Semi-amplitude (K1)
(primary)		5.2 km/s
Details[4]
Mass1.83[3] M☉
Radius14 R☉
Luminosity79 L☉
Surface gravity (log g)2.5 cgs
Temperature4,560±5 K
Metallicity [Fe/H]0.03 dex
Rotational velocity (v sin i)3.8 km/s
Age1.92[3] Gyr
Other designations
χ Gem, BD+28° 1532, FK5 305, HD 66216, HIP 39424, HR 3149, SAO 79896.[7]
Database references
SIMBADdata

Chi Geminorum (χ Gem) is a binary star system in the constellation Gemini, near the eastern border with Cancer. It can be viewed with the naked eye on a dark night, having an apparent visual magnitude of 4.98.[2] Based upon an annual parallax shift of 12.73 mas,[1] it is located roughly 260 light years from the Sun.

The two components of this system form a spectroscopic binary with an orbital period of 2,437.8 days and an eccentricity of 0.06.[6] The primary component is a K-type giant star with a stellar classification of K2 III.[3] This is a candidate mild Barium star with the slight overabundance most likely acquired through accretion from what is now a white dwarf companion.[8] The primary has an estimated 1.83[3] times the mass of the Sun and has expanded to 14 times the Sun's radius.[4] The effective temperature of the outer atmosphere is 4,560 K, from whence it radiates 79 times the solar luminosity.[4] It has a leisurely projected rotational velocity of 3.8[4] km/s and is around two billion years old.[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 Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference Massarotti2008 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Soubiran2008 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Pourbaix2004 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).
  8. ^ Cite error: The named reference Yang2016 was invoked but never defined (see the help page).