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| 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] |
| Distance | 260 ± 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] | |
| Mass | 1.83[3] M☉ |
| Radius | 14 R☉ |
| Luminosity | 79 L☉ |
| Surface gravity (log g) | 2.5 cgs |
| Temperature | 4,560±5 K |
| Metallicity [Fe/H] | 0.03 dex |
| Rotational velocity (v sin i) | 3.8 km/s |
| Age | 1.92[3] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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]
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