Astronomy:Chi Geminorum
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Gemini[1] |
| Right ascension | 08h 03m 31.08225s[2] |
| Declination | +27° 47′ 39.6243″[2] |
| Apparent magnitude (V) | 4.98[3] |
| Characteristics | |
| Evolutionary stage | red giant branch[4] |
| Spectral type | K2 III[5] |
| U−B color index | +1.09[3] |
| B−V color index | +1.14[3] |
| Astrometry | |
| Radial velocity (Rv) | −3.83±0.17[6] km/s |
| Proper motion (μ) | RA: −25.52[2] mas/yr Dec.: −31.89[2] mas/yr |
| Parallax (π) | 12.73 ± 0.90[2] mas |
| Distance | 260 ± 20 ly (79 ± 6 pc) |
| Absolute magnitude (MV) | 0.461[7] |
| Orbit[8] | |
| 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[6] | |
| Mass | 1.83[5] 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[5] 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.[3] Based upon an annual parallax shift of 12.73 mas,[2] 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.[8] The primary component is a K-type giant star with a stellar classification of K2 III.[5] This is a candidate mild Barium star with the slight overabundance most likely acquired through accretion from what is now a white dwarf companion.[10] The primary has an estimated 1.83[5] times the mass of the Sun and has expanded to 14 times the Sun's radius.[6] The effective temperature of the outer atmosphere is 4,560 K, from whence it radiates 79 times the solar luminosity.[6] It has a leisurely projected rotational velocity of 3.8 km/s[6] and is around two billion years old.[5]
References
- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R. Constellation record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 3.0 3.1 3.2 3.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal 150 (3): 23, doi:10.1088/0004-6256/150/3/88, 88, Bibcode: 2015AJ....150...88L.
- ↑ 6.0 6.1 6.2 6.3 6.4 Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M.
- ↑ Soubiran, C. et al. (March 2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S.
- ↑ 8.0 8.1 Pourbaix, D. et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics 424 (2): 727–732, doi:10.1051/0004-6361:20041213, Bibcode: 2004A&A...424..727P.
- ↑ "* chi Gem". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+chi+Gem.
- ↑ Yang, Guo-Chao et al. (January 2016), "Chemical abundance analysis of 19 barium stars", Research in Astronomy and Astrophysics 16 (1): 019, doi:10.1088/1674-4527/16/1/019, 19, Bibcode: 2016RAA....16...19Y.
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