Kappa Geminorum

Kappa Geminorum (κ Geminorum, κ Gem) is a binary star system in the northern zodiac constellation of Gemini. It is visible to the naked eye with an apparent visual magnitude of 3.568.^[2] Based upon an annual parallax shift of 23.07 mas,^[1] the system is located about 141 light years distant from the Sun.

κ Geminorum

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Gemini
Right ascension	07h 44m 26.85357s[1]
Declination	+24° 23′ 52.7872″[1]
Apparent magnitude (V)	3.568[2] + 8.2[3]
Characteristics
Spectral type	G9 III[4]
U−B color index	+0.700[2]
B−V color index	+0.941[2]
Astrometry
Radial velocity (Rv)	20.6[5] km/s
Proper motion (μ)	RA: −23.39[1] mas/yr Dec.: −54.57[1] mas/yr
Parallax (π)	23.07 ± 0.22 mas[1]
Distance	141 ± 1 ly (43.3 ± 0.4 pc)
Absolute magnitude (MV)	+0.35[6]
Details
Mass	2.07[7] M☉
Radius	11.00±0.16[8] R☉
Luminosity	69.3±3.7[8] L☉
Surface gravity (log g)	2.8[9] cgs
Temperature	5,020±68[8] K
Metallicity [Fe/H]	−0.16[9] dex
Rotational velocity (v sin i)	3.3[9] km/s
Age	2.07[7] Gyr
Other designations
κ Gem, 77 Geminorum, BD+24° 1759, FK5 294, HD 62345, HIP 37740, HR 2985, SAO 79653.[10]
Database references
SIMBAD	data

In Chinese astronomy, Kappa Geminorum is called 積薪, Pinyin: Jīxīn, meaning Pile of Firewood, because this star is marking itself and stand alone in Pile of Firewood asterism, Well mansion (see : Chinese constellation).^[11] 積薪 (Jīxīn) westernized into Tseih Tsing, but the name Tseih Tsing was designated for χ Gem and μ Cnc by R.H. Allen, with the meaning is "piled-up fuel"^[12] In Japanese, 隆博星 (Takahiro-boshi), meaning "Esteemed Nobility Star," refers to the Japanese description of κ Geminorum.

This is a probable astrometric binary^[3] system with the components having an angular separation of 7.2 arcseconds along a position angle of 241°, as of 2014.^[13] The primary is an evolved G-type giant star with a stellar classification of G9 III.^[4] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.^[14] It has double the mass of the Sun,^[7] but has expanded to 11 times the solar radius. The star radiates around 69 times the Sun's luminosity from its outer atmosphere at an effective temperature of 5,020 K.^[8] It shows a leisurely spin with a projected rotational velocity of 3.3 km/s, and is around two billion years old.^[7] The secondary component is a magnitude 8.2 star.^[3]

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
2. Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172 (3): 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
3. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
4. Abt, Helmut A. (2008). "Visual Multiples. IX. MK Spectral Types". The Astrophysical Journal Supplement Series. 176 (1): 216–217. Bibcode:2008ApJS..176..216A. doi:10.1086/525529.
5. Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
6. Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440, S2CID 12136256.
7. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
8. Baines, Ellyn K.; Armstrong, J. Thomas; Schmitt, Henrique R.; Zavala, R. T.; Benson, James A.; Hutter, Donald J.; Tycner, Christopher; Van Belle, Gerard T. (2018), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155 (1): 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b, S2CID 119427037.
9. 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, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
10. "kap Gem -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-05.
11. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 16 日 Archived 2011-08-22 at the Wayback Machine
12. Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Gemini.
13. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
14. Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society, 25: 1319, Bibcode:1993AAS...183.1710G, archived from the original on 2019-06-25, retrieved 2012-02-04.

External links

• Kaler, James B. (November 2, 2011), "Kappa Geminorum", Stars, University of Illinois, retrieved 2016-12-06.