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[1] mas
Distance141 ± 1 ly
(43.3 ± 0.4 pc)
Absolute magnitude (MV)+0.35[6]
Details[7]
Mass2.07[8] M☉
Radius11 R☉
Luminosity67.6 L☉
Surface gravity (log g)2.8 cgs
Temperature4,932±15 K
Metallicity [Fe/H]−0.16 dex
Rotational velocity (v sin i)3.3 km/s
Age2.07[8] Gyr
Other designations
κ Gem, 77 Geminorum, BD+24° 1759, FK5 294, HD 62345, HIP 37740, HR 2985, SAO 79653.[9]
Database references
SIMBADdata

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).[10] 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"[11] 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.[12] 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.[13] It has double the mass of the Sun,[8] but has expanded to 11 times the solar radius. The star radiates around 68 times the Sun's luminosity from its outer atmosphere at an effective temperature of 4,932 K. It shows a leisurely spin with a projected rotational velocity of 3.3 km/s, and is around two billion years old.[8] 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. 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.
  8. 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.
  9. "kap Gem -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-05.
  10. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 16 日
  11. Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Gemini.
  12. 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.
  13. 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, retrieved 2012-02-04.
  • Kaler, James B. (November 2, 2011), "Kappa Geminorum", Stars, University of Illinois, retrieved 2016-12-06.
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