Iota Geminorum

Iota Geminorum (ι Geminorum, ι Gem) is a solitary[8] fourth-magnitude star in the constellation Gemini. In the sky, it forms an isosceles triangle with Castor and Pollux, and is located less than a degree from the 5th magnitude stars 64 and 65 Geminorum.[9]

ι Geminorum
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Gemini
Right ascension 07h 25m 43.59532s[1]
Declination +27° 47′ 53.0929″[1]
Apparent magnitude (V) 3.791[2]
Characteristics
Spectral type G9 III[3]
U−B color index +0.88[2]
B−V color index +1.01[2]
Astrometry
Radial velocity (Rv)7.26±0.16[4] km/s
Proper motion (μ) RA: −122.66[1] mas/yr
Dec.: −84.03[1] mas/yr
Parallax (π)27.10 ± 0.20 mas[1]
Distance120.4 ± 0.9 ly
(36.9 ± 0.3 pc)
Absolute magnitude (MV)+0.859[5]
Details[4]
Mass1.89[6] M☉
Radius10 R☉
Luminosity48 L☉
Surface gravity (log g)2.8 cgs
Temperature4,753 K
Metallicity [Fe/H]−0.17 dex
Rotational velocity (v sin i)0.0 km/s
Age4.16±2.54[5] Gyr
Other designations
ι Gem, 60 Geminorum, BD+28° 1385, FK5 282, HD 58207, HIP 36046, HR 2821, SAO 79374.[7]
Database references
SIMBADdata

Nomenclature

In Chinese, 五諸侯 (Wu Zhū Hóu), meaning Five Feudal Kings, refers to an asterism consisting of ι Geminorum, θ Geminorum, τ Geminorum, υ Geminorum and φ Geminorum.[10] Consequently, ι Geminorum itself is known as 五諸侯三 (Wu Zhū Hóu sān, English: the Third Star of Five Feudal Kings.).[11] It has been called by the proper name Propus, meaning "forefoot" in Latin, but this name is now assigned to η Geminorum.[12]

Properties

Based upon an annual parallax shift of 27.10 mass,[1] Iota Geminorum lies some 120.4 light years from the Sun. This is an evolved red clump[13] giant star with a stellar classification of G9 III.[3] It is most likely a member of the galactic thin disk population.[5] The star has 1.89[6] times the mass of the Sun, but has expanded to 10 times the solar radius. It shines with 48[4] times the Sun's luminosity from its outer atmosphere at an effective temperature of 4,753 K.[4]

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. Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
  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, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
  5. 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, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788, S2CID 16602121.
  6. Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
  7. "iot Gem". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-12-04.{{cite web}}: CS1 maint: postscript (link)
  8. Eggleton, P. P.; Tokovinin, A. A. (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.
  9. O'Meara, Steve (2007), Herschel 400 Observing Guide, Cambridge University Press, p. 76, ISBN 978-0521858939.
  10. 陳久金 (2005). 中國星座神話 [Chinese horoscope mythology] (in Chinese). 五南圖書出版股份有限公司. ISBN 978-986-7332-25-7.
  11. "研究資源 - 亮星中英對照表" [Bright Star Sino-British comparison table] (in Chinese). 香港太空館. Archived from the original on 2011-01-30. Retrieved 2018-01-08.
  12. "Naming stars". IAU. Retrieved 2018-11-29.
  13. Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society, 408 (2): 1225–1232, arXiv:1006.3857, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x, S2CID 44228180.
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