Astronomy:Iota Geminorum

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Short description: G-type star in the constellation Gemini
ι Geminorum
Location of ι Geminorum (circled in red)
Observation data
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
Evolutionary stage Red-giant branch[3]
Spectral type G9 III[4]
U−B color index +0.88[2]
B−V color index +1.01[2]
Astrometry
Radial velocity (Rv)7.26±0.16[5] km/s
Proper motion (μ) RA: −122.66[1] mas/yr
Dec.: −84.03[1] mas/yr
Parallax (π)27.10 ± 0.20[1] mas
Distance120.4 ± 0.9 ly
(36.9 ± 0.3 pc)
Absolute magnitude (MV)+0.859[6]
Details
Mass1.89[7] M☉
Radius9.48±0.12[8] R☉
Luminosity53.7±2.8[8] L☉
Surface gravity (log g)2.8[5] cgs
Temperature5,072±68[8] K
Metallicity [Fe/H]−0.17[5] dex
Rotational velocity (v sin i)0.0[5] km/s
Age4.16±2.54[6] Gyr
Other designations
ι Gem, 60 Gem, BD+28°1385, FK5 282, HD 58207, HIP 36046, HR 2821, SAO 79374[9]
Database references
SIMBADdata

Iota Geminorum (ι Geminorum, ι Gem) is a solitary[10] 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.[11]

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.[12] Consequently, ι Geminorum itself is known as 五諸侯三 (Wu Zhū Hóu sān, English: the Third Star of Five Feudal Kings).[13] It has been called by the proper name Propus, meaning "forefoot" in Latin,[14] but this name is more correctly assigned to η Geminorum.[15]

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-giant branch[3] giant star with a stellar classification of G9 III.[4] It is most likely a member of the galactic thin disk population.[6] The star has 1.89[7] times the mass of the Sun, but has expanded to 9.5 times the solar radius. It shines with 54 times the Sun's luminosity from its outer atmosphere at an effective temperature of 5,072 K.[8]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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. 
  2. ↑ 2.0 2.1 2.2 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, doi:10.1093/mnras/172.3.667, Bibcode: 1975MNRAS.172..667J. 
  3. ↑ 3.0 3.1 Bale, B.; Tautvaišienė, G.; Minkevičiūtė, R.; Drazdauskas, A.; Mikolaitis, Š; Stonkutė, E.; Ambrosch, M. (2025-11-01), "Chromospherically active stars: Lithium and CNO abundances in northern RS CVn stars" (in en), Astronomy & Astrophysics 703: A128, doi:10.1051/0004-6361/202556683, ISSN 0004-6361 .
  4. ↑ 4.0 4.1 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics 11: 29, doi:10.1146/annurev.aa.11.090173.000333, Bibcode: 1973ARA&A..11...29M. 
  5. ↑ 5.0 5.1 5.2 5.3 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. 
  6. ↑ 6.0 6.1 6.2 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. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ 8.0 8.1 8.2 8.3 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, doi:10.3847/1538-3881/aa9d8b, Bibcode: 2018AJ....155...30B. 
  9. ↑ "iot Gem". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=iot+Gem. 
  10. ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  11. ↑ O'Meara, Steve (2007), Herschel 400 Observing Guide, Cambridge University Press, p. 76, ISBN 978-0521858939, https://books.google.com/books?id=Nyh9fAC_tpIC&pg=PA76. 
  12. ↑ 陳久金 (2005) (in zh). 中國星座神話. 五南圖書出版股份有限公司. ISBN 978-986-7332-25-7. https://books.google.com/books?id=0Vex0rYzdu8C. 
  13. ↑ "研究資源 - 亮星中英對照表" (in zh). 香港太空館. http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_n_r.htm. 
  14. ↑ Allen, R. H. (1899), Star Names: Their Lore and Meaning, p. 236, https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Gemini*.html 
  15. ↑ "Naming stars". IAU. https://www.iau.org/public/themes/naming_stars/. 



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