Mu Geminorum

μ Geminorum


Location of μ Geminorum (circled)

Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Gemini
Right ascension 06h 22m 57.62686s[1]
Declination +22° 30′ 48.8979″[1]
Apparent magnitude (V) 2.857[2]
Characteristics
Spectral type M3 III[3]
B−V color index +1.643[2]
Variable type LB[4]
Astrometry
Radial velocity (Rv)+54.38 ± 0.24[5] km/s
Proper motion (μ) RA: +56.39[1] mas/yr
Dec.: –110.03[1] mas/yr
Parallax (π)14.08 ± 0.71[1] mas
Distance230 ± 10 ly
(71 ± 4 pc)
Absolute magnitude (MV)−1.42[6]
Details
Mass2.1[7] M☉
Luminosity2,799[8] L☉
Surface gravity (log g)1.50[8] cgs
Temperature3,773[8] K
Rotational velocity (v sin i)8.4[9] km/s
Other designations
Tejat, Tejat Posterior, Pish Pai, Calx,[10][11] μ Geminorum, μ Gem, 13 Geminorum, 13 Gem, ADS 4990A, BD+22°1304, CCDM J06230+2230A, FK5 241, HD 44478, HIP 30343, HR 2286, SAO 78297.[12]
Database references
SIMBADdata

Mu Geminorum (μ Gem, μ Geminorum), also named Tejat,[13] is a star in the northern constellation of Gemini.

Nomenclature

μ Geminorum (Latinised to Mu Geminorum) is the system's Bayer designation.

It bore the traditional name Tejat, or Tejat Posterior, which means back foot, because it is the foot of Castor, one of the Gemini twins. The proper name Tejat Posterior was formerly applied to an asterism consisting of this star, along with γ Gem (Alhena), ν Gem, η Gem (Tejat Prior), and ξ Gem (Alzirr). The names Calx (Latin, meaning heel), Pish Pai (from the Persian Pīshpāy, پیش‌پای, meaning foreleg), and Nuhatai (from Arabic Al Nuḥātai, the dual form of Al Nuḥāt, "a Camel's Hump") have also been applied to Mu Geminorum.[10][11]  In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[14] to catalogue and standardize proper names for stars. The WGSN approved the name Tejat for this star on February 1st 2017 and it is now so entered in the IAU Catalog of Star Names.[13]

In Chinese, 井宿 (Jǐng Su), meaning Well (asterism), refers to an asterism consisting of μ Geminorum, γ Geminorum, ν Geminorum, ξ Geminorum, ε Geminorum, 36 Geminorum, ζ Geminorum and λ Geminorum.[15] Consequently, μ Geminorum itself is known as 井宿一 (Jǐng Su yī, English: the First Star of Well.)[16]

Properties

μ Gem is the star on the left, surrounded by the S249 nebula. The bright star on the right, near the IC 443 supernova remnant, is η Gem.

Mu Geminorum has an average apparent visual magnitude of 2.9,[2] which makes it the fourth-brightest member of Gemini. Because the star lies near the ecliptic it is subject to occultations by the Moon.[17] From parallax measurements made during the Hipparcos mission, the distance to this star is roughly 230 light-years (71 parsecs).[1] Its visual magnitude is diminished by 0.07 as a result of extinction from intervening gas and dust.[5]

This star is a slow irregular variable of type LB. Its brightness varies between magnitude +2.75 and +3.02 over a 72-day period, along with a 2,000-day period of long term variation. It is a red giant at a stellar classification of M3 III,[3] with a surface temperature of 3,773 K,[8] meaning it is brighter, yet cooler, than the Sun.[4][10] The star is currently on the asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen.[18]

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752 Freely accessible, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G.
  3. 1 2 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. 1 2 mu Gem, entry in the Combined General Catalog of Variable Stars (GCVS4.2), N. N. Samus, O. V. Durlevich, et al., database identifier II/250 at the Centre de Données astronomiques de Strasbourg.
  5. 1 2 Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, Bibcode:2005A&A...430..165F, arXiv:astro-ph/0409579 Freely accessible, doi:10.1051/0004-6361:20041272.
  6. ↑ Schiavon, Ricardo P. (July 2007), "Population Synthesis in the Blue. IV. Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations", The Astrophysical Journal Supplement Series, 171 (1): 146–205, Bibcode:2007ApJS..171..146S, arXiv:astro-ph/0611464 Freely accessible, doi:10.1086/511753.
  7. ↑ Tsuji, Takashi (May 2007), "Isotopic abundances of Carbon and Oxygen in Oxygen-rich giant stars", in Kupka, F.; Roxburgh, I.; Chan, K., Convection in Astrophysics, Proceedings of IAU Symposium #239 held 21-25 August, 2006 in Prague, Czech Republic, pp. 307–310, Bibcode:2007IAUS..239..307T, arXiv:astro-ph/0610180 Freely accessible, doi:10.1017/S1743921307000622.
  8. 1 2 3 4 Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&A...352..495M.
  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. 1 2 3 "Tejat". Jim Kaler's STARS. Retrieved 2017-03-31.
  11. 1 2 Allen, Richard Hinckley (1899), Star-names and Their Meanings, G. E. Stechert, p. 236
  12. ↑ "mu. Gem -- Pulsating variable Star", Simbad Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved October 12, 2007.
  13. 1 2 "IAU-CSN".
  14. ↑ "International Astronomical Union | IAU". www.iau.org. Retrieved 2017-04-01.
  15. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  16. ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  17. ↑ White, Nathaniel M.; Feierman, Barry H. (September 1987), "A Catalog of Stellar Angular Diameters Measured by Lunar Occultation", Astronomical Journal, 94: 751, Bibcode:1987AJ.....94..751W, doi:10.1086/114513.
  18. ↑ Lebzelter, T.; Hron, J. (January 2008), "BRITE stars on the AGB", Communications in Asteroseismology, 152: 178–181, Bibcode:2008CoAst.152..178L, doi:10.1553/cia152s178.

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