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Epsilon Geminorum

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ε Geminorum
Location of ε Geminorum (circled)
Observation data
EpochJ2000EquinoxJ2000
Constellation Gemini
Right ascension 06h43m55.927s[1]
Declination +25° 07′ 52.06″[1]
Apparent magnitude(V) +3.06[2]
Characteristics
Spectral type G8 Ib[3]
U−Bcolor index +1.46[4]
B−Vcolor index +1.40[4]
Astrometry
Radial velocity(Rv)+8.09±0.14[5]km/s
Proper motion(μ)RA:−4.835mas/yr[1]
Dec.:−11.78mas/yr[1]
Parallax(π)3.748 ± 0.184mas[1]
Distance861+52
−39ly
(264+16
−12pc)[6]
Absolute magnitude(MV)−3.90[7]
Details
Mass5.29±0.04[8]– 8.33[9]M☉
Radius130.2+5.5
−6[8]R☉
Luminosity7,780[9]L☉
Surface gravity(logg)0.76[8]cgs
Temperature5009±63[8]K
Metallicity[Fe/H]0.15±0.07[10]dex
Rotational velocity(vsini)8.7±1.0[5]km/s
Age100[8]Myr
Other designations
Database references
SIMBADdata

Epsilon Geminorumorε Geminorum,formally namedMebsuta/mɛbˈsuːtə/,[11][12]is astarin theconstellationofGemini,on the outstretched right 'leg' of the twinCastor.Theapparent visual magnitudeof +3.06[2]makes it one of thebrighter starsin this constellation. The distance to this star is determined at 860light-years(260parsecs).[6]

Nomenclature[edit]

ε Geminorum(LatinisedtoEpsilon Geminorum) is the star'sBayer designation.It bore the traditional namesMebsuta,MelboulaorMelucta.Mebsutahas its roots in an ancientArabianview where it and the star Mekbuda (Zeta Geminorum) were the paws of a huge lion extending over many present-day constellations.[13]Mebsuta('Mabsūṭah' مبسوطة) comes from a phrase referring to the outstretched paw.[14]In 2016, theInternational Astronomical Unionorganized aWorking Group on Star Names(WGSN)[15]to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[16]included a table of the first two batches of names approved by the WGSN; which includedMebsutafor this star.

InChinese,Tỉnh túc(Jǐng Su), meaningWell(asterism),refers to an asterism consisting of ε Geminorum,μ Geminorum,ν Geminorum,γ Geminorum,ξ Geminorum,36 Geminorum,ζ Geminorumandλ Geminorum.[17]Consequently, ε Geminorum itself is known asTỉnh túc ngũ(Jǐng Su wǔ,English:the Fifth Star of Well.)[18]

Properties[edit]

Thespectrumof this star matches astellar classificationof G8 Ib,[3]where theluminosity classof Ib indicates this is a lower luminositysupergiant star.Alternatively, it may be a star that has passed through theasymptotic giant branchstage and possesses a detached shell of dust.[19]The estimated mass of this star is over 5.3 times the mass of the Sun, and, at an age of 100 million years, it has expanded to a 130 times the Sun's size.[8]Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[20]

Epsilon Geminorum is radiating around 9,640 times the luminosity of the Sun from its outer atmosphere at aneffective temperatureof5,000K.[8]It is this temperature that gives it the yellow-hued glow of aG-type star.[21]A surfacemagnetic fieldwith a strength of−0.14±0.19Ghas been detected on this star. This topologically complex field is most likely generated by a dynamo formed from the deepconvection zonein the star's outer envelope.[22]

It is located around 860light-yearsfrom Earth based on a photogeometric distance from Bailer-Joneset al(2021).[6]At this distance, theapparent magnitudeis diminished by 0.92magnitudesdue tointerstellar extinctionbetween Earth and the star.[8]

Occultations[edit]

Epsilon Geminorum lies near theecliptic,so it can beoccultedby theMoonor aplanet.Such an occultation took place on April 8, 1976 byMars,which allowed the oblateness of the planet's outer atmosphere to be measured.[23]Epsilon Geminorum was occulted byMercuryon June 10, 1940,[24]and on September 3, 2015 it was occulted by the asteroid112 Iphigenia.[25]

In culture[edit]

USS Melucta (AK-131)was aUnited States NavyCrater class cargo shipnamed after the star.

References[edit]

  1. ^abcdVallenari, A.; et al. (Gaia collaboration) (2023)."GaiaData Release 3. Summary of the content and survey properties ".Astronomy and Astrophysics.674:A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID244398875. Gaia DR3 record for this sourceatVizieR.
  2. ^abMallik, Sushma V. (December 1999), "Lithium abundance and mass",Astronomy and Astrophysics,352:495–507,Bibcode:1999A&A...352..495M
  3. ^abNordgren, Tyler E.; et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer",The Astronomical Journal,118(6): 3032–3038,Bibcode:1999AJ....118.3032N,doi:10.1086/301114
  4. ^abJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars",Communications of the Lunar and Planetary Laboratory,4(99): 99,Bibcode:1966CoLPL...4...99J
  5. ^abDe Medeiros, J. R.; et al. (November 2002), "A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars",Astronomy and Astrophysics,395:97–98,Bibcode:2002A&A...395...97D,doi:10.1051/0004-6361:20021214
  6. ^abcBailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Demleitner, M.; Andrae, R. (2021-03-01), "Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3",The Astronomical Journal,161(3): 147,arXiv:2012.05220,Bibcode:2021AJ....161..147B,doi:10.3847/1538-3881/abd806,ISSN0004-6256Data about this star can be seenhere.
  7. ^Park, Sunkyung; Kang, Wonseok; Lee, Jeong-Eun; Lee, Sang-Gak (2013), "Wilson-Bappu Effect: Extended to Surface Gravity",The Astronomical Journal,146(4): 73,arXiv:1307.0592,Bibcode:2013AJ....146...73P,doi:10.1088/0004-6256/146/4/73,S2CID119187733
  8. ^abcdefghBaines, Ellyn K.; Armstrong, J. Thomas; Schmitt, Henrique R.; Zavala, R. T.; Benson, James A.; Hutter, Donald J.; Tycner, Christopher; Belle, Gerard T. van (2017-12-21), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer",The Astronomical Journal,155(1): 30,arXiv:1712.08109,doi:10.3847/1538-3881/aa9d8b,ISSN0004-6256
  9. ^abAyres, Thomas (2023-05-01)."In the Trenches of the Solar-Stellar Connection. VII. Wilson-Bappu 2022".The Astrophysical Journal Supplement Series.266(1): 6.Bibcode:2023ApJS..266....6A.doi:10.3847/1538-4365/acb535.ISSN0067-0049.Epsilon Geminorum's database entryatVizieR.
  10. ^Wu, Yue; et al. (January 2011), "Coudé-feed stellar spectral library - atmospheric parameters",Astronomy and Astrophysics,525:A71,arXiv:1009.1491,Bibcode:2011A&A...525A..71W,doi:10.1051/0004-6361/201015014,S2CID53480665
  11. ^Davis, George A. (1944), "The pronunciations, derivations, and meanings of a selected list of star names",Popular Astronomy,52:8–30,Bibcode:1944PA.....52....8D
  12. ^IAU Catalog of Star Names,retrieved28 July2016
  13. ^Allen, Richard Hinckley(1899),Star-names and their meanings,G. E. Stechert, p. 231See alsopage 97.
  14. ^Allen, Richard Hinckley(1899),Star-names and their meanings,G. E. Stechert, p. 235
  15. ^"IAU Working Group on Star Names (WGSN)".Retrieved22 May2016.
  16. ^"Bulletin of the IAU Working Group on Star Names, No. 1"(PDF).Retrieved28 July2016.
  17. ^(in Chinese)Trung quốc tinh tọa thần thoại,written by trần cửu kim. Published by đài loan thư phòng xuất bản hữu hạn công tư, 2005,ISBN978-986-7332-25-7.
  18. ^(in Chinese)Hương cảng thái không quán - nghiên cứu tư nguyên - lượng tinh trung anh đối chiếu biểuArchivedJanuary 30, 2011, at theWayback Machine,Hong Kong Space Museum. Accessed on line November 23, 2010.
  19. ^Lobel, A.; Dupree, A. K. (December 2000), "The Chromospheres of G-type Ib Supergiants",Bulletin of the American Astronomical Society,32:1474,Bibcode:2000AAS...197.4415L
  20. ^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 fromthe originalon 2019-06-25,retrieved2012-02-04
  21. ^"The Colour of Stars",Australia Telescope, Outreach and Education,Commonwealth Scientific and Industrial Research Organisation,December 21, 2004, archived fromthe originalon 2012-03-18,retrieved2012-01-16
  22. ^Grunhut, J. H.; et al. (November 2010), "Systematic detection of magnetic fields in massive, late-type supergiants",Monthly Notices of the Royal Astronomical Society,408(4): 2290–2297,arXiv:1006.5891,Bibcode:2010MNRAS.408.2290G,doi:10.1111/j.1365-2966.2010.17275.x,S2CID118564860
  23. ^French, R. G.; Taylor, G. E. (March 1981), "Occultation of Epsilon Geminorum by Mars. IV - Oblateness of the Martian upper atmosphere",Icarus,45(3): 577–585,Bibcode:1981Icar...45..577F,doi:10.1016/0019-1035(81)90023-3
  24. ^Können, G. P.; Van Maanen, J. (1981), "Planetary occultations of bright stars",Journal of the British Astronomical Association,91:148–157,Bibcode:1981JBAA...91..148K
  25. ^Steve's Asteroid Occultations,archived fromthe originalon 2015-09-23,retrieved2015-03-20
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