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WY Geminorum

From Wikipedia, the free encyclopedia
Binary star in the constellation Gemini
WY Geminorum

Avisual bandlight curve for WY Geminorum, plotted fromASAS-SN data[1]
Observation data
Epoch J2000.0      Equinox J2000.0
ConstellationGemini[2]
Right ascension06h 11m 56.250s[3]
Declination+23° 12′ 25.41″[3]
Apparent magnitude (V)7.263 to 7.513[4]
Characteristics
Spectral typeM2Ia-b + B2V[5]
B−Vcolor index1.517±0.017[2]
Variable typeIrregular variable +eclipsing binary[6]
Astrometry
Radial velocity (Rv)19.52±0.22[7] km/s
Proper motion (μ)RA: 0.450mas/yr[3]
Dec.: −2.380mas/yr[3]
Parallax (π)0.5169±0.0343 mas[3]
Distance6,300 ± 400 ly
(1,900 ± 100 pc)
Orbit[5]
Period (P)64.48 ± 0.68 yr
Semi-major axis (a)≥ (4.09±0.19)×109 km
Eccentricity (e)0.61±0.03
Periastronepoch (T)2,445,620±130 JD
Argument of periastron (ω)
(secondary)		57.5±4.5°
Semi-amplitude (K1)
(primary)		16.0±0.9 km/s
Details
Primary
Radius522+45
−34[8] R☉
Surface gravity (log g)0.70[9] cgs
Temperature3,789[9] K
Metallicity [Fe/H]−0.36[9] dex
Other designations
WY Gem,BD+23° 1243,HD 42474,HIP 29425,SAO 78094,PPM 95591[10]
Database references
SIMBADdata

WY Geminorum is abinary star system in the northernconstellation ofGemini, abbreviated WY Gem. It has anapparent visual magnitude that ranges from 7.26 down to 7.51,[4] which is too faint to be readily viewed with thenaked eye. This system is located at a distance of approximately 6,300 light years from the Sun based onparallax measurements, and is receding with aradial velocity of 19.5 km/s.[7]

In 1922,M. L. Humason found thespectrum of HD 42474 matches anM-type star, but with the peculiarity of numerous brightlines. It appears similar to the spectrum ofVV Cephei (HR 8383), an eclipsing binary.[11]P. Swings andO. Struve in 1941 discoveredemission lines in theultraviolet spectrum.[12] The presence of aB-type stellar spectrum from a companion star was confirmed byW. P. Bidelman in 1954. The primary spectrum matches an M-typesupergiant star.[13]A. Cowley in 1970 found evidence of an atmospheric eclipse of the companion.[14] In 1981,A. Buzzoni determined the primary to be asemi-regular variable of the SRb type with a period of 169 days.[15]

This is a double-linedspectroscopic binary star system with an approximateorbital period of 64.48 ± 0.68 years and a higheccentricity (ovalness) of 0.61. The primary component is an M-type supergiant star with astellar classification of M2Ia or b. The companion is most likely a hotterB-type main-sequence star with a class of B2V.[5] The pair are classified as a VV Cephei-type star system. The companion may be accreting matter from the supergiant around the time ofperiastron passage, resulting in the formation of an intermittentaccretion disk orbiting the hotter star.[5]Radio emission has been detected, which is most likely coming from an ionized region in thestellar wind of the supergiant.[16]

References

[edit]
  1. ^"ASAS-SN Variable Stars Database".ASAS-SN Variable Stars Database. ASAS-SN. Retrieved21 June 2024.
  2. ^abAnderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation",Astronomy Letters,38 (5): 331,arXiv:1108.4971,Bibcode:2012AstL...38..331A,doi:10.1134/S1063773712050015,S2CID 119257644.
  3. ^abcdVallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data 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.S2CID 244398875. Gaia DR3 record for this source atVizieR.
  4. ^abLaur, Jaan; et al. (February 2017), "Variability survey of brightest stars in selected OB associations",Astronomy & Astrophysics,598: 27,arXiv:1611.02452,Bibcode:2017A&A...598A.108L,doi:10.1051/0004-6361/201629395,S2CID 119076598, A108.
  5. ^abcdLeedjaerv, Laurits (October 1998), "A spectroscopic study of the long-period binary star WY Geminorum",Astronomy and Astrophysics,338:139–150,Bibcode:1998A&A...338..139L.
  6. ^Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars",Astronomy Reports, GCVS 5.1,61 (1):80–88,Bibcode:2017ARep...61...80S,doi:10.1134/S1063772917010085,S2CID 255195566.
  7. ^abBrown, A. G. A.; et al. (Gaia collaboration) (August 2018)."Gaia Data Release 2: Summary of the contents and survey properties".Astronomy & Astrophysics.616. A1.arXiv:1804.09365.Bibcode:2018A&A...616A...1G.doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source atVizieR.
  8. ^Ryan Norris."Student Science at NMT: Learning Optical Interferometry Through Projects on Evolved Stars"(PDF).CHARA.
  9. ^abcCenarro, A. J.; et al. (January 2007), "Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters",Monthly Notices of the Royal Astronomical Society,374 (2):664–690,arXiv:astro-ph/0611618,Bibcode:2007MNRAS.374..664C,doi:10.1111/j.1365-2966.2006.11196.x,S2CID 119428437.
  10. ^"WY Gem",SIMBAD,Centre de données astronomiques de Strasbourg, retrieved2024-02-09.
  11. ^Humason, M. L. (April 1922), "An M-Type Star Whose Spectrum Contains Bright Lines",Publications of the Astronomical Society of the Pacific,34 (198): 133,Bibcode:1922PASP...34..133H,doi:10.1086/123170,S2CID 119888135.
  12. ^Swings, P.; Struve, O. (May 1941), "The Emission Lines in the Spectra of B 1985 and WY Geminorum",Astrophysical Journal,93: 455,Bibcode:1941ApJ....93..455S,doi:10.1086/144287.
  13. ^Martini, A. (1969), "The spectrum of W Y Gem in the years 1967-68",Memorie della Società Astronomia Italiana,40: 25,Bibcode:1969MmSAI..40...25M.
  14. ^Cowley, Anne (April 1970), "WY Geminorum-An Eclipsing System?",Publications of the Astronomical Society of the Pacific,82 (485): 329,Bibcode:1970PASP...82..329C,doi:10.1086/128912.
  15. ^Buzzoni, A. (November 1981), "WY Gem: a new semi-regular variable with a period of 169 days",GEOS Circular on Semi-Regular Variables,SR 2,Bibcode:1981GEOCS...2.....B.
  16. ^Hjellming, R. M. (July 1985), Hjellming, Robert M.; Gobson, David M. (eds.), "The Radio Emission of VV Cephei-type Binaries",Radio Stars, Astrophysics and Space Science Library,116: 151,Bibcode:1985ASSL..116..151H,doi:10.1007/978-94-009-5420-5_23,ISBN 90-277-2063-0.
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