WY Geminorum

WY Geminorum

A visual band light curve for WY Geminorum, plotted from ASAS-SN data[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Gemini[2]
Right ascension 06h 11m 56.250s[3]
Declination +23° 12′ 25.41″[3]
Apparent magnitude (V) 7.263 to 7.513[4]
Characteristics
Spectral type M2Ia-b + B2V[5]
B−V color index 1.517±0.017[2]
Variable type Irregular variable + eclipsing binary[6]
Astrometry
Radial velocity (Rv)19.52±0.22[7] km/s
Proper motion (μ) RA: 0.450 mas/yr[3]
Dec.: −2.380 mas/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
Periastron epoch (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 a binary star system in the northern constellation of Gemini, abbreviated WY Gem. It has an apparent visual magnitude that ranges from 7.26 down to 7.51,[4] which is too faint to be readily viewed with the naked eye. This system is located at a distance of approximately 6,300 light years from the Sun based on parallax measurements, and is receding with a radial velocity of 19.5 km/s.[7]

In 1922, M. L. Humason found the spectrum of HD 42474 matches an M-type star, but with the peculiarity of numerous bright lines. It appears similar to the spectrum of VV Cephei (HR 8383), an eclipsing binary.[11] P. Swings and O. Struve in 1941 discovered emission lines in the ultraviolet spectrum.[12] The presence of a B-type stellar spectrum from a companion star was confirmed by W. P. Bidelman in 1954. The primary spectrum matches an M-type supergiant 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 a semi-regular variable of the SRb type with a period of 169 days.[15]

This is a double-lined spectroscopic binary star system with an approximate orbital period of 64.48 ± 0.68 years and a high eccentricity (ovalness) of 0.61. The primary component is an M-type supergiant star with a stellar classification of M2Ia or b. The companion is most likely a hotter B-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 of periastron passage, resulting in the formation of an intermittent accretion disk orbiting the hotter star.[5] Radio emission has been detected, which is most likely coming from an ionized region in the stellar wind of the supergiant.[16]

  1. ^ Cite error: The named reference ASAS-SN was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Laur_et_al_2017 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Leedjaerv_1998 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Norris2023 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Cenarro_et_al_2007 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Humason_1922 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Swings_Struve_1941 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Martini_1969 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Cowley_1970 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Buzzoni_1981 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Hjellming_1985 was invoked but never defined (see the help page).