EU Tauri

EU Tauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 05h 45m 40.529s[1]
Declination 18° 39′ 24.82″[1]
Apparent magnitude (V) 8.07[2] (7.90 to 8.25)[3]
Characteristics
Spectral type G5[4]
B−V color index 0.676±0.018[2]
Variable type s-Cepheid[3]
Astrometry
Radial velocity (Rv)−2.5±0.3[5] km/s
Proper motion (μ) RA: 1.155 mas/yr[1]
Dec.: −2.455 mas/yr[1]
Parallax (π)0.8262 ± 0.0233 mas[1]
Distance3,900 ± 100 ly
(1,210 ± 30 pc)
Absolute magnitude (MV)−2.77±0.15[6]
Details
Mass4.95±0.20[6] M☉
Radius30.23±1.43[6] R☉
Luminosity1,038±140[6] L☉
Temperature6,404 (6,185 to 6,626)[7] K
Metallicity [Fe/H]−0.06[8] dex
Age195[8] Myr
Other designations
EU Tau, BD+18°955, HD 38321, HIP 27183, SAO 94837, PPM 121367[9]
Database references
SIMBADdata

EU Tauri is a variable star in the equatorial constellation of Taurus. With a brightness that cycles around an apparent visual magnitude of 8.07,[2] it is too faint to be visible to the naked eye. The distance to this star is approximately 3,900 light years based on parallax measurements,[1] but it is drifting closer with a radial velocity of −2.5 km/s.[5] The position of this star near the ecliptic means it is subject to lunar occultations.[10]

A light curve for EU Tauri, plotted from TESS data[11]

The variability of this star was first reported by C. Hoffmeister in 1949, who later reported it as not variable. It was initially classified as an eclipsing binary of the W Ursae Majoris type by F. B. Wood and associates in 1963, based on observations by T. A. Azarnova in 1950–1951. Analysis of photoelectric data by E. F. Guinan in 1966 suggested this is instead a cepheid-type variable with a short pulsation period of about 2.105 days.[12] He refined this period to 2.1051±0.0004 days in 1972.[13]

A study of the light curve of this and other cepheids in 1981 showed it belongs to a small group with unusually short periods and distinctive behavior. This indicated that EU Tauri may be a "first overtone" pulsator.[14] Gieren and J. M. Matthews in 1987 suggested that the star may instead have two pulsation periods, but this was later refuted. The evidence now mostly supports the idea that the pulsation of the star is in a "radial first overtone mode". The 1% radius variation during a pulsation cycle is relatively small for a star of this class.[6] By 2007, scattered observations over a 35-year time frame indicated that the pulsation period of this s-Cepheid may have changed.[15]

  1. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Cannon_Pickering_1993 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Gontcharov_2006 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference Gieren_et_al_1990 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Bersier_et_al_1997 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Marsakov_et_al_2013 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Evans_Edwards_1981 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Guinan_1966 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Guinan_1972 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Simon_Lee_1981 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Boyer_et_al_2007 was invoked but never defined (see the help page).