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]

References

  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b c Anderson, 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. ^ a b Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  4. ^ Cannon, A. J.; Pickering, E. C. (October 1, 1993), "Henry Draper Catalogue and Extension (Cannon+ 1918-1924; ADC 1989)", VizieR Online Data Catalog, 3135, Bibcode:1993yCat.3135....0C.
  5. ^ a b Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  6. ^ a b c d e Gieren, Wolfgang P.; et al. (April 1990), "The Short-Period Cepheid EU Tau. II. Physical Properties of the Star", Astronomical Journal, 99: 1196, Bibcode:1990AJ.....99.1196G, doi:10.1086/115408.((citation)): CS1 maint: multiple names: authors list (link)
  7. ^ Bersier, D.; et al. (April 1997), "Fundamental parameters of Cepheids. IV. Radii and luminosities", Astronomy and Astrophysics, 320: 228–236, Bibcode:1997A&A...320..228B.
  8. ^ a b Marsakov, V. A.; et al. (2013), "Properties of the population of classical Cepheids in the Galaxy", Astronomy Letters, 39 (12): 851, Bibcode:2013AstL...39..851M, doi:10.1134/S1063773713120050, S2CID 119788977.
  9. ^ "EU Tau", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-06-24.
  10. ^ Evans, D. S.; Edwards, D. A. (August 1981), "Photoelectric observations of lunar occultations. XII", Astronomical Journal, 86: 1277−1287, Bibcode:1981AJ.....86.1277E, doi:10.1086/113008. In particular, the SAO 94837 entry on p. 1280.
  11. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  12. ^ Guinan, E. F. (December 1966), "EU Tauri", Information Bulletin on Variable Stars, 170: 1, Bibcode:1966IBVS..170....1G.
  13. ^ Guinan, E. F. (February 1972), "UBV beta photometry of EU Tau", Publications of the Astronomical Society of the Pacific, 84: 56, Bibcode:1972PASP...84...56G, doi:10.1086/129245, S2CID 120659500.
  14. ^ Simon, N. R.; Lee, A. S. (August 1981), "The structural properties of cepheid light curves", Astrophysical Journal, 248: 291–297, Bibcode:1981ApJ...248..291S, doi:10.1086/159153.
  15. ^ Boyer, Kirk; et al. (December 2007), "EU Tauri: An S-cepheid With A Changing Period", Bulletin of the American Astronomical Society, 39: 845, Bibcode:2007AAS...211.6014B.((citation)): CS1 maint: multiple names: authors list (link)

Further reading

  • Matthews, J. M.; Gieren, W. P. (1989), Schmidt, E. G. (ed.), "Secular Changes in the Light Curve of the Short-Period Cepheid EU Tau", The Use of pulsating stars in fundamental problems of astronomy, Proceedings of IAU Colloq. 111, held in Lincoln, NE, 15–17 August 1988, Cambridge University Press, p. 275, Bibcode:1989upsf.conf..275M.
  • Gieren, Wolfgang P.; et al. (November 1989), "The Short-Period Cepheid EU Tau. I. New Photometric and Radial Velocity Data", Astronomical Journal, 98: 1672, Bibcode:1989AJ.....98.1672G, doi:10.1086/115253.((citation)): CS1 maint: multiple names: authors list (link)
  • Fernie, J. D. (October 1987), "A check on EU Tauri", Publications of the Astronomical Society of the Pacific, 99: 1093–1096, Bibcode:1987PASP...99.1093F, doi:10.1086/132084, S2CID 120308156.
  • Matthews, Jaymie M.; Gieren, Wolfgang P. (1987), Cox, A. N.; et al. (eds.), "Frequency Analysis of the Unusual Short-Period Cepheid EU Tauri", Stellar Pulsation; Proceedings of the Conference held as a Memorial to John P. Cox at the Los Alamos National Laboratory, Los Alamos, NM, Aug. 11-15, 1986. Lecture Notes in Physics, Vol. 274, Lecture Notes in Physics, Berlin: Springer-Verlag, vol. 274, p. 187, Bibcode:1987LNP...274..187M, doi:10.1007/3-540-17668-3_202, ISBN 978-3-540-17668-8.
  • Gieren, W. P. (June 1985), Madore, B. F. (ed.), "A Study of the Short-period Cepheid EU-Tauri" (PDF), Cepheids: Theory and Observations, Proceedings of IAU Colloquium No. 82, held 29 May - 1 June 1984 in Toronto, Canada, New York: Cambridge University Press, no. 82, p. 98, Bibcode:1985cto..conf...98G, retrieved 2022-06-30.
  • Sanwal, N. B.; Parthasarathy, M. (January 1974), "UBV photometry of EU Tau.", Astronomy and Astrophysics Supplement Series, 13: 91–97, Bibcode:1974A&AS...13...91S.
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