HU Tauri

A light curve for HU Tauri plotted from TESS data[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 04h 38m 15.830s[2]
Declination −19° 05′ 32.96″[2]
Apparent magnitude (V) 5.85[3]
Characteristics
Spectral type B8V + G2IV[4]
B−V color index −0.019±0.007[5]
Variable type Semi-detached Algol variable[3]
Astrometry
Radial velocity (Rv)−2.3±4.3[6] km/s
Proper motion (μ) RA: −12.899 mas/yr[2]
Dec.: −7.198 mas/yr[2]
Parallax (π)7.8722 ± 0.0466 mas[2]
Distance414 ± 2 ly
(127.0 ± 0.8 pc)
Absolute magnitude (MV)0.83[5]
Orbit[7]
Period (P)2.0563056 d
Eccentricity (e)0 (assumed)
Periastron epoch (T)2,446,487.5 HJD
Semi-amplitude (K1)
(primary)		59.3±0.85 km/s
Semi-amplitude (K2)
(secondary)		231.2±2.2 km/s
Details[7]
Primary
Mass4.43±0.09 M☉
Radius2.57±0.03 R☉
Luminosity123 L☉
Surface gravity (log g)4.26±0.014 cgs
Temperature12,000±1,000 K
Rotational velocity (v sin i)80 km/s
Secondary
Mass1.14±0.03 M☉
Radius4.21±0.03 R☉
Luminosity8.3 L☉
Surface gravity (log g)3.48±0.014 cgs
Temperature5,740±150 K
Other designations
HU Tau, BD+20°785, FK5 2341, GC 5644, HD 29365, HIP 21604, HR 1471, SAO 76680, PPM 93646, BV 312[8]
Database references
SIMBADdata

HU Tauri is a tight binary star system in the equatorial constellation of Taurus. It is an eclipsing binary, which means that the member stars periodically eclipse each other every 2.056 days. They have a combined apparent visual magnitude of 5.85,[3] which is bright enough to be dimly visible to the naked eye. During the primary eclipse, the magnitude drops to 6.68, while the secondary eclipse decreases the magnitude to 5.91. The distance to this system, based on parallax measurements, is approximately 414 light years.[2]

The variable nature of this system was reported by W. Strohmeier and R. Knigge in 1960. In 1963, Strohmeier found a period of 2.056297 days, and A. Mammano and associates derived orbital elements for a single-lined spectroscopic binary in 1967. A light curve for the system was assembled by O. Tümer and M. Kurutaç in 1979.[9] M. Parthasarathy and M. B. K. Sarma in 1980 noted asymmetries in the light curve near the primary eclipse, which suggested gas streams are partially obscuring the light from the primary component.[10]

This is a semidetached binary system with an orbital period of 2.0563056 days in an essentially circular orbit. The primary component is presently a B-type main-sequence star with a stellar classification of B8V. It has 4.4 times the mass and 2.6 times the radius of the Sun.[7] The primary eclipse is an occultation in which the secondary completely covers the primary. The cooler and larger secondary star is over-luminous for its mass, indicating that it has evolved away from the main sequence, and is filling its Roche lobe. The spectrum of the system suggests that the secondary is undergoing mass loss, with a gas stream transferring matter to the primary.[11]

References

  1. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  2. ^ 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.
  3. ^ a b c 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. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  5. ^ a b 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.
  6. ^ 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.
  7. ^ a b c Maxted, P. F. L.; et al. (September 1995), "Studies of early-type variable stars. XIV. Spectroscopic orbit and absolute parameters of HU Tauri", Astronomy and Astrophysics, 301: 141, Bibcode:1995A&A...301..141M.
  8. ^ "HU Tau", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-07-06.
  9. ^ Tumer, O.; Kurutac, M. (February 1979), "The Photoelectric Minima and the Light Curve of the Eclipsing Binary HU Tauri (BV 312)", Information Bulletin on Variable Stars, 1547: 1, Bibcode:1979IBVS.1547....1T.
  10. ^ Parthasarathy, M.; Sarma, M. B. K. (October 1980), "Photometry of HU Tauri", Astrophysics and Space Science, 72 (2): 477–496, Bibcode:1980Ap&SS..72..477P, doi:10.1007/BF00639151, S2CID 122841421.
  11. ^ Parthasarathy, M.; et al. (May 1995), "Photometric elements, absolute dimensions and evolutionary status of the eclipsing binary HU Tauri (HR 1471)", Astronomy and Astrophysics, 297: 359, Bibcode:1995A&A...297..359P.

Further reading

  • Parthasarathy, M. (January 2018), "Spectroscopy of bright Algol-type semi-detached close binary system HU Tauri (HR 1471)", Information Bulletin on Variable Stars, 6233 (6233): 1, arXiv:1707.06332, Bibcode:2018IBVS.6233....1M, doi:10.22444/IBVS.6233, S2CID 119413134.
  • Nakamura, Yasuhisa; et al. (June 1994), "A Light-Curve Analysis of the Eclipsing Binary System HU Tauri", Publications of the Astronomical Society of Japan, 46: 267–271, Bibcode:1994PASJ...46..267N.
  • Parthasarathy, M.; et al. (September 1993), "Photometric elements, absolute dimensions and evolutionary status of the eclipsing binary HU Tauri", Bulletin of the Astronomical Society of India, 21: 601–604, Bibcode:1993BASI...21..601P.
  • Ito, Yoshiharu (July 1988), "BV Observations of HU Tauri", Information Bulletin on Variable Stars, 3212: 1, Bibcode:1988IBVS.3212....1I.
  • Giuricin, G.; Mardirossian, F. (April 1981), "Photometric elements of the eclipsing binary HU Tau", Astronomy and Astrophysics, 97: 410–411, Bibcode:1981A&A....97..410G.
  • Dumitrescu, A.; Dinescu, R. (February 1980), "The Elements of the Eclipsing Binary HU Tauri", Information Bulletin on Variable Stars, 1740: 1, Bibcode:1980IBVS.1740....1D.
  • Margoni, R.; Mammano, A. (March 1966), "Velocity Curve of BV 312 Tauri", Information Bulletin on Variable Stars, 124: 1, Bibcode:1966IBVS..124....1M.
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