Tau7 Eridani

Tau7 Eridani is a solitary star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 5.235.[2] Using the parallax method, the distance to this star can be estimated as around 251 light years.[1]

For other star systems with this Bayer designation, see Tau Eridani.
τ7 Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension  03h 47m 39.65058s[1]
Declination −23° 52′ 28.8352″[1]
Apparent magnitude (V) 5.235[2]
Characteristics
Spectral type A3 Vs[3]
U−B color index +0.168[2]
B−V color index +0.067[2]
Astrometry
Radial velocity (Rv)28.4±0.5[4] km/s
Proper motion (μ) RA: +47.46[1] mas/yr
Dec.: +49.10[1] mas/yr
Parallax (π)13.00 ± 0.28[1] mas
Distance251 ± 5 ly
(77 ± 2 pc)
Absolute magnitude (MV)+0.81[5]
Details
τ7 Eri A
Mass2.03[6] M☉
Luminosity37.6[7] L☉
Surface gravity (log g)3.86±0.2[8] cgs
Temperature8,740±200[8] K
Rotational velocity (v sin i)18[8] km/s
Age387[6] Myr
Other designations
τ7 Eridani, τ7 Eri, 28 Eridani, CD−24° 1877, HD 23878, HIP 17717, HR 1181, SAO 168836.[9]
Database references
SIMBADdata

This is an A-type main sequence star with a stellar classification of A3 Vs,[3] where the 's' indicates it has narrow absorption lines. It may be a chemically peculiar Am star, which means it displays unusual abundances of certain elements in its surface layers. Tau7 Eridani appears to be a low amplitude variable that displays slight fluctuations in luminosity over a period of 7.17 days. It is slowly rotating with a projected rotational velocity of 18 km/s,[8] and is around 387 million years old.[6]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G.
  3. Abt, Helmut A.; Morrell, Nidia I. (July 1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
  4. De Bruijne, J. H. J.; Eilers, A.-C. (2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: A61, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219.
  5. 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.
  6. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  7. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  8. Khalack, V.; LeBlanc, F. (July 2015), "Project VeSElkA: Analysis of Balmer Line Profiles of Slowly Rotating Chemically Peculiar Stars", The Astronomical Journal, 150 (1): 10, arXiv:1505.08158, Bibcode:2015AJ....150....2K, doi:10.1088/0004-6256/150/1/2, 2.
  9. "tau07 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-13.
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