Theta Arietis

Theta Arietis, Latinized from θ Arietis, is the Bayer designation for a star in the northern constellation of Aries. It is faintly visible to the naked eye with an apparent visual magnitude of 5.58.[2] With an annual parallax shift of 7.29 mas,[1] the distance to this star is an estimated 450 light-years (140 parsecs) with a 20 light-year margin of error.

θ Arietis
Location of θ Arietis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension  02h 18m 07.53838s[1]
Declination +19° 54′ 04.1862″[1]
Apparent magnitude (V) 5.58[2]
Characteristics
Spectral type A1 Vn[3]
U−B color index +0.02[4]
B−V color index +0.01[4]
Astrometry
Radial velocity (Rv)+6.0[2] km/s
Proper motion (μ) RA: –13.19[1] mas/yr
Dec.: +0.72[1] mas/yr
Parallax (π)7.29 ± 0.29[1] mas
Distance450 ± 20 ly
(137 ± 5 pc)
Absolute magnitude (MV)−0.10[5]
Details
Radius1.9–2.5[6] R☉
Luminosity106[5] L☉
Rotational velocity (v sin i)186[7] km/s
Other designations
θ Ari, 22 Arietis, BD+19 340, FK5 81, HD 14191, HIP 10732, HR 669, SAO 92877.[8]
Database references
SIMBADdata

This is a white-hued, A-type main sequence star with a stellar classification of A1 Vn.[3] It is spinning at a rapid pace as shown by the projected rotational velocity of 186 km/s.[7] This is causing the "nebulous" appearance of the absorption lines indicated by the 'n' suffix in the classification.

References
  1. van Leeuwen, F. (November 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. Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions, Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W.
  3. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. Rybka, E. (1969), "The corrected magnitudes and colours of 278 stars near S.A. 1-139 in the UBV system", Acta Astronomica, 19: 229, Bibcode:1969AcA....19..229R.
  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. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  8. "* tet Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-08-06.
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