Astronomy:Theta Arietis

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Short description: Binary star system in the constellation Aries
θ Arietis
Location of θ Arietis (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aries
Right ascension  02h 18m 07.53022s[1]
Declination +19° 54′ 04.1717″[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]
Variable type Constant[5]
Astrometry
Radial velocity (Rv)+6.0[2] km/s
Proper motion (μ) RA: −7.491[1] mas/yr
Dec.: −3.978[1] mas/yr
Parallax (π)7.6084 ± 0.1763[1] mas
Distance429 ± 10 ly
(131 ± 3 pc)
Absolute magnitude (MV)−0.10[6]
Details
A
Mass2.10+0.37
−0.31 M☉[7]
2.94±0.06[8] M☉
Radius1.9–2.5[9] R☉
Luminosity106[6] L☉
Surface gravity (log g)4.00±0.25[7] cgs
Temperature9,500±1,000[7] K
Rotational velocity (v sin i)186[10] km/s
Age107+286
−93[7] Myr
B
Mass1.0+0.02
−0.04[7] M☉
Temperature5,578±109[7] K
Metallicity [Fe/H]0.0[7] dex
Rotational velocity (v sin i)5[7] km/s
Other designations
θ Ari, 22 Arietis, BD+19 340, FK5 81, HD 14191, HIP 10732, HR 669, SAO 92877[11]
Database references
SIMBADdata

Theta Arietis, Latinised from θ Arietis, is the Bayer designation for a binary star[7] system 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 7.61 mas,[1] the distance to this star is an estimated 429 light-years (132 parsecs) with a 10-light-year margin of error. It is drifting further away with a radial velocity of +6 km/s.[2]

The primary, component A, 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.[10] This is causing the "nebulous" appearance of the absorption lines indicated by the 'n' suffix in the classification. In 2005, C. Neiner and associates classified this as a Be star because is displays emission features in the hydrogen Balmer lines.[5]

In 2016, a solar-mass companion was reported in close orbit around this star, based on observations using adaptive optics with the Gemini North Telescope.[7]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Wielen, R. et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg (Astronomisches Rechen-Institut Heidelberg) 35 (35): 1, Bibcode: 1999VeARI..35....1W. 
  3. ↑ 3.0 3.1 Cowley, A. et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal 74: 375–406, doi:10.1086/110819, Bibcode: 1969AJ.....74..375C. 
  4. ↑ 4.0 4.1 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. ↑ 5.0 5.1 Neiner, C. et al. (February 2005), "The Identification of New Be Stars in GAUDI", The Astrophysical Journal Supplement Series 156 (2): 237–243, doi:10.1086/426670, Bibcode: 2005ApJS..156..237N. 
  6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 Gullikson, Kevin et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal 152 (2): 13, doi:10.3847/0004-6256/152/2/40, 40, Bibcode: 2016AJ....152...40G. 
  8. ↑ Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics 537: A120, doi:10.1051/0004-6361/201117691, Bibcode: 2012A&A...537A.120Z. 
  9. ↑ 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 (2): 521–524, doi:10.1051/0004-6361:20000451, Bibcode: 2001A&A...367..521P. 
  10. ↑ 10.0 10.1 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, doi:10.1051/0004-6361:20065224, Bibcode: 2007A&A...463..671R. 
  11. ↑ "* tet Ari". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+tet+Ari. 



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