Astronomy:Theta Arietis

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Short description: Binary star system in the constellation Aries
θ Arietis
Aries constellation map.svg
Red circle.svg
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. Bibcode2018A&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, Bibcode1999VeARI..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, Bibcode1969AJ.....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, Bibcode1969AcA....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, Bibcode2005ApJS..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, Bibcode2012AstL...38..331A. 
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 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, Bibcode2016AJ....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, Bibcode2012A&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, Bibcode2001A&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, Bibcode2007A&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. 

External links