21 Arietis

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21 Arietis
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension 02h 15m 42.77662s[1]
Declination +25° 02′ 34.9627″[1]
Apparent magnitude (V) 5.57[2] (6.40/6.48)[3]
Characteristics
Spectral type F6 V[4]
U−B color index +0.00[5]
B−V color index +0.50[5]
Astrometry
Radial velocity (Rv) –44.3 km/s
Proper motion (μ) RA: –89.72[1] mas/yr
Dec.: –86.42[1] mas/yr
Parallax (π) 19.58 ± 0.61[1] mas
Distance 167 ± 5 ly
(51 ± 2 pc)
Absolute magnitude (MV) 2.03[2]
Orbit[6]
Period (P) 23.70 ± 0.12 yr
Semi-major axis (a) 0.2353 ± 0.0011"
Eccentricity (e) 0.6816 ± 0.0037
Inclination (i) 104.52 ± 0.16°
Longitude of the node (Ω) 236.44 ± 0.22°
Periastron epoch (T) 1986.192 ± 0.012
Argument of periastron (ω)
(secondary)
84.16 ± 0.16°
Details
21 Ari A
Surface gravity (log g) 4.12[7] cgs
Temperature 6,299[7] K
Metallicity [Fe/H] +0.02[7] dex
Rotational velocity (v sin i) 12.6[8] km/s
Age 2.2[2] Gyr
Other designations
BD+24 329, FK5 1059, HD 13872, HIP 10535, HR 657, SAO 75238, WDS J02157+2503.[5]

21 Arietis is the Flamsteed designation for a binary star[3] system in the northern constellation of Aries. It has a combined apparent visual magnitude is 5.57;[2] the brighter member is magnitude 6.40 while the fainter star is magnitude 6.48.[3] The distance to this star system, based upon an annual parallax shift of 19.58 mas,[1] is 167 light-years (51 parsecs). The pair orbit each other with a period of 23.70 years and an eccentricity of 0.68.[3]

References[edit]

  1. ^ a b c d e f 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. ^ a b c d Holmberg, J.; Nordström, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191. 
  3. ^ a b c d 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. 
  4. ^ Harlan, E. A. (September 1969), "MK classifications for F- and G-type stars. I", Astronomical Journal 74: 916–919, Bibcode:1969AJ.....74..916H, doi:10.1086/110881. 
  5. ^ a b c "21 Ari -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-18. 
  6. ^ Hartkopf, William I.; Mason, Brian D.; McAlister, Harold A. (January 1996), "Binary Star Orbits From Speckle Interferometry. VIII. Orbits of 37 Close Visual System", Astronomical Journal 111: 370, Bibcode:1996AJ....111..370H, doi:10.1086/117790. 
  7. ^ a b c Balachandran, Suchitra (May 1, 1990), "Lithium depletion and rotation in main-sequence stars", Astrophysical Journal, Part 1 354: 310–332, Bibcode:1990ApJ...354..310B, doi:10.1086/168691. 
  8. ^ Schröder, C.; Reiners, A.; Schmitt, J. H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics 493 (3): 1099−1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377. 

External links[edit]