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 |
| Semimajor 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] |
| 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 | |
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
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ a b c "21 Ari -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-18.
- ^ 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.
- ^ 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.
- ^ 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
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