Rho2 Arae
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ara |
| Right ascension | 16h 58m 17.94161s[1] |
| Declination | –50° 38′ 28.2691″[1] |
| Apparent magnitude (V) | 5.54[2] |
| Characteristics | |
| Spectral type | B9 IV[3] or B9 V[4] |
| B−V color index | +0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | –44.0[5] km/s |
| Proper motion (μ) | RA: –8.05[1] mas/yr Dec.: –38.68[1] mas/yr |
| Parallax (π) | 6.28 ± 0.38[1] mas |
| Distance | 520 ± 30 ly (159 ± 10 pc) |
| Details | |
| Mass | 3.42 ± 0.10[6] M☉ |
| Luminosity | 238[6] L☉ |
| Temperature | 10,520[6] K |
| Rotational velocity (v sin i) | 302[6] km/s |
| Other designations | |
Rho2 Arae is the Bayer designation for a star in the southern constellation of Ara. It received this designation when the star was catalogued by Bode in his Uranographia. This is a rather dim naked eye star with an apparent visual magnitude of 5.54.[2] Based upon an annual parallax shift of just 6.28 mas, it is around 520 light-years (160 parsecs) distant from the Sun, give or take a 30 light-year margin of error.[1]
The spectrum of this star matches a stellar classification of B9 IV[3] or B9 V.[4] The IV luminosity class would indicate the star is in the subgiant stage, while a V class means it is a main sequence star like the Sun. In the latter case, it is close to entering the subgiant stage at an estimated 93% of the way through its lifespan on the main sequence.[6]
Rho2 Arae has more than three times the mass of the Sun and shines with 238 times the Sun's luminosity.[6] This energy is being radiated into space from the outer atmosphere at an effective temperature of 10,520 K,[6] giving it the blue-white hue of a B-type star.[8] It is spinning rapidly with a projected rotational velocity of 302 km/s.[6]
References
- 1 2 3 4 5 6 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. - 1 2 3 Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
- 1 2 Hiltner, W. A.; Garrison, R. F.; Schild, R. E. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal, 157: 313, Bibcode:1969ApJ...157..313H, doi:10.1086/150069.
- 1 2 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
- ↑ Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W.
- 1 2 3 4 5 6 7 8 Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691
- ↑ "HR 6289 -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-08-02.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16.