Astronomy:Rho2 Arae
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ara[1] |
| Right ascension | 16h 58m 17.940s[2] |
| Declination | −50° 38′ 28.27″[2] |
| Apparent magnitude (V) | 5.54[3] |
| Characteristics | |
| Spectral type | B9 IV[4] or B9 V[5] |
| B−V color index | +0.02[3] |
| Astrometry | |
| Radial velocity (Rv) | −44.0±4.3[6] km/s |
| Proper motion (μ) | RA: −9.758[2] mas/yr Dec.: −38.302[2] mas/yr |
| Parallax (π) | 5.2105 ± 0.0656[2] mas |
| Distance | 626 ± 8 ly (192 ± 2 pc) |
| Absolute magnitude (MV) | −0.47[1] |
| Details | |
| Mass | 3.42±0.10[7] M☉ |
| Radius | 5.104[8] R☉ |
| Luminosity | 238+34−30[7] L☉ |
| Temperature | 10,520±49[8] K |
| Rotational velocity (v sin i) | 302[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Rho2 Arae is a star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from ρ2 Arae, and abbreviated Rho2 Ara or ρ2 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.[3] Based upon an annual parallax shift of 6.28 mas, it is around 628 light-years (193 pc) distant from the Sun, give or take a 8-light-year margin of error.[2] The star is drifting closer to the Sun with a radial velocity of −44 km/s.[6]
The spectrum of this star matches a stellar classification of B9 IV[4] or B9 V.[5] The IV luminosity class suggests 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.[7]
Rho2 Arae has more than three times the mass of the Sun and 5.1 times the Sun's radius.[8] It is radiating 238 times the Sun's luminosity[7] from the star's photosphere at an effective temperature of 10,520 K,[8] giving it the blue-white hue of a B-type star.[10] The star is spinning rapidly with a projected rotational velocity of 302 km/s.[7]
References
- ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 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.
- ↑ 4.0 4.1 Hiltner, W. A. et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal 157: 313, doi:10.1086/150069, Bibcode: 1969ApJ...157..313H.
- ↑ 5.0 5.1 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.
- ↑ 6.0 6.1 Gontcharov, G. A. (2006), "Pulkovo compilation of radial velocities for 35495 stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Zorec, J.; Royer, F. (January 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.
- ↑ 8.0 8.1 8.2 8.3 Stassun, Keivan G. et al. (September 2019), "The Revised TESS Input Catalog and Candidate Target List" (in en), The Astronomical Journal 158 (4): 138, doi:10.3847/1538-3881/ab3467, ISSN 1538-3881, Bibcode: 2019AJ....158..138S.
- ↑ "rho02 Ara". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=rho02+Ara.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16.
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