R Trianguli Australis
R Trianguli Australis is a yellow-white hued variable star in the southern constellation Triangulum Australe. It is near the limit of visibility to the naked eye, having a typical apparent visual magnitude of 6.73.[2] Based upon an annual parallax shift of 1.48 mas,[1] it is located 2,210 light years away. R TrA is moving closer with a heliocentric radial velocity of −13 km/s.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Triangulum Australe |
| Right ascension | 15h 19m 45.71231s[1] |
| Declination | −66° 29′ 45.7417″[1] |
| Apparent magnitude (V) | 6.73[2] (6.33 - 6.90)[3] |
| Characteristics | |
| Spectral type | F7 Ib/II[4] |
| Variable type | δ Cep[5] |
| Astrometry | |
| Radial velocity (Rv) | −13.2±1.6[6] km/s |
| Proper motion (μ) | RA: −5.113[1] mas/yr Dec.: −8.317[1] mas/yr |
| Parallax (π) | 1.4754 ± 0.0371[1] mas |
| Distance | 2,210 ± 60 ly (680 ± 20 pc) |
| Absolute magnitude (MV) | 2.69[7] |
| Details | |
| Mass | 5.42 or 5.66[8] M☉ |
| Radius | 24.7±1.9[9] or 35.8±0.8[8] R☉ |
| Surface gravity (log g) | 2.10[8] cgs |
| Temperature | 5,852±21[8] K |
| Metallicity [Fe/H] | +0.06±0.08[7] dex |
| Rotational velocity (v sin i) | 16 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a Classical Cepheid variable with an apparent magnitude that ranges from 6.33 to 6.90 over 3.38926 days.[3] It is a bright giant/supergiant with a nominal stellar classification of F7 Ib/II,[4] but pulsates between spectral types F5Ib/II-G5.[3] Depending on the method employed, the estimated mass is 5.42 or 5.66 times the mass of the Sun and it has 24.7 or 35.8 times the Sun's radius.[8] R TrA has an infrared excess that is being emitted by circumstellar silicate dust heated to 150–200 K. It is losing mass at the rate of 4×10−9 M☉·y−1.[8]
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
- Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
- Watson, Christopher (4 January 2010). "R Trianguli Australis". AAVSO Website. American Association of Variable Star Observers. Retrieved 23 May 2015.
- Houk, Nancy; Cowley, A. P. (1979). "Michigan catalogue of two-dimensional spectral types for the HD stars". 1. Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H. Cite journal requires
|journal=(help) - Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085.
- Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
- Luck, R. E.; et al. (August 2011). "The Distribution of the Elements in the Galactic Disk. II. Azimuthal and Radial Variation in Abundances from Cepheids". The Astronomical Journal. 142 (2): 12. arXiv:1106.0182. Bibcode:2011AJ....142...51L. doi:10.1088/0004-6256/142/2/51. 51.
- Usenko, I. A.; Kniazev, A. Yu.; Berdnikov, L. N.; Kravtsov, V. V. (2014). "Spectroscopic studies of Cepheids in Circinus (AV Cir, BP Cir) and Triangulum Australe (R TrA, S TrA, U TrA, LR TrA)". Astronomy Letters. 40 (12): 800. Bibcode:2014AstL...40..800U. doi:10.1134/S1063773714110061.
- Moskalik, P.; Gorynya, N. A. (2005). "Mean Angular Diameters and Angular Diameter Amplitudes of Bright Cepheids". Acta Astronomica. 55: 247. arXiv:astro-ph/0507076. Bibcode:2005AcA....55..247M.
- "R TrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 September 2018.