Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Tucana |
Right ascension | 22h 18m 30.11244s[1] |
Declination | −60° 15′ 34.6664″[1] |
Apparent magnitude (V) | 2.86[2] |
Characteristics | |
Spectral type | K3 III[3] |
U−B color index | +1.54[2] |
B−V color index | +1.39[2] |
Astrometry | |
Radial velocity (Rv) | +45.8[4] km/s |
Proper motion (μ) | RA: −77.000[1] mas/yr Dec.: −32.823[1] mas/yr |
Parallax (π) | 17.7324 ± 0.3290 mas[1] |
Distance | 184 ± 3 ly (56 ± 1 pc) |
Absolute magnitude (MV) | −1.05[5] |
Absolute bolometric magnitude (Mbol) | −1.97[5] |
Orbit[6] | |
Period (P) | 4197.7 days |
Eccentricity (e) | 0.39 |
Periastron epoch (T) | 18666.4 |
Argument of periastron (ω) (secondary) | 48.5° |
Semi-amplitude (K1) (primary) | 7.2 km/s |
Details | |
Mass | 2.5 - 3[7] M☉ |
Radius | 37[7] R☉ |
Luminosity | 424[7] L☉ |
Temperature | 4300[7] K |
Other designations | |
Database references | |
SIMBAD | data |
Alpha Tucanae (α Tuc, α Tucanae) is a binary star system in the southern circumpolar constellation of Tucana. With an apparent visual magnitude of 2.86,[2] it can be seen with the naked eye from the southern hemisphere. Using parallax measurements, the distance to this system can be estimated as 184 light-years (56 parsecs). A cool star with a surface temperature of 4300 K, it is 424 times as luminous as the sun and 37 times its diameter. It is 2.5 to 3 times as massive. It is unclear what stage of evolution the star is in.[7]
This is a spectroscopic binary, which means that the two stars have not been individually resolved using a telescope, but the presence of the companion has been inferred from measuring changes in the spectrum of the primary. The orbital period of the binary system is 4197.7 days (11.5 years).[6] The primary component has a stellar classification of K3 III,[3] which indicates it is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. It has the characteristic orange hue of a K-type star.
References
- 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- 1 2 3 4 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J
- 1 2 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1975mcts.book.....H
- ↑ Buscombe, W.; Kennedy, P. M. (1968), "Stellar radial velocities from coudé spectrograms", Monthly Notices of the Royal Astronomical Society, 139 (3): 341–346, Bibcode:1968MNRAS.139..341B, doi:10.1093/mnras/139.3.341
- 1 2 Pasquini, L.; de Medeiros, J. R.; Girardi, L. (2000). "Ca II activity and rotation in F-K evolved stars". Astronomy and Astrophysics. 361: 1011–1022. arXiv:astro-ph/0008109. Bibcode:2000A&A...361.1011P.
- 1 2 Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088
- 1 2 3 4 5 Kaler, Jim. "Alpha Tucanae". Stars. University of Illinois. Retrieved 19 October 2013.
- ↑ "alf Tuc -- Spectroscopic binary", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-20