Alpha Tucanae
 Location of α Tucanae (circled) |
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| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Tucana |
| Right ascension | 22h 18m 30.09478s[1] |
| Declination | –60° 15′ 34.5263″[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: –70.72[1] mas/yr Dec.: –39.44[1] mas/yr |
| Parallax (π) | 16.33 ± 0.59[1] mas |
| Distance | 200 ± 7 ly (61 ± 2 pc) |
| Orbit[5] | |
| 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 |
| Other designations | |
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 200 light-years (61 parsecs).[1]
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).[5] 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.
[edit] 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, Bibcode 2007A&A...474..653V, doi:10.1051/0004-6361:20078357
- ^ a b c d Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode 1966CoLPL...4...99J
- ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 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: 341, Bibcode 1968MNRAS.139..341B
- ^ a b Pourbaix, D. et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics 424, Bibcode 2009yCat....102020P
- ^ "alf Tuc -- Spectroscopic binary", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Tucanae, retrieved 2012-01-20
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