Astronomy:Epsilon Tucanae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Tucana |
| Right ascension | 23h 59m 54.97761s[1] |
| Declination | −65° 34′ 37.6804″[1] |
| Apparent magnitude (V) | +4.50[2] |
| Characteristics | |
| Spectral type | B8 V[3] or B9 IV[4] |
| U−B color index | −0.28[2] |
| B−V color index | −0.08[2] |
| Astrometry | |
| Radial velocity (Rv) | +8.8±2.8[5] km/s |
| Proper motion (μ) | RA: +47.93[1] mas/yr Dec.: −22.95[1] mas/yr |
| Parallax (π) | 8.74 ± 0.18[1] mas |
| Distance | 373 ± 8 ly (114 ± 2 pc) |
| Absolute magnitude (MV) | −0.80[6] |
| Details | |
| Mass | 4.00±0.20[3] M☉ |
| Luminosity | 389[3] L☉ |
| Surface gravity (log g) | 3.9±0.1[3] cgs |
| Temperature | 13,000±500[3] K |
| Rotation | 0.79318(8)[7] d |
| Rotational velocity (v sin i) | 300±20[3] km/s |
| Age | 123[3] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Tucanae (ε Tuc, ε Tucanae) is a solitary[9] star in the southern constellation of Tucana. With an apparent visual magnitude of +4.50,[2] it is faintly visible to the naked eye. Based upon an annual parallax shift of 8.74 mas as seen from Earth, it is located around 373 light years from the Sun.
Levenhagen and Leister (2008) classified this star as B8 V,[3] indicating a blue-white hued B-type main sequence star. However, Hiltner, Garrison, and Schild (1969) listed it with a classification of B9 IV,[4] suggesting it may be a more evolved subgiant star. It is a rapidly rotating Be star that is an estimated 78% of the way through its main sequence lifetime.[10] The projected rotational velocity is 300 km/s,[3] which is giving it an oblate shape with an equatorial bulge that is an estimated 36% larger than the polar radius.[11] It has a weak magnetic field with a strength of 74±24 G.[12]
It is the last star in the Hipparcos catalogue, HIP 118322, from the Hipparcos (1989–1993) astrometry satellite.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Levenhagen, R. S.; Leister, N. V. (2006), "Spectroscopic Analysis of Southern B and Be Stars", Monthly Notices of the Royal Astronomical Society 371 (1): 252–62, doi:10.1111/j.1365-2966.2006.10655.x, Bibcode: 2006MNRAS.371..252L.
- ↑ 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.
- ↑ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ Barraza, L. F.; Gomes, R. L.; Messias, Y. S.; Leão, I. C.; Almeida, L. A.; Janot-Pacheco, E.; Brito, A. C.; Brito, F. A. C. et al. (2022). "Rotation Signature of TESS B-type Stars. A Comprehensive Analysis". The Astrophysical Journal 924 (2): 117. doi:10.3847/1538-4357/ac3335. Bibcode: 2022ApJ...924..117B.
- ↑ "eps Tuc -- Be Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=eps+Tuc, retrieved 2017-04-22.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Zorec, J. et al. (October 2005), "On the evolutionary status of Be stars. I. Field Be stars near the Sun", Astronomy and Astrophysics 441 (1): 235–248, doi:10.1051/0004-6361:20053051, Bibcode: 2005A&A...441..235Z.
- ↑ Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review 20 (1): 51, doi:10.1007/s00159-012-0051-2, Bibcode: 2012A&ARv..20...51V.
- ↑ Hubrig, S. et al. (July 2009), "Magnetic survey of emission line B-type stars with FORS 1 at the VLT", Astronomische Nachrichten 330 (7): 708, doi:10.1002/asna.200911236, Bibcode: 2009AN....330..708H.
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