Pi Tucanae (π Tuc, π Tucanae) is a double star[5] in the southern constellation of Tucana. It is visible to the naked eye with a combined apparent visual magnitude of 5.49.[2] Based upon an annual parallax shift of 10.25 mas as seen from Earth, it is located around 317 light years from the Sun.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Tucana |
| Right ascension | 0h 20m 39.03682s[1] |
| Declination | −69° 37′ 29.6821″[1] |
| Apparent magnitude (V) | 5.49[2] |
| Characteristics | |
| Spectral type | B9 V[3] |
| U−B color index | −0.11[2] |
| B−V color index | −0.05[2] |
| Astrometry | |
| Radial velocity (Rv) | 10.50±2.60[4] km/s |
| Proper motion (μ) | RA: −3.53[1] mas/yr Dec.: −0.10[1] mas/yr |
| Parallax (π) | 10.25 ± 0.21 mas[1] |
| Distance | 318 ± 7 ly (98 ± 2 pc) |
| Absolute magnitude (MV) | 0.57[5] |
| Details | |
| π Tuc A | |
| Mass | 2.8 0.21 −0.18[6] M☉ |
| Luminosity | 59[7] L☉ |
| Surface gravity (log g) | 4.0±0.14[6] cgs |
| Temperature | 11,393±387[6] K |
| Rotational velocity (v sin i) | 236[8] km/s |
| Age | 206 48 −79[6] Myr |
| π Tuc B | |
| Mass | 0.60[5] M☉ |
| Radius | 0.553[5][a] R☉ |
| Luminosity | 0.063[5] L☉ |
| Temperature | 3,890[5] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
The brighter star, component A, is a B-type main sequence star with a stellar classification of B9 V.[3] At an age of about 206 million years,[6] it is spinning rapidly with a projected rotational velocity of 236.[8] The star has an estimated 2.8[6] times the mass of the Sun and radiates 59[7] times the solar luminosity from its photosphere at an effective temperature of 11,393 K.[6]
There is a nearby visual companion, component B, but the two stars may not form a physical pair. This star has a K-band magnitude of 10.1 and is a source of X-ray emission. It has 60% of the Sun's mass and just 6.3% of the Sun's luminosity, with an effective temperature of 3,890 K.[5] The pair have an angular separation of 2.28 arc seconds along a position angle of 211.4°, which corresponds to a projected separation of 214.1 AU.[5]
Notes
edit- ^ calculated using temperature and luminosity
References
edit- ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Cousins, A. W. J.; Lagerweij, H. C. (1971), "UBV Observations of Variable Stars", Monthly Notes of the Astronomical Society of Southern Africa, 30: 12, Bibcode:1971MNSSA..30...12C.
- ^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
- ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 86351347, A61.
- ^ a b c d e f g h Hubrig, S.; et al. (June 2001), "Search for low-mass PMS companions around X-ray selected late B stars", Astronomy and Astrophysics, 372 (1): 152–164, arXiv:astro-ph/0103201, Bibcode:2001A&A...372..152H, doi:10.1051/0004-6361:20010452, S2CID 17507782.
- ^ a b c d e f g Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, S2CID 119179065, 40.
- ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
- ^ a b Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
- ^ "pi. Tuc -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-04-20.