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Pi Tucanae
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Tucana
Right ascension	0h 20m 39.03682s
Declination	−69° 37′ 29.6821″
Apparent magnitude (V)	+5.49
Characteristics
Spectral type	B9 V
U−B color index	−0.11
B−V color index	−0.05
Astrometry
Radial velocity (Rv)	+10.50±2.60 km/s
Proper motion (μ)	RA: −3.53 mas/yr ; Dec.: −0.10 mas/yr
Parallax (π)	10.25 ± 0.21 mas
Distance	318 ± 7 ly ; (98 ± 2 pc)
Absolute magnitude (MV)	+0.57
Details
π Tuc A
Mass	2.8+0.21; −0.18 M☉
Luminosity	59 L☉
Surface gravity (log g)	4.0±0.14 cgs
Temperature	11,393±387 K
Rotational velocity (v sin i)	236 km/s
Age	206+48; −79 Myr
π Tuc B
Mass	0.60 M☉
Radius	0.553 R☉
Luminosity	0.063 L☉
Temperature	3,890 K
Other designations
	π Tuc, CPD−70° 12, FK5 2018, HD 1685, HIP 1647, HR 83, SAO 248167
Database references
SIMBAD	data

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.

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

^ calculated using temperature and luminosity

References

^ ^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 59451347, 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.