Pi Tucanae

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.

Pi Tucanae

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
π Tuc, CPD−70°12, FK5 2018, HD 1685, HIP 1647, HR 83, SAO 248167[9]
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

1. calculated using temperature and luminosity