Pi2 Gruis

π² Gruis, Latinised as Pi² Gruis, is a binary star^[3] system in the southern constellation of Grus. It is faintly visible to the naked eye as a yellow-white hued star with an apparent visual magnitude of 5.622.^[2] Based upon an annual parallax shift of 25.1 mas as seen from the Earth,^[1] the system is located 130 light years from the Sun.

For other stars with this Bayer designation, see π Gruis.

Pi² Gruis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Grus
Right ascension	22h 23m 07.98704s[1]
Declination	−45° 55′ 42.5582″[1]
Apparent magnitude (V)	5.622[2] (5.71 + 11.3)[3]
Characteristics
Spectral type	F3 III-IV[4][3] or F0 V[5]
U−B color index	+0.016[2]
B−V color index	+0.365[2]
Astrometry
Radial velocity (Rv)	3.0[6] km/s
Proper motion (μ)	RA: +233.166[1] mas/yr Dec.: −58.205[1] mas/yr
Parallax (π)	25.1061±0.1256 mas[1]
Distance	129.9 ± 0.6 ly (39.8 ± 0.2 pc)
Absolute magnitude (MV)	2.62[7]
Details
π2 Gru A
Mass	1.37[8] M☉
Radius	1.93±0.07[1] R☉
Luminosity	7.15±0.04[1] L☉
Surface gravity (log g)	4.20[8] cgs
Temperature	6788+138 −101[1] K
Metallicity [Fe/H]	−0.06[6] dex
Age	758[8] Myr
Other designations
π2 Gru, CD−46°14295, FK5 3786, HD 212132, HIP 110506, HR 8524, SAO 231111, WDS J22231-4556[9]
Database references
SIMBAD	data

The primary, component A, is an F-type star of uncertain luminosity class. Malaroda (1975) gave it a stellar classification of F3 III-IV,^[4] which would indicate an evolving subgiant/giant star hybrid spectrum, whereas Houk (1978) listed it as class F0 V,^[5] suggesting that it is an F-type main sequence star. It has been considered to be a chemically peculiar star,^[10] but this is now considered doubtful.^[11] It is 758^[8] million years old with 1.4^[8] times the mass of the Sun. The star is 1.9^[1] times the Sun's radius and is radiating 7^[1] times the luminosity of the Sun from its photosphere at an effective temperature of 6,788 K.^[1]

The companion is a magnitude 11.3 star at an angular separation of 4.6 arc seconds.^[3] Gaia Data Release 2 has measured a separate annual parallax for it of 25.3266±0.0871 mas, almost identical to the primary star, and indicates that it is a red dwarf.^[12]