Pi2 Gruis
Binary star system in the constellation Grus From Wikipedia, the free encyclopedia
Binary star system in the constellation Grus From Wikipedia, the free encyclopedia
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.
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 | |
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]