Pi1 Gruis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Grus |
| Right ascension | 22h 22m 44.20571s |
| Declination | −45° 56′ 52.6115″ |
| Apparent magnitude (V) | 5.31 - 7.01 + 10.4 |
| Characteristics | |
| Evolutionary stage | AGB |
| Spectral type | S5,7: + G0V |
| Variable type | SRb |
| Astrometry | |
| Parallax (π) | 6.13±0.76 mas |
| Distance | approx. 530 ly (approx. 160 pc) |
| Absolute magnitude (MV) | G0: +4.3 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 6,200 years |
| Semi-major axis (a) | 2.8" (460 AU) |
| Orbit | |
| Primary | A |
| Companion | C |
| Period (P) | 11.0+1.7 −1.5 years |
| Semi-major axis (a) | 7.05+0.54 −0.57 AU |
| Eccentricity (e) | 0.35+0.18 −0.17 |
| Inclination (i) | 31.75–38.04° |
| Longitude of the node (Ω) | 321.7+5.91 −5.67° |
| Periastron epoch (T) | 2015.06+1.09 −1.14 |
| Argument of periastron (ω) (primary) | 359.00+7.87 −11.26° |
| Details | |
| A | |
| Mass | 1.54–2.19 M☉ |
| Radius | 319±23 R☉ |
| Luminosity | 7,440 L☉ |
| Temperature | 2,300 – 3,100 K |
| B | |
| Mass | 1.06 M☉ |
| Radius | 1.10 R☉ |
| Luminosity | 1.35 L☉ |
| Temperature | 5,930 K |
| C | |
| Mass | 0.86+0.22 −0.20 M☉ |
| Radius | If main sequence: 0.80+0.34 −0.17 R☉ If white dwarf: 0.009±0.002 R☉ |
| Luminosity | If main sequence: 0.41+1.10 −0.31 L☉ |
| Temperature | If main sequence: 5,170+820 −1,070 K |
| Other designations | |
| CD−46°14292, HR 8521, HD 212087, SAO 231105, HIP 110478 | |
| Database references | |
| SIMBAD | data |
π1 Gruis (Pi1 Gruis) is a semiregular variable star in the constellation Grus around 530 light-years from Earth. It forms a close double star with π2 Gru four arc-minutes away.