Pi1 Gruis
Surface of the red giant star π1 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 + main sequence |
| Spectral type | S5,7: + G0V + F8V |
| Variable type | SRb |
| Astrometry | |
| Radial velocity (Rv) | −14.8±1.0 km/s |
| Proper motion (μ) | RA: +45.20±0.14 mas/yr Dec.: −18.78±0.06 mas/yr |
| Parallax (π) | 5.555±0.309 mas |
| Distance | 590 ± 30 ly (180 ± 10 pc) |
| Absolute magnitude (MV) | B: +4.3 |
| Orbit | |
| Primary | A |
| Name | B |
| Period (P) | 6,200 years |
| Semi-major axis (a) | 2.8" (460 AU) |
| Orbit | |
| Primary | A |
| Name | C |
| Period (P) | 11.76±1.85 years |
| Semi-major axis (a) | 6.81±0.49 AU |
| Eccentricity (e) | 0 |
| Inclination (i) | 11±7° |
| Longitude of the node (Ω) | 101±36° |
| Periastron epoch (T) | 2016.39±1.18 |
| Details | |
| A | |
| Mass | 1.12±0.25 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 | 1.18±0.27 M☉ |
| Radius | 1.31±0.09 R☉ |
| Luminosity | 2.25±0.10 L☉ |
| Surface gravity (log g) | 4.3±0.2 cgs |
| Temperature | 6,100±120 K |
| Other designations | |
| CD−46°14292, HR 8521, HD 212087, SAO 231105, HIP 110478 | |
| Database references | |
| SIMBAD | data |
Pi1 Gruis (π1 Gruis) is a semiregular variable star in the constellation Grus around 590 light-years from Earth. It forms a close double star with π2 Gru four arc-minutes away.