Beta Gruis
Beta Gruis (β Gruis, abbreviated Beta Gru, β Gru), formally named Tiaki /tiˈɑːki/, is the second brightest star in the southern constellation of Grus. It was once considered the rear star in the tail of the constellation of the (Southern) Fish, Piscis Austrinus: it, with Alpha, Delta, Theta, Iota, and Lambda Gruis, belonged to Piscis Austrinus in medieval Arabic astronomy.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Grus |
| Right ascension | 22h 42m 40.05027s |
| Declination | −46° 53′ 04.4752″ |
| Apparent magnitude (V) | 2.146 (2.0 - 2.3) |
| Characteristics | |
| Evolutionary stage | AGB |
| Spectral type | M5 III |
| U−B color index | +1.757 |
| B−V color index | +1.620 |
| Variable type | SRb |
| Astrometry | |
| Radial velocity (Rv) | +1.6 km/s |
| Proper motion (μ) | RA: +135.16 mas/yr Dec.: −4.38 mas/yr |
| Parallax (π) | 18.43 ± 0.42 mas |
| Distance | 177 ± 4 ly (54 ± 1 pc) |
| Absolute magnitude (MV) | −1.61±0.052 |
| Details | |
| Mass | 2.4 M☉ |
| Radius | 138 R☉ |
| Luminosity | 2,500 L☉ |
| Surface gravity (log g) | 0.4 cgs |
| Temperature | 3,480 K |
| Metallicity [Fe/H] | 0.0 dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
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