Delta2 Gruis
Variable star in the constellation Grus
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Delta2 Gruis, Latinized from δ2 Gruis, is a solitary,[10] red-hued star in the southern constellation of Grus. It is visible to the naked eye with an apparent visual magnitude of about 4. Based upon an annual parallax shift of 9.88 mas as seen from the Earth, the star is located around 330 light years from the Sun. It is moving further away from the Sun with a radial velocity of +3 km/s.[5]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Grus |
| Right ascension | 22h 29m 45.43402s[1] |
| Declination | −43° 44′ 57.1968″[1] |
| Apparent magnitude (V) | 3.99 - 4.20[2] |
| Characteristics | |
| Spectral type | M4.5 IIIa[3] |
| U−B color index | +1.71[4] |
| B−V color index | +1.57[4] |
| Variable type | LB?[2] |
| Astrometry | |
| Radial velocity (Rv) | +2.7±0.8[5] km/s |
| Proper motion (μ) | RA: −14.08[1] mas/yr Dec.: +2.57[1] mas/yr |
| Parallax (π) | 9.1556±0.1885 mas[6] |
| Distance | 356 ± 7 ly (109 ± 2 pc) |
| Absolute magnitude (MV) | −0.90±0.05[3] |
| Details | |
| Radius | 97[7] R☉ |
| Luminosity | 1,359[7] L☉ |
| Surface gravity (log g) | +0.45[7] cgs |
| Temperature | 3,560[7] K |
| Rotational velocity (v sin i) | +4.5±0.8[8] km/s |
| Other designations | |
| δ2 Gru, CD−44°14935, HD 213080, HIP 111043, HR 8560, SAO 231161, WDS J22298-4345A[9] | |
| Database references | |
| SIMBAD | data |
This is an evolved red giant star with a stellar classification of M4.5 IIIa.[3] It is a pulsating variable with multiple periods, including 20.6, 24.1, 24.5, and 32.3 days. The strongest period is 33.3 days with an amplitude of 0.043 magnitude.[12] It has a magnitude 9.71 visual companion at an angular separation of 60.4 arc seconds along a position angle of 210°, as of 2013.[13]