Gamma Tucanae
Star in the constellation Tucana
From Wikipedia, the free encyclopedia
Gamma Tucanae, Latinized from γ Tucanae, is a star in the constellation Tucana, marking the toucan's beak.[14] It is faintly visible to the naked eye with an apparent visual magnitude of +3.99.[2] Based upon an annual parallax shift of 43.37 mas as seen from Earth,[1] this star is located about 75 light years from the Sun. It is moving away from the Sun with a radial velocity of +18 km/s.[8]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Tucana |
| Right ascension | 23h 17m 25.77222s[1] |
| Declination | −58° 14′ 08.6287″[1] |
| Apparent magnitude (V) | +3.99[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | F1 III[2][4] or F3 IV/V[5] or F4 V[6] |
| U−B color index | −0.02[7] |
| B−V color index | +0.39[7] |
| Astrometry | |
| Radial velocity (Rv) | +18.4±0.7[8] km/s |
| Proper motion (μ) | RA: −35.83[1] mas/yr Dec.: +81.16[1] mas/yr |
| Parallax (π) | 43.37±0.63 mas[1] |
| Distance | 75 ± 1 ly (23.1 ± 0.3 pc) |
| Absolute magnitude (MV) | 2.18[9] |
| Details | |
| Mass | 1.55[2] M☉ |
| Radius | 2.2[10] R☉ |
| Luminosity | 11.33[9] L☉ |
| Surface gravity (log g) | 3.92[11] cgs |
| Temperature | 6,679[11] K |
| Metallicity [Fe/H] | −0.22[9] dex |
| Rotational velocity (v sin i) | 94[12] km/s |
| Age | 1.414[11] Gyr |
| Other designations | |
| γ Tuc, CPD−58°8062, FK5 877, GC 32413, GJ 9818, HD 219571, HIP 114996, HR 8848, SAO 247814, GSC 08837-01297[13] | |
| Database references | |
| SIMBAD | data |
There is disagreement in the literature as to the stellar classification of this star. Malaroda (1975) has it catalogued as F1 III, which would suggest it is an evolved F-type giant star.[4] Houk (1979) listed it as F3 IV/V, which appears to indicate a less evolved F-type star transitioning between the main sequence and subgiant star.[5] Gray et al. (2006) has it classed as F4 V, which would match an ordinary F-type main-sequence star.[6]
This star is a suspected astrometric binary.[15] The visible component has 1.55 times the mass of the Sun[2] and 2.2[10] times the Sun's radius. At the age of around 1.4[11] billion years, it retains a relatively high rate of spin with a projected rotational velocity of 94 km/s.[12] It is radiating 11[9] times the Sun's luminosity from its photosphere at an effective temperature of 6,679 K.[11]
Gamma Tucanae may (95% chance) have a distant co-moving companion – a magnitude 6.64 G-type main-sequence star of class G0 V designated HD 223913. This object has the same mass as the Sun and is separated from Gamma Tucanae by about 11 ly (3.5 pc).[16]