Gamma Tucanae, Latinized from γ Tucanae, is a star in the constellation Tucana, marking the toucan's beak.[13] 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.[7]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Tucana |
Right ascension | 23h 17m 25.77222s[1] |
Declination | −58° 14′ 08.6287″[1] |
Apparent magnitude (V) | +3.99[2] |
Characteristics | |
Spectral type | F1 III[2][3] or F3 IV/V[4] or F4 V[5] |
U−B color index | -0.02[6] |
B−V color index | +0.39[6] |
Astrometry | |
Radial velocity (Rv) | +18.4±0.7[7] 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[8] |
Details | |
Mass | 1.55[2] M☉ |
Radius | 2.2[9] R☉ |
Luminosity | 11.33[8] L☉ |
Surface gravity (log g) | 3.92[10] cgs |
Temperature | 6,679[10] K |
Metallicity [Fe/H] | −0.22[8] dex |
Rotational velocity (v sin i) | 94[11] km/s |
Age | 1.414[10] Gyr |
Other designations | |
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.[3] 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.[4] Gray et al. (2006) has it classed as F4 V, which would match an ordinary F-type main-sequence star.[5]
This star is a suspected astrometric binary.[14] The visible component has 1.55 times the mass of the Sun[2] and 2.2[9] times the Sun's radius. At the age of around 1.4[10] billion years, it retains a relatively high rate of spin with a projected rotational velocity of 94 km/s.[11] It is radiating 11[8] times the Sun's luminosity from its photosphere at an effective temperature of 6,679 K.[10]
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).[15]