Tau1 Capricorni
Star in the constellation Capricornus
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Tau1 Capricorni is a star in the constellation Capricornus. Its identifier is a Bayer designation that is Latinized from Ï1 Capricorni, and abbreviated Tau1 Cap or Ï1 Cap. This star has an apparent magnitude of 6.76,[1] making it readily visible in binoculars, but not to the naked eye. Located approximately 750 light years from Earth,[2] the star is receding with a heliocentric radial velocity of 18.5 km/s.[5] Due to its location near the ecliptic, Ï1 Cap can be occulted by the Moon and rarely planets.[7]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus[1] |
| Right ascension | 20h 37m 21.20s[2] |
| Declination | â15° 08â² 50.4â³[2] |
| Apparent magnitude (V) | +6.76[1] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | K1 III[3] |
| UâB color index | +1.23[4] |
| BâV color index | +1.26[4] |
| Astrometry | |
| Radial velocity (Rv) | 18.5±3[5] km/s |
| Proper motion (μ) | RA: 61.508 mas/yr[2] Dec.: â47.081 mas/yr[2] |
| Parallax (Ï) | 4.3504±0.0229 mas[2] |
| Distance | 750 ± 4 ly (230 ± 1 pc) |
| Absolute magnitude (MV) | â0.27[1] |
| Details | |
| Mass | 3.40+0.40 â0.04[2] Mâ |
| Radius | 21.4±0.5[2] Râ |
| Luminosity | 191+5 â3[2] Lâ |
| Surface gravity (log g) | 2.16+0.04 â0.01[2] cgs |
| Temperature | 4,626+57 â7[2] K |
| Metallicity [Fe/H] | â0.13[2] dex |
| Age | 270+25 â70[2] Myr |
| Other designations | |
| Ï1 Cap, 13 Capricorni, 34 G. Capricorni, BDâ15°5732, GC 28694, HD 196348, HIP 101751, SAO 163740[6] | |
| Database references | |
| SIMBAD | data |
Ï1 Capricorni has a stellar classification of K1 III, indicating that it is an ageing K-type giant.[3] At a modelled age of 270 million years, it has 3.4 times the mass of the Sun and an enlarged radius of 21 solar radii. It shines at 191 times the luminosity of the Sun from its photosphere at an effective temperature of 4,626 K.[2] Ï1 Cap's metallicity â elements heavier than helium â is at solar level.[8]