Upsilon Capricorni, Latinized from υ Capricorni, is a solitary[7] star in the southern constellation of Capricornus. It has a reddish hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.17.[2] The star is about 730 light years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −12 km/s.[4] It is 0.22 degree north of the ecliptic, so is subject to lunar occultations.[8][9]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 20h 40m 02.94518s[1] |
| Declination | −18° 08′ 19.1664″[1] |
| Apparent magnitude (V) | 5.17[2] |
| Characteristics | |
| Spectral type | M1 III[3] |
| B−V color index | +1.65[2] |
| Astrometry | |
| Radial velocity (Rv) | −12.3±1.6[4] km/s |
| Proper motion (μ) | RA: −23.503[1] mas/yr Dec.: −22.157[1] mas/yr |
| Parallax (π) | 4.4702 ± 0.2352 mas[1] |
| Distance | 730 ± 40 ly (220 ± 10 pc) |
| Absolute magnitude (MV) | −1.09[5] |
| Details | |
| Radius | 76.36+8.05 −14.16[1] R☉ |
| Luminosity | 1,283.0±76.5[1] L☉ |
| Temperature | 3,953+427 −193[1] K |
| Metallicity [Fe/H] | −0.08[5] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an aging red giant star on the asymptotic giant branch[10] with a stellar classification of M1 III,[3] a star that has exhausted the supply of hydrogen at its core then cooled and expanded. At present it has 76[1] times the radius of the Sun. It is a suspected variable star of unknown type with a brightness that has been measured ranging from a peak of 5.19 down to 5.24.[11] The star is radiating 1,283[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,953 K.[1]