Upsilon Capricorni
Star in the constellation Capricornus
From Wikipedia, the free encyclopedia
Upsilon Capricorni is a solitary,[10] reddish hued star in the southern constellation of Capricornus. Its name is a Bayer designation that is Latinized from υ Capricorni, and abbreviated Upsilon Cap or υ Cap. This star is dimly visible to the naked eye with an apparent visual magnitude of 5.17.[4] The star is about 630 light years away based on parallax,[2] but is drifting closer with a radial velocity of −12 km/s.[7] It is 0.22 degree north of the ecliptic, so is subject to lunar occultations.[11][12]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus[1] |
| Right ascension | 20h 40m 02.944s[2] |
| Declination | −18° 08′ 19.17″[3] |
| Apparent magnitude (V) | 5.17[4] |
| Characteristics | |
| Evolutionary stage | asymptotic giant branch[5] |
| Spectral type | M1 III[6] |
| B−V color index | +1.65[4] |
| Astrometry | |
| Radial velocity (Rv) | −12.3±1.6[7] km/s |
| Proper motion (μ) | RA: −22.764 mas/yr[2] Dec.: −22.170 mas/yr[2] |
| Parallax (π) | 5.1719±0.1354 mas[2] |
| Distance | 630 ± 20 ly (193 ± 5 pc) |
| Absolute magnitude (MV) | −1.09[1] |
| Details | |
| Radius | 92±4[8] R☉ |
| Luminosity | 1,283.0±76.5[3] L☉ |
| Temperature | 3,953+427 −193[3] K |
| Metallicity [Fe/H] | −0.08[1] dex |
| Other designations | |
| υ Cap, 15 Capricorni, NSV 25208, BD−18°5738, FK5 773, HD 196777, HIP 101984, HR 7900, SAO 163779[9] | |
| Database references | |
| SIMBAD | data |
This is an aging red giant star on the asymptotic giant branch[5] with a stellar classification of M1 III,[6] a star that has exhausted the supply of hydrogen at its core then cooled and expanded. It has 92 times the radius of the Sun[8] and is radiating 1,283 times the luminosity of the Sun[3] from its swollen photosphere at an effective temperature of 3,953 K.[3]
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.[13]