Alpha2 Capricorni
α¹ and α² are combined in this chart, to be held upwards, so west is right of page. Nu Capricorni to the east is not to be confused, nor 3 Capricorni even closer in angular distance to the west. | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 20h 18m 03.25595s |
| Declination | −12° 32′ 41.4684″ |
| Apparent magnitude (V) | +3.57 |
| Characteristics | |
| Spectral type | G8.5III-IV |
| U−B color index | +0.69 |
| B−V color index | +0.94 |
| Astrometry | |
| Radial velocity (Rv) | −0.47±0.47 km/s |
| Proper motion (μ) | RA: +62.63 mas/yr Dec.: +2.66 mas/yr |
| Parallax (π) | 31.9795±0.3485 mas |
| Distance | 102 ± 1 ly (31.3 ± 0.3 pc) |
| Absolute magnitude (MV) | +0.98+0.07 −0.06 |
| Details | |
| α2 Cap A | |
| Mass | 2.05±0.29 M☉ |
| Radius | 8.38±0.58 R☉ |
| Luminosity | 40.4±2.2 L☉ |
| Surface gravity (log g) | 3.0 cgs |
| Temperature | 5,030±160 K |
| Metallicity [Fe/H] | −0.15±0.10 dex |
| Rotational velocity (v sin i) | 2.7 km/s |
| Age | 1.30±1.04 Gyr |
| Other designations | |
| Gredi, Algedi, Secunda Giedi, Algiedi Secunda, α2 Cap, 6 Cap, ADS 13645, BD−12°5685, FK5 761, HD 192947, HIP 100064, HR 7754, SAO 163427, WDS J20181-1233A,BC | |
| Database references | |
| SIMBAD | data |
Alpha2 Capricorni (α2 Capricorni), or Algedi /ælˈdʒiːdi/, is a triple star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +3.57. It is separated from the fainter α¹ Capricorni by 0.11° of the sky, a gap just resolvable with the naked eye, similar to Mizar and Alcor. Based on parallax shift as refined from orbits around the Sun of the Gaia spacecraft at Earth's Lagrange point 2, the star is 101 to 103 light years from the Solar System.