Delta Capricorni
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 21h 47m 02.44424s |
| Declination | −16° 07′ 38.2335″ |
| Apparent magnitude (V) | 2.81 min1: 2.90 min2: 3.05 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | A7m III (kA5hF0mF2III) |
| U−B color index | +0.07 |
| B−V color index | +0.31 |
| Variable type | Eclipsing binary (Algol-type) |
| Astrometry | |
| Radial velocity (Rv) | −6.3 km/s |
| Proper motion (μ) | RA: +261.70 mas/yr Dec.: −296.70 mas/yr |
| Parallax (π) | 84.27±0.19 mas |
| Distance | 38.70 ± 0.09 ly (11.87 ± 0.03 pc) |
| Absolute magnitude (MV) | +2.48 |
| Orbit | |
| Primary | δ Cap Aa |
| Name | δ Cap Ab |
| Period (P) | 1.0227683 days |
| Eccentricity (e) | 0 (assumed) |
| Inclination (i) | 72.5° |
| Periastron epoch (T) | 2448105.793±0.003 HJD |
| Semi-amplitude (K1) (primary) | 75.3 ± 1.0 km/s |
| Details | |
| δ Cap Aa | |
| Mass | 2.0 M☉ |
| Radius | 1.91 R☉ |
| Luminosity | 8.5 L☉ |
| Surface gravity (log g) | 3.66 cgs |
| Temperature | 7,301 K |
| Metallicity [Fe/H] | −0.13 dex |
| Rotational velocity (v sin i) | 105 km/s |
| δ Cap Ab | |
| Mass | 0.73 M☉ |
| Radius | 0.9 R☉ |
| Temperature | 4,500 K |
| Other designations | |
| Deneb Algedi, Deneb Algiedi, Scheddi, δ Cap, Del Cap, 49 Capricorni, BD−16 5943, FK5 819, GJ 837, HD 207098, HIP 107556, HR 8322, SAO 164644, ADS 15314, WDS 21470-1608 | |
| Database references | |
| SIMBAD | data |
Delta Capricorni is the brightest star in the constellation of Capricornus, the Sea Goat. It is a binary star system whose components are seen to eclipse each other, known as an eclipsing binary. The baseline apparent magnitude is 2.81, and during the primary and secondary eclipse it dims to 3.05 and 2.90, respectively. The system lies at a distance of 38.7 light-years (11.9 pc), based on parallax measurements.
The two components of this system are designated Delta Capricorni Aa and Delta Capricorni Ab. The former is the primary and has the proper name Deneb Algedi, pronounced /ˌdɛnɛb ælˈdʒiːdiː/; the traditional name of the system.
Delta Capricorni is positioned 2.6 degrees south of the ecliptic and can be occulted by the Moon, and (rarely) by planets.