Beta Capricorni
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Capricornus |
| β1 Cap | |
| Right ascension | 20h 21m 00.6666s |
| Declination | −14° 46′ 53.067″ |
| Apparent magnitude (V) | +3.05 |
| β2 Cap | |
| Right ascension | 20h 20m 46.5479s |
| Declination | −14° 47′ 05.604″ |
| Apparent magnitude (V) | +6.09 |
| Characteristics | |
| β1 Cap | |
| Spectral type | K0II+B8V |
| U−B color index | +0.27 |
| B−V color index | +0.79 |
| β2 Cap | |
| Evolutionary stage | main sequence |
| Spectral type | A0III |
| U−B color index | −0.11 |
| B−V color index | −0.02 |
| Astrometry | |
| β1 Cap | |
| Radial velocity (Rv) | −19.0±0.6 km/s |
| Proper motion (μ) | RA: +44.133 mas/yr Dec.: +0.360 mas/yr |
| Parallax (π) | 8.3966±0.6348 mas |
| Distance | 390 ± 30 ly (119 ± 9 pc) |
| Absolute magnitude (MV) | −2.03 |
| β2 Cap | |
| Proper motion (μ) | RA: +44.411 mas/yr Dec.: −0.637 mas/yr |
| Parallax (π) | 9.8983±0.3071 mas |
| Distance | 330 ± 10 ly (101 ± 3 pc) |
| Absolute magnitude (MV) | +1.03 |
| Orbit | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 3.762 yr |
| Semi-major axis (a) | 0.049″ |
| Eccentricity (e) | 0.452 |
| Inclination (i) | 75.1° |
| Semi-amplitude (K1) (primary) | 22.4 km/s |
| Semi-amplitude (K2) (secondary) | 19.6 km/s |
| Orbit | |
| Primary | Ab1 |
| Name | Ab2 |
| Period (P) | 8.677 days |
| Eccentricity (e) | 0.340 |
| Semi-amplitude (K1) (primary) | 35.1 km/s |
| Orbit | |
| Primary | Ba |
| Name | Bb |
| Period (P) | 400 yr |
| Semi-major axis (a) | 0.689″ |
| Eccentricity (e) | 0.458 |
| Inclination (i) | 125.2° |
| Details | |
| β1 Cap Aa | |
| Mass | 3.69±0.20 M☉ |
| Radius | 31.4 R☉ |
| Luminosity | 501 L☉ |
| Temperature | 4,870 K |
| Age | 230 Myr |
| β Cap Ab1 | |
| Mass | 4.22 M☉ |
| Luminosity | 112 L☉ |
| Age | 230 Myr |
| β Cap Ab2 | |
| Mass | 0.94 M☉ |
| Age | 230 Myr |
| β Cap Ba | |
| Mass | 2.53 M☉ |
| Radius | 1.98 R☉ |
| Luminosity | 55 L☉ |
| Surface gravity (log g) | 4.18 cgs |
| Temperature | 11,188 K |
| Age | 230 Myr |
| β Cap Bb | |
| Mass | 1.23 M☉ |
| Age | 230 Myr |
| Other designations | |
| Dabih, β Cap, 9 Capricorni, FK5 762, WDS J20210-1447AB | |
| β1 Cap: Dabih Major, BD−15°5629, HD 193495, HIP 100345, HR 7776, WDS J20210-1447A | |
| β2 Cap: Dabih Minor, BD−15°5626, HD 193452, HIP 100325, HR 7775, WDS J20210-1447B | |
| Database references | |
| SIMBAD | β1 Cap |
| β2 Cap | |
Beta Capricorni is a multiple star system in the constellation of Capricornus. Its name is a Bayer designation that is Latinized from β Capricorni, and abbreviated Beta Cap or β Cap. Based on Parallax measurements, it is located at a distance of approximately 390 light years from the Sun. The system is drifting closer with a line of sight velocity of −19 km/s. Because it is positioned near the ecliptic, Beta Capricorni can be occulted by the Moon, and also (rarely) by planets.
The system is believed to consist of five stars. With binoculars or a small telescope, Beta Capricorni can be resolved into a binary pair. The brighter of the two is designated Beta1 Capricorni or Beta Capricorni A; the dimmer, Beta2 Capricorni or Beta Capricorni B. Both are themselves made up of multiple stars. Beta1 Capricorni has three components: a single star designated Beta Capricorni Aa (formally named Dabih /ˈdeɪbiː/, the traditional name of the system) and a binary pair, Beta Capricorni Ab (whose two components are designated Beta Capricorni Ab1 and Ab2). Beta2 Capricorni is also a binary pair, with components designated Beta Capricorni Ba and Bb.
Two other nearby stars were discovered by John Herschel. Sometimes referred to as Beta Capricorni D and E, it is unclear whether they are simply optical doubles or part of the Beta Capricorni system.