Beta Delphini
Beta Delphini (β Delphini, abbreviated Beta Del, β Del) is a binary star in the constellation of Delphinus. It is the brightest star in Delphinus.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 37m 32.94130s |
| Declination | +14° 35′ 42.3195″ |
| Apparent magnitude (V) | 3.617±0.016 (4.11 + 5.01) |
| Characteristics | |
| Spectral type | F5 III + F5 IV |
| B−V color index | A: 0.43±0.14 B: 0.56±0.25 |
| Astrometry | |
| Beta Delphini A | |
| Proper motion (μ) | RA: +118.09 mas/yr Dec.: -48.06 mas/yr |
| Parallax (π) | 32.33 ± 0.47 mas |
| Distance | 101 ± 1 ly (30.9 ± 0.4 pc) |
| Absolute magnitude (MV) | 1.58±0.12 |
| Beta Delphini B | |
| Absolute magnitude (MV) | 2.79±0.14 |
| Orbit | |
| Period (P) | 26.660 yr |
| Semi-major axis (a) | 0.440″ |
| Eccentricity (e) | 0.36 |
| Inclination (i) | 61° |
| Longitude of the node (Ω) | 177° |
| Periastron epoch (T) | 1989.50 yr |
| Argument of periastron (ω) (secondary) | 349° |
| Semi-amplitude (K1) (primary) | 7.6 km/s |
| Details | |
| Beta Delphini A | |
| Mass | 1.75±0.002 M☉ |
| Luminosity | 24 L☉ |
| Surface gravity (log g) | 3.50 cgs |
| Temperature | 6587 K |
| Metallicity [Fe/H] | –0.05 dex |
| Rotational velocity (v sin i) | 49.8 km/s |
| Age | 1.79+0.17 −0.72 Gyr |
| Beta Delphini B | |
| Mass | 1.47±0.04 M☉ |
| Luminosity | 8 L☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The two components of the system are designated Beta Delphini A (officially named Rotanev /ˈroʊtənɛv/, which is historically the name of the system) and B.
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