Alpha Delphini
Multiple star system in the constellation Delphinus / From Wikipedia, the free encyclopedia
For the racehorse, see Alpha Delphini (horse).
Alpha Delphini (α Delphini, abbreviated Alpha Del, α Del) is a multiple star system in the constellation of Delphinus.
Quick Facts Observation data Epoch J2000.0 Equinox J2000.0, Constellation ...
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Delphinus |
Right ascension | 20h 39m 38.28720s[1] |
Declination | +15° 54′ 43.4637″[1] |
Apparent magnitude (V) | +3.777[2] (3.86 + 6.43[3]) |
Characteristics | |
Spectral type | B9 IV[4] |
U−B color index | −0.205[2] |
B−V color index | −0.061[2] |
Astrometry | |
Radial velocity (Rv) | −3.40[5] km/s |
Proper motion (μ) | RA: 53.82 ± 0.43[1] mas/yr Dec.: 8.47 ± 0.31[1] mas/yr |
Parallax (π) | 12.85 ± 0.44 mas[1] |
Distance | 254 ± 9 ly (78 ± 3 pc) |
Absolute magnitude (MV) | −0.4[6] |
Orbit[7] | |
Primary | Aa (A) |
Companion | Ab (B) |
Period (P) | 6175.3±3.2 d |
Semi-major axis (a) | 0.15809±0.00013" (12.7±0.4 AU) |
Eccentricity (e) | 0.4615±0.0016 |
Inclination (i) | 161.01±0.30° |
Longitude of the node (Ω) | 120.62±1.19° |
Periastron epoch (T) | JD57988.7 |
Argument of periastron (ω) (secondary) | 91.73±1.09° |
Orbit | |
Primary | Ab1 (Ba) |
Companion | Ab2 (Bb) |
Period (P) | 29.9873±0.0021 d |
Semi-major axis (a) | 0.0003587±0.000010" (0.281±0.008 AU) |
Eccentricity (e) | 0.0761±0.0012 |
Inclination (i) | 22.11±0.61° |
Longitude of the node (Ω) | 359.97±0.65° |
Periastron epoch (T) | JD58762.84 |
Argument of periastron (ω) (secondary) | 166.43±1.27° |
Semi-amplitude (K2) (secondary) | 21.19±0.18 km/s |
Details | |
Aa (A) | |
Mass | 3.83±0.33[7] M☉ |
Radius | 3.92[8] R☉ |
Surface gravity (log g) | 3.93[9] cgs |
Temperature | 11,643[9] K |
Rotational velocity (v sin i) | 144[9] km/s |
Age | 227[9] Myr |
Ab1 (Ba) | |
Mass | 1.82±0.15[7] M☉ |
Ab2 (Bb) | |
Mass | 1.49±0.12[7] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
Close
It consists of a triple star, designated Alpha Delphini A, together with five faint, probably optical companions,[10][11] designated Alpha Delphini B, C, D, E and F. A's two components are themselves designated Alpha Delphini Aa (officially named Sualocin /ˈswɒloʊsɪn/, the historical name for the entire system)[12][13] and Ab.[10]