V636 Scorpii
Spectroscopic binary star system in the constellation Scorpius / From Wikipedia, the free encyclopedia
V636 Scorpii is a multiple star system in the constellation Scorpius, 3,000 light years away. The primary is a Classical Cepheid (δ Cephei) variable and its visual magnitude varies from 6.4 to 6.9.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Scorpius |
Right ascension | 17h 22m 46.47796s[2] |
Declination | −45° 36′ 51.3868″[2] |
Apparent magnitude (V) | 6.40 - 6.92[3] |
Characteristics | |
Cepheid | |
Spectral type | F7/8Ib/II-G5[3] |
Variable type | δ Cep[3] |
companion | |
Spectral type | B9.5V[4] |
Astrometry | |
Radial velocity (Rv) | 9.09 ± 0.17[5] km/s |
Proper motion (μ) | RA: -3.05 ± 1.03[2] mas/yr Dec.: -2.40 ± 0.38[2] mas/yr |
Parallax (π) | 1.15 ± 0.76 mas[2] |
Distance | approx. 3,000 ly (approx. 900 pc) |
Absolute magnitude (MV) | -3.64[4] |
Orbit | |
Period (P) | 1,318 days[4] |
Semi-major axis (a) | 6.7[4] |
Eccentricity (e) | 0.26[6] |
Details | |
Cepheid | |
Mass | 5.6[4] M☉ |
Radius | ~50[7] R☉ |
Luminosity | 2,500[4] L☉ |
Metallicity | +0.07[8] |
companion | |
Mass | 2.4 M☉ |
Other designations | |
Database references | |
SIMBAD | data |
V636 Scorpii is a spectroscopic binary, and the fainter companion is thought to itself consist of two stars. The primary is a luminous yellow star and a δ Cephei variable. The less massive companion orbits every 3.6 years and is apparently a B9.5 main sequence star, but the dynamics of the system suggest that it may actually be a pair of stars is a close orbit.[9]
The Cepheid primary pulsates regularly with a period of 6.79671 days. It is a yellow-white supergiant or bright giant that is 5.6 times as massive as the Sun and 2,500 times as luminous.[4]