W Cephei
| Observation data Epoch 2000 Equinox 2000 |
|
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 36m 27.56359s[1] |
| Declination | +58° 25′ 343.9456″[1] |
| Apparent magnitude (V) | 7.02 - 9.20[2] |
| Characteristics | |
| Spectral type | K0ep-M2ep Ia + B0/B1[2] |
| Variable type | SRc[2] |
| Astrometry | |
| Radial velocity (Rv) | −44.64[3] km/s |
| Proper motion (μ) | RA: −2.48[1] mas/yr Dec.: −3.27[1] mas/yr |
| Parallax (π) | 0.02 ± 0.59[1] mas |
| Distance | 2,427[4] pc |
| Absolute magnitude (MV) | −7[5] + −3.5[6] |
| Details[7] | |
| Luminosity | 72,400 L☉ |
| Temperature | 4,400 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
W Cephei is a spectroscopic binary and variable star located in the constellation Cepheus. It is thought to be a member of the Cep OB1 stellar association at about 8,000 light years.[4][8]
Discovery
W Cephei was reported in 1896 as a red star varying from magnitude 7.3 to 8.3.[9] It was catalogued as BD+57°2568 in the Bonner Durchmusterung published in 1903, and HD 214369 in the Henry Draper Catalogue.
In 1925, W Cep was included in a listing of Be stars. It was recognised as a cool star with spectral type Mep.[10] It was classified as K0ep Ia from a 1949 spectrum, but also recognised to have a small hot companion, plus an unusual infrared excess.[11][12] Ultraviolet spectra allowed absorption lines from the companion to be studied and it was given a spectral type of B0-1.[13]
System
The W Cephei system contains a K class supergiant star with a non-supergiant early B companion. The star has unusual emission lines including both permitted and forbidden FeII, produced by a circumstellar envelope containing dust and ionised gas.[5] The two components have been resolved at 0.262" using Speckle interferometry.[14] An orbital period of 2,090 days has been proposed.[8]
Variability
W Cephei varies in brightness from 7th to 9th magnitude. The General Catalogue of Variable Stars lists it as a semiregular variable but attempts to find a period have shown only random variations.[15][16]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 >Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
