Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cepheus |
Right ascension | 22h 36m 27.56307s [2] |
Declination | +58° 25′ 33.9554″ [2] |
Apparent magnitude (V) | 6.83 - 9.20 [3] |
Characteristics | |
Evolutionary stage | Red supergiant + non-supergiant B class star |
Spectral type | K0ep-M2ep Ia + B0/B1 [3] |
Variable type | SRc [3] |
Astrometry | |
Radial velocity (Rv) | −44.64 [4] km/s |
Proper motion (μ) |
RA: −3.176
[2]
mas/
yr Dec.: −2.277 [2] mas/ yr |
Distance | 2,427 [5] pc |
Absolute magnitude (MV) | −7 [6] + −3.5 [7] |
Orbit [8] | |
Period (P) | 2,075 d |
Eccentricity (e) | 0.149 |
Inclination (i) | 90° |
Details | |
Radius | 666; [2] R☉ |
Luminosity | 292,000 [9] L☉ |
Surface gravity (log g) | 0.18 [2] cgs |
Temperature | 3,681 [9] – 4,400 [10] 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. [5] [11] The supergiant primary star is one of the largest known stars and as well as one of the most luminous red supergiants.
W Cephei was catalogued as BD+57°2568 in the Bonner Durchmusterung published in 1903, and HD 214369 in the Henry Draper Catalogue. It reported in 1896 as a red star varying from magnitude 7.3 to 8.3. [12]
In 1925, W Cep was included in a listing of Be stars. It was recognised as a cool star with spectral type Mep. [13] It was classified as K0ep Ia from a 1949 spectrum, but also recognised to have a small hot companion, plus an unusual infrared excess. [14] [15] Ultraviolet spectra allowed absorption lines from the companion to be studied and it was given a spectral type of B0-1. [16]
The W Cephei system contains a luminous red 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. [6] The two components have been resolved at 0.262 ″ using speckle interferometry. [17] An orbital period of 2,090 days has been proposed. [11]
W Cephei varies in brightness from 7th to 9th magnitude. The General Catalogue of Variable Stars lists it as a semiregular variable with a period of 370 days, but later attempts to find a period have shown only random variations. [18] [19] It has also been proposed that eclipses occur. [20]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cepheus |
Right ascension | 22h 36m 27.56307s [2] |
Declination | +58° 25′ 33.9554″ [2] |
Apparent magnitude (V) | 6.83 - 9.20 [3] |
Characteristics | |
Evolutionary stage | Red supergiant + non-supergiant B class star |
Spectral type | K0ep-M2ep Ia + B0/B1 [3] |
Variable type | SRc [3] |
Astrometry | |
Radial velocity (Rv) | −44.64 [4] km/s |
Proper motion (μ) |
RA: −3.176
[2]
mas/
yr Dec.: −2.277 [2] mas/ yr |
Distance | 2,427 [5] pc |
Absolute magnitude (MV) | −7 [6] + −3.5 [7] |
Orbit [8] | |
Period (P) | 2,075 d |
Eccentricity (e) | 0.149 |
Inclination (i) | 90° |
Details | |
Radius | 666; [2] R☉ |
Luminosity | 292,000 [9] L☉ |
Surface gravity (log g) | 0.18 [2] cgs |
Temperature | 3,681 [9] – 4,400 [10] 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. [5] [11] The supergiant primary star is one of the largest known stars and as well as one of the most luminous red supergiants.
W Cephei was catalogued as BD+57°2568 in the Bonner Durchmusterung published in 1903, and HD 214369 in the Henry Draper Catalogue. It reported in 1896 as a red star varying from magnitude 7.3 to 8.3. [12]
In 1925, W Cep was included in a listing of Be stars. It was recognised as a cool star with spectral type Mep. [13] It was classified as K0ep Ia from a 1949 spectrum, but also recognised to have a small hot companion, plus an unusual infrared excess. [14] [15] Ultraviolet spectra allowed absorption lines from the companion to be studied and it was given a spectral type of B0-1. [16]
The W Cephei system contains a luminous red 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. [6] The two components have been resolved at 0.262 ″ using speckle interferometry. [17] An orbital period of 2,090 days has been proposed. [11]
W Cephei varies in brightness from 7th to 9th magnitude. The General Catalogue of Variable Stars lists it as a semiregular variable with a period of 370 days, but later attempts to find a period have shown only random variations. [18] [19] It has also been proposed that eclipses occur. [20]