RW Cephei
 Position of RW Cephei |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 23m 07.01657s[1] |
| Declination | +55° 57′ 47.6262″[1] |
| Apparent magnitude (V) | +6.59[2] |
| Characteristics | |
| Spectral type | K20-Ia[3] |
| Apparent magnitude (K) | 1.88[4] |
| U−B color index | 2.38[4] |
| B−V color index | 2.22[4] |
| Variable type | SRd[5] |
| Astrometry | |
| Radial velocity (Rv) | -56.00[6] km/s |
| Proper motion (μ) | RA: -2.74[1] mas/yr Dec.: -2.66[1] mas/yr |
| Parallax (π) | 0.81 ± 0.36[1] mas |
| Distance | 3,500[7] pc |
| Absolute magnitude (MV) | -9.4[7] |
| Details | |
| Radius | 1,535[7][8] R☉ |
| Luminosity | 550,000[7] L☉ |
| Temperature | 4,015[8] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
RW Cephei is an orange hypergiant star in the constellation Cepheus. One of the largest stars known, RW Cephei is estimated at 1,535 solar radii, which is larger than the orbit of Jupiter.
RW Cephei is also a semi-regular variable star of type SRd, meaning that it is a slowly varying yellow giant or supergiant. Its surface is subject to pulsations in temperature and luminosity. Over the past 50 to 70 years it has varied from classes G8 to M0 with no discernible pattern.[9] Despite its variable spectral type, it has been listed as a spectral standard star for type "K2 0-Ia".[3]
The distance to RW Cephei has been estimated on the basis of its spectroscopic luminosity and is assumed to be a member of the Cepheus OB1 association at 3,500 parsecs. This is several times further than the distance implied by the Hipparcos parallax, although the apparent diameter of the star is larger than the measured parallax and variable.[9][2]
The temperature intermediate between the red supergiants and yellow hypergiants, and itself varying considerably, has led to it being variously considered as a red hypergiant or [10] or yellow hypergiant.[11]
References
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- ↑ 2.0 2.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 4.2 Lua error in package.lua at line 80: module 'strict' not found.
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See also
| <<< 7. VV Cephei A | 9. KY Cygni/VY Canis Majoris >>> |
