RW Cephei
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Star RW Cephei |
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| Position of RW Cephei (on the left edge of the picture) | |||||||||||||||
| AladinLite | |||||||||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Cepheus | ||||||||||||||
| Right ascension | 22 h 23 m 7.02 s | ||||||||||||||
| declination | + 55 ° 57 ′ 47.6 ″ | ||||||||||||||
| Apparent brightness | 6.65 (6.0 to 7.3) mag | ||||||||||||||
| Typing | |||||||||||||||
| B − V color index | (2.22) | ||||||||||||||
| U − B color index | (2.38) | ||||||||||||||
| R − I index | (1.16) | ||||||||||||||
| Spectral class | G8 Iav | ||||||||||||||
| Variable star type | SRD | ||||||||||||||
| Astrometry | |||||||||||||||
| Radial velocity | (−56.0 ± 5.7) km / s | ||||||||||||||
| parallax | (0.24 ± 0.09) mas | ||||||||||||||
| distance | (14,000) ly (4,200) pc |
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| Proper movement | |||||||||||||||
| Rec. Share: | (−3.62 ± 0.15) mas / a | ||||||||||||||
| Dec. portion: | (−2.35 ± 0.15) mas / a | ||||||||||||||
| Physical Properties | |||||||||||||||
| Dimensions | ~ 40 M ☉ | ||||||||||||||
| radius | ~ 1400 R ☉ | ||||||||||||||
| Luminosity |
~ 500,000 L ☉ |
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Other names and catalog entries |
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RW Cephei is a hypergiant . It is the brightest star in the stellar association Cep OB1, which can be found in the constellation Cepheus in the northern hemisphere.
RW Cephei forms an apparent double star with the multiple star system SU Lacertae, but it is located at a much greater distance.
Surname
The first part of the name "RW" follows the rules for naming variable stars and says that RW Cephei is the fifteenth variable star discovered in the constellation Cepheus. The second part of the name "Cephei" corresponds to the genitive of the Latin name of the constellation Cepheus.
Physical Properties
RW Cephei probably belongs to a late G-spectral type (G8 Ia) or early K-type (K Ia). RW Cephei is a hypergiant and one of the brightest stars ever. The mass of RW Cephei is approx. 40 solar masses. Such stars use up their nuclear fuel early, they are only a few million years old before they explode as a supernova or a hypothetical hypernova and finally end up as pulsars or neutron stars or even as black holes .
The variable star RW Cephei is one of the semi-regularly variable (semi -regular stars).
Web links
- The brightest stars
- IRAS observations of the cool galactic hypergiants (English) bibcode : 1985Obs ... 105..229S
- Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way (English) bibcode : 1978ApJS ... 38..309H
- Spektrum.de : Amateur recordings [6]