EE Cephei
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Double star EE Cephei |
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| AladinLite | |||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Cepheus | ||||||||
| Right ascension | 22 h 09 m 22.76 s | ||||||||
| declination | + 55 ° 45 ′ 24.3 ″ | ||||||||
| Apparent brightness | +10.9 mag | ||||||||
| Typing | |||||||||
| B − V color index | +0.2 | ||||||||
| U − B color index | −0.2 | ||||||||
| Spectral class | B5: nev | ||||||||
| Variable star type | unusual occultation changeable |
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| Astrometry | |||||||||
| parallax | (0.50 ± 0.03) mas | ||||||||
| distance | 6,500 ly 2,000 pc |
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| Proper movement | |||||||||
| Rec. Share: | (−2.83 ± 0.05) mas / a | ||||||||
| Dec. portion: | (−2.50 ± 0.05) mas / a | ||||||||
| Physical Properties | |||||||||
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Other names and catalog entries |
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EE Cephei ( EE Cep for short ) is an unusual star system that presumably consists of a Be star that is surrounded by a very faint object that is in turn surrounded by a disk of dust . The latter is the most plausible interpretation of characteristic, periodic decreases in brightness, which may vary between approximately 0.5 and 2.0. This constellation of an eclipsing star is very rare and unusual.
The main star has a very high rotation speed, which should be close to the critical upper limit. The resulting, strongly ovoid shape of the star leads to an uneven distribution of the radiation flux densities over the surface (Von Zeipel theorem / gravity darkening). Seen from Earth, the darker companion covers the Be star with a period of 5.6 years. The shape of the brightness drops to be observed and the variable darkening, which is almost independent of the observed wavelength range, can best be explained by the fact that the companion is surrounded by a dust disc precessing against the orbit axis (similar to Epsilon Aurigae ). Due to the precession, other parts of the star are covered by the disk.
Table of coverages
| cover | year | Duration | Ref |
| −1 | 1947 | ||
| 0 | 1952 | ≈ 40 days | |
| 1 | 1958 | ||
| 2 | 1964 | ||
| 3 | 1969 | ≈ 60 days | |
| 4th | 1975 | ||
| 5 | 1980 | ||
| 6th | 1986 | ||
| 7th | 1992 | ≈ 1 month | |
| 8th | 1997 | ≈ 1 month | |
| 9 | 2003 | ≈ 44 days | |
| 10 | 2009 | ≈ 90 days | |
| 11 | 2014 |
Individual evidence
- ↑ a b c d e f g BD + 55 2693. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed on November 12, 2018 .
- ↑ EE Cep. In: VSX. AAVSO, accessed November 12, 2018 .
- ↑ C.Gałan et al .: International observational campaigns of the last two eclipses in EE Cephei: 2003 and 2008/9 . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1205.0028v1 .
- ↑ a b c d e f C.Gałan et al .: The 2014 Eclipse Of EE Cep: Announcement for a third international observational campaign . 2014, arxiv : 1407.1541 .
- ↑ a b c d e The start of the 2003 eclipse of EE Cephei
- ^ The next minimum of the long period eclipsing binary EE Cep
- ↑ 1980 ECLIPSE OF EE CEPHEI: LIGHT CURVES AND TIME OF MINIMUM
- ↑ Is the eclipsing variable EE Cep a cousin of ε Aur?
- ^ The 2008/2009 eclipse of EE Cep - short guide for photometric observations.