U Cephei
 U Cephei, as seen during the Digitized Sky Survey | |
| Constellation | Cepheus |
|---|---|
| Coordinates |
|
| Distance | 825.73 ly (253.16 pc) |
| Epoch | J2000 |
| Characteristics | |
| Apparent m | 6.9 |
| Spectral type | G8III |
| Planets | 0 |
| Orbit | |
| Eccentricity | 0.07560 |
U Cephei is an eclipsing binary star discovered in 1880.[1][2] It consists of a blue-white main sequence star of spectral type B7Ve that is eclipsed every two and a half days by a less bright giant of type G8III-IV.[3] The drop in brightness lasts 4 hours and the system sees its apparent magnitude increase from 6.7 to 9.2. The total eclipse then lasts 2 hours before an increase in brightness for 4 hours. The two stars, separated by less than 10,000,000 kilometres (6,200,000 mi), exchange matter. This transfer towards the blue giant caused the system's orbital period to lengthen by 4 minutes during the 20th century. U Cephei is one of the brightest eclipsing binaries. Located near the north celestial pole, it can be monitored continuously with a 60 millimeter telescope.[3]
The system has two visual companions listed in the double and multiple star catalogs. U Cephei B is a twelfth magnitude star that, as of 2016, was located at an angular distance of 13.9 arcseconds and at a position angle of 63° from U Cephei A. It exhibits a common proper motion with the system, which indicates that it is physically linked to it. U Cephei C is another twelfth magnitude star, but it is only a purely optical double and its proximity to the system is a coincidence.[5]
See also
References
- ^ "U Cephei | astronomy | Britannica". www.britannica.com. Retrieved 2024-09-27.
- ^ Gimenez, A.; Guinan, E. F.; Gonzalez-Riestra, R. (1993-01-01). "UV and X-ray emission in the interacting binary U Cephei". Astronomy and Astrophysics Supplement Series. 97 (1). ISSN 0365-0138.
- ^ a b "U Cephei Star Facts - Universe Guide". www.universeguide.com. January 25, 2015. Retrieved 2024-09-27.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 1 October 2024.
- ^ Knott, George (June 9, 1882). "On the Variable Star U Cephei". Monthly Notices of the Royal Astronomical Society. Retrieved September 27, 2024.
