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U Cephei

U Cephei is an eclipsing binary star discovered in 1880.[5][6] It consists of a blue-white main sequence star of spectral type B7/8V that is eclipsed every two and a half days by a less bright giant of type G5/8III-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.[7]

A light curve for U Cephei, plotted from TESS data. [8] The 2.493 day eclipse period is shown in red.

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.[9]

See also

References

  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b "V* U Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-02-22.
  3. ^ a b c d Tupa, Peter R.; Deleo, Gary G.; McCluskey, George E.; Kondo, Yoji; Sahade, Jorge; Giménez, Alvaro; Caton, Daniel B. (2013). "Ultraviolet Spectroscopic Analysis of Transient Mass Flow Outburst in U Cephei". The Astrophysical Journal. 775 (1): 46. Bibcode:2013ApJ...775...46T. doi:10.1088/0004-637X/775/1/46.
  4. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  5. ^ "U Cephei | astronomy | Britannica". www.britannica.com. Retrieved 2024-09-27.
  6. ^ 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): 261. Bibcode:1993A&AS...97..261G. ISSN 0365-0138.
  7. ^ "U Cephei Star Facts - Universe Guide". www.universeguide.com. January 25, 2015. Retrieved 2024-09-27.
  8. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 1 October 2024.
  9. ^ Knott, George (June 9, 1882). "On the Variable Star U Cephei". Monthly Notices of the Royal Astronomical Society. 42 (8): 384–385. doi:10.1093/mnras/42.8.384a. Retrieved September 27, 2024.