Hot/cool spots observed in the ANS ultraviolet light curves of U Cephei.
Abstract
Ultraviolet light curves of the interacting eclipsing binary U Cephei, reported to have been undergoing major outbursts in 1974 through 1975, were obtained in 1975 with the Astronomical Netherlands Satellite (ANS) ultraviolet photometers. A 21 data-point light curve was obtained at each of the 1550, 1800, 2200, 2500, and 3300 A wavelength regions. Two very unusual features have been noted in the light curves: (1) the second maximum light at phase 0.75 is decidedly brighter than the first maximum at phase 0.25 by a factor of about 1.3-1.8; (2) the secondary minimum is displaced, from phase 0.5 to 0.6 in all of the light curves and is deeper at shorter wavelengths, contrary to what might be expected in an eclipsing binary consisting of two normal stars radiating approximately in a Planckian fashion. This anomalous behavior in the light curves may be explained in terms of a hot spot on the trailing side of the B component and a 'lesser' hot spot on the trailing side of the G component, both of which result from the impacting gas streams in this binary.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1978
- DOI:
- 10.1086/156180
- Bibcode:
- 1978ApJ...222..635K
- Keywords:
-
- Astronomical Netherlands Satellite;
- Eclipsing Binary Stars;
- Light Curve;
- Stellar Radiation;
- B Stars;
- Emission Spectra;
- Satellite Observation;
- Stellar Envelopes;
- Stellar Mass Ejection;
- Stellar Models;
- Stellar Spectra;
- Stellar Temperature;
- Ultraviolet Spectra;
- Astrophysics;
- Eclipsing Binaries:Light Curves;
- Eclipsing Binaries:Starspots