AAS 201st Meeting, January, 2003
Session 4. Eclipsing and Spectroscopic Binaries
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

[Previous] | [Session 4] | [Next]

[4.02] Ultraviolet Spectroscopic Analysis of Mass Flow in the Interacting Binary U Cephei

G.E. McCluskey, Jr., J. Johnson, G.G. DeLeo (Lehigh University), F. Bruhweiler (NASA), W. Anderson (Catholic University), Y. Kondo (NASA), A. Gimenez (ESA), E.F. Guinan (Villanova University), J. Sahade (La Plata)

Twenty-nine far-ultraviolet and forty-seven near-ultraviolet high resolution International Ultraviolet Explorer (IUE) Satellite archival spectra of the interacting Algol-type binary U Cephei ( B7 V + G8 III-IV ) have been analyzed in order to determine the nature of the variable mass flow occurring in this system. Relatively good phase coverage was obtained in 1989 with fourteen far-ultraviolet and fifteen near-ultraviolet spectra spread over 1.2 orbits. The effects of gas streaming within and out of the system and of pseudophotospheric flow on the primary star are clearly seen in the ultraviolet resonance lines of Si IV (\lambda\lambda 1393, 1402 ), CIV (\lambda\lambda 1548, 1550), Al II (\lambda 1670 ), Al III (\lambda\lambda 1854, 1862 ), Fe II (\lambda 2599 ), and Mg II (\lambda\lambda 2795, 2802 ). A major mass flow outburst occurred in 1986 and a weaker outburst appears in some of the 1989 spectra. Light curves were constructed at a number of ultraviolet wavelengths. These light curves show significant departures from those expected from quiescent eclipsing binaries. It may be concluded that U Cep, and a number of other Algol-type binaries studied elsewhere, show pseudophotospheric accretion phenomena, mass exchange and systemic mass loss with occasional, variable, short-term increases in activity.

[Previous] | [Session 4] | [Next]

Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.