A Chronology of Star Spots on CK Bo\"otis

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Session 85 -- Interacting Binaries: ``Normal'' Stars
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[85.06] A Chronology of Star Spots on CK Bo\"otis

N.L. Markworth (SF Austin St. Un.)

The W UMa system CK Bo\"otis has eclipses of almost equal depth, which periodically interchange roles, the primary eclipse being the deeper eclipse in some seasons, the shallower in other. We have reanalyzed the light curves of Aslan and Derman (1986), which were obtained seasonally in 1976, 1977, 1978, 1981, and 1982, along with the light curves of Gann (1986), obtained in 1985, and Luther(unpublished) in 1991. We have taken the 1977 light curve to represent a situation in which CK Boo is as undisturbed as is possible and have used it to obtained to geometrical and astrophysical parameters of the system using the revised code of Wilson (1992). It was necessary to introduce a cool spot on the surface of the primary star in order to account for a small O'Connell effect. The other light curves were then fitted by adjusting spot parameters or adding spots as necessary. Each seasonal light curve can be successfully represented in this manner.

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