Starspots as the cause of the intrinsic light variations in RS Canum Venaticorum type stars
We have used a theoretical model of a binary system in which one of the components has spots on its surface to interpret the light curves of three well-observed RS CVn type systems, RS CVn, SZ Psc, and RT Lac. The first two of these are detached while the third is presently semidetached. We find that by using this spot model it is possible to fit in detail both the out-of-eclipse complications and the distorted shapes of the secondary eclipses in the light curves of these stars and that the spot model gives significantly better results than any competing hypothesis for the origin of the light curv peculiarities.The surface activity in RS CVn type stars has many of the properties of solar activity. These objects undergo true spot cycles, cycles in which the number of spots and with it the spotted star's luminosity varies, on time scales only somewhat longer (2--3 times) than the 11 year solar cycle. Individual spots are significantly smaller than the spotted star's disk and have lifetimes of less than 1 year. They seem to extend over a sizable range of latitude, at least 15/sup 0/ in both hemispheres for RS CVn and RT Lac. The spots are cooler than the surrounding photosphere, by at least 400 K for all three stars and 1200 K for one, and seem to be associated with the magnetic fields inferred from the polarization of radio emissions of flares and from chromospheric line emissionThe surface activity of these stars, though, appears to be more highly organized than that of the sun. The spatial distributions of spots indicate a global organization of the magnetic field structure and the mechanism producing it. Regions of enhanced mass loss, analogous to solar coronal holes, occur around the longitude of minimum spot concentration. Variations in the rate of migration in longitude of the spot distribution indicate that the rotation rate of the sources of the field depends on the phase of the spot cycle.
- Research Organization:
- Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center
- OSTI ID:
- 6470619
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 227:3; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BINARY STARS
ECLIPSE
MAGNETIC FIELDS
MATHEMATICAL MODELS
PHOTOMETRY
PULSATIONS
SOLAR ACTIVITY
STAR MODELS
STARS
STELLAR ATMOSPHERES
SUNSPOTS
VARIATIONS