Direct Evidence for a Polar Spot on SV Cam

Abstract

We have used spectrophotometric data from the Hubble Space Telescope to eclipse-map the primary component of the RS CVn binary SV Cam over 9 HST orbits. We find from these observations and the HIPPARCOS parallax that the surface flux in the eclipsed low-latitude region of the primary is about 30% lower than computed from a PHOENIX model atmosphere at the effective temperature that best fits the spectral energy distribution of the eclipsed flux. This can only be accounted for if about a third of the primary's surface is covered with unresolved dark star-spots. Extending this to the full surface of the primary, we find that even taking into account this spot filling factor there is an additional flux deficit on the primary star. This can only be explained if there is a large polar spot on the primary star extending from the pole to latitude 48 degrees.

20 pages, 14 figures, accepted by ApJ

Cited by in corpus (8)

• Evolution of low-mass star and brown dwarf eclipsing binaries
• Magnetic activity on AB Doradus: Temporal evolution of starspots and differential rotation from 1988 to 1994
• Spurious 'active longitudes' in parametric models of heavily spotted eclipsing binaries
• Hubble Space Telescope Observations of SV Cam: I. The Importance of Unresolved Starspot Distributions in Lightcurve Fitting
• Star-spot distributions and chromospheric activity on the RS CVn type eclipsing binary SV Cam
• Pulsating Components in Binary and Multiple Stellar Systems --- A Catalog of Oscillating Binaries
• Hubble Space Telescope Observations of SV Cam: II. First Derivative Lightcurve Modelling using PHOENIX and ATLAS Model Atmospheres
• X-ray Evidence for a Pole-Dominated Corona on AB Dor