Summary: ON THE BELIEVABILITY OF POLAR SPOTS
P. BRENDAN BYRNE
Armagh Observatory
College Hill, Armagh BT61 9DG, N. Ireland
Abstract. Polar spots in Doppler Imaging maps of rapidly rotating late­
type stars, especially the active components of RSCVn binaries, represent
a major break with the solar paradigm, within which spots are only found
at low latitudes. I examine critically the evidence for polar spots and point
out that they are particularly sensitive to a number of systematic effects
relating to determining reference ``zero­points''.
1. Introduction
The technique of Doppler Imaging offers the potential to resolve in some
detail spot distributions on active late­type stars. Since the seminal paper
by Vogt and Penrod (1983) which imaged the spot distribution on the
RSCVn star, V411Tau (=HR1099), almost all such images have shown a
dark polar cap. These have been attributed to large­scale spots including
a symmetric distribution at the stellar pole.
Such spot distributions represent a fundamental break with the solar
paradigm, in which spots are always found at latitudes between ¸10 ffi --40 ffi .
Of course, in view of the very great difference in magnetic activity between

Source: Armagh Observatory

Collections: Physics