The distribution of activity on the RS CVn-type star SZ Piscium.
EATON J.A. and HENRY G.W.
Abstract (from CDS):
We use contemporaneous spectra and BV light curves to derive a model of the distribution of spots and active regions on the cooler component of SZ Psc for the 1993-1994 season. For that epoch, both spots and active regions were visible at all rotational phases of this chromospherically active star. The lack of large distortions of Doppler profiles of optical lines argues for ≳15 spots with angular radii of ≲8°-10°. Transition region emission was constant to within ±12% over the orbit, nor was it eclipsed appreciably. This leads us to estimate that there are at least 20 active regions, perhaps several hundred. Chromospheric Mg II emission seems to have been proportional to the unspotted area of the star, not to the area of spots visible. We detected one strong flare in transition region lines during this program. We also present new light-curve and radial velocity solutions. These solutions find the more massive, cool star very close to its Roche lobe, and the hot star rotating more slowly than synchronously, making SZ Psc an important system for tecent he structure and evolution of binary stars. Changes in the radial velocities over 2 years of subsequent monitoring show that SZ Psc is a triple system. Hα emission seems independent of phase on the average, but it can increase markedly for periods of a few orbital cycles.