Chromospherically Active Stars in the Galactic Bulge

We present the results from the discovery and study of ~3000chromospherically active giant and subgiant stars toward the Galactic bulge. Wefind that these stars are predominantly RS CVn binaries with rotation periodsbetween 10 and 100 days. We discover that the average rotational period ofthese stars decreases with their distance from the Galactic plane. We find thatthe primary stars in the RS CVn systems are predominantly first-ascent giants.Our research also suggests that, if these stars have spot cycles like the sun,then the cycle period must be longer than 10 years on average. We confirm thatthe amplitude of the spot-induced modulations observed in the light curves ofthese objects is generally larger at minimum light than at maximum.Furthermore, we confirm that the amplitudes of the modulations due to stellarspots generally increases as the observed change in average brightnessincreases. We find no evidence for a relationship between a CA star'sbrightness and its rotational period. However, the average period does increasewith colour for stars with periods >~30 days.Comment: Accepted AJ. 18 pages, 17 figures (at low resolution to meet astro-ph file size requirements