LINE-PROFILE ASYMMETRIES IN CHROMOSPHERICALLY ACTIVE STARS

A powerful, new probe of chromospheric activity-cross-correlation-has been developed and applied to a variety of stars. In this particular application, an entire CCD spectrum of an active star is correlated with the spectrum of a narrow-line, inactive star of similar spectral type and luminosity class. Using a number of strong lines in this manner enables the detection of absorption profile asymmetries at moderate resolution (lambda/DELTA-lambda approximately 40,000) and S/N 150:1. This technique has been applied to 14 systems mostly RS CVn's, with 10 less-than-or-equal-to v sin i less-than-or-equal-to 50 km s-1 and P greater-than-or-equal-to 7d. Distortions were detected for the first time in five systems: sigma-Gem, IM Peg, GX Lib, UV Crb, and zeta And. Detailed modeling, incorporating both spectral line profiles and broad-band photometry, is applied to sigma-Gem. Profile asymmetries for this star are fitted by two high-latitude spots covering 5% of the stellar surface. The derived spot temperature of 3400 K is lower than found in previous studies. In addition, two well-known systems have been studied: HD 199178 and V711 Tau. Polar spots are found on