Abstract
ABSTRACT The results of a high-resolution spectroscopic synoptic program of observations of key chromospheric diagnostics in a sample of dwarf stars are reported. Low-level variability in the strength of the chromospheric H-alpha absorption line is found. The nature of the variability implies that the operative chromospheric heating mechanism is partially characterized by a transient component. This fact, combined with the detectability of the low-level variability, suggests that magnetic field-related, nonradiative atmospheric heating is widespread in the dM stars. High-amplitude variability in the H-alpha emission strength of the active dMe star BY Dra was also observed. Synoptic observations of the He I 5876 A absorption line in three solar-type stars revealed low-level variability in the strength of this feature.
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