Chromospheric variability in late-type dwarfs from high-resolution spectra of Caii H

Abstract

We present an analysis of high-resolution (λ/δλ≈8×104) high signal-to-noise-ratio spectra of late-type chromospherically active dwarfs in Caii H (λ3968.47 A), obtained with the Coude Auxiliary Telescope plus the Coude Echelle Spectrometer at ESO, La Silla. Observational parameters employed are the total emission flux attributable to the chromosphere, the asymmetry of the emission component and its bisector, the ratio of the intensities of the blue and red H2 emission peaks, and the absolute wavelengths of the H3 minimum and the mean emission feature. Given time-spaced sets of spectra for each object, which are as yet relatively sparse, we explore the potential use of these observational parameters to deepen our understanding of the chromospheric activity.