An analysis is presented of high-resolution high SNR spectra of late-type chromospherically active dwarfs in Ca II H. 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

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The revised physical assumptions incorporated into a previously published evolutionary model for stellar population synthesis in galaxies (Casuso et al., 1989) are outlined. Applying the present version of the model to well defined zones on the nucleus and along a spiral arm of NGC 2903, it is shown that the star-formation rate has increased during

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We present some preliminary results of a spectroscopic study of the cataclysmic system IR Gem at quiescence during two orbital periods. The spectra covered the wavelength range 4000 7000 Å. The variations with the phase in the equivalent width of the Hα line confirms the existence of a maximum at phase 0.5.

The detection of high late-time luminosity in the type-II plateau supernova 1988A about 500 days after maximum indicates that some mechanism is still providing large amounts of energy to the supernova at this very late phase. We present a review of the observations of this supernova at different phases, and examine the possible mechanisms that can