We investigate, numerically, the spectrophotometric evolution of galaxies with a variety of different star formation histories and degrees of dust extinction in order to elucidate the origin of the ``red--Hδ strong'' (RHDS) galaxies -- characterised by strong [EW(Hδ)>3Å] Balmer-line absorption but with colours as red as the dormant E/S0 systems -- first observed in distant clusters of galaxies. Specifically, we investigate the evolution in the [(B-R), EW(Hδ)]--plane of two different galaxy models: a ``truncation'' model in which a galaxy with a declining star formation rate (typical of a normal spiral) has its star formation abruptly truncated, and a ``starburst'' model in which a galaxy undergoes a secondary burst of star formation which is abruptly halted. By comparing our numerical results with recent HST-based morphological and ground-based spectroscopic studies of distant cluster galaxies, we propose that there are two different evolutionary paths for the transformation of cluster spirals into S0s.
8th Asian-Pacific Regional Meeting, Volume II
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