On the origin of S0 stellar populations - Can S0s form with secondary starbursts?

We investigate a one-zone chemo-photometric evolutionary model of truncated spiral galaxies with and without starbursts in order to explore the origin of the spectrophotometric properties of S0s. First, we show that 1) the ti ght U-V colour-magnitude (CM) relation cannot reject the model with a starb urst and 2) the model with a starburst can explain the difference in the I- K colour-magnitude relation between S0 galaxies and spiral galaxies. Next, we demonstrate how we can distinguish the truncated spirals with a starburs t from those without a starburst by using the CaII-H delta/lambda 4045 diag ram (proposed by Leonardi and Rose, 1996) and the 1550-V colour.