On the Origin of S0 Stellar Populations

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 tight U-V colour–magnitude (CM) relation cannot reject the model with a starburst 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 starburst from those without a starburst by using the CaII–Hδ/λ4045 diagram (proposed by Leonardi and Rose, 1996) and the 1550-V colour.