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Star formation history (SFH) is key to understand galaxy formation and evolution. For early-type galaxies (ETGs), in particular, their SFHs also record their quenching scenarios. Using stellar alpha-to-iron abundance ratio ([alpha/Fe]) as an indicator of star formation timescale (t_SF), I will present our work on the [alpha/Fe]-velocity dispersion relation of ETGs that extends to low masses with a range of dataset, and show a mass-dependent t_SF for most ETGs across a wide mass range on average, where more massive ETGs have shorter t_SF. However, the [alpha/Fe] of low-mass galaxies from the highest- and lowest-density environments in the sample are more dependent on environments than galactic masses. The data are from Gemini/GMOS-IFU observations, the literature, and the MaNGA survey. These results are further supported by a study of globular cluster specific frequency of ETGs using the HST/ACS Virgo and Fornax Cluster Surveys. |
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