Speaker
Description
In Galactic archaeology, the “alpha-knee” – where the slope of the [α/Fe]–[Fe/H] relation changes – is a chemical feature that serves as a powerful diagnostic of star formation histories in galaxies. The characteristics of this knee depend on the nucleosynthetic sources of the α-elements (O, Mg, Si, S, and Ca) and their evolution relative to [Fe/H] enrichment, providing us with information on the fundamental properties of a galaxy, such as its initial mass and its star formation timescales and intensities. In this work, we compare α-element abundances in 6 disrupted dwarf galaxies, obtained using high-resolution spectra from the Southern Stellar Stream Spectroscopic Survey (S5), to literature values for surviving (i.e., undisrupted) dSph galaxies. Our findings show significant enhancements in α-elements in stars from stellar streams compared to those found in intact dwarfs. These differences in alpha abundances – indicative of different star formation history – point to differences in the initial properties of these two categories of dwarfs, and/or the impact of environmental factors on their evolution. We discuss and evaluate a number of possible scenarios which could be responsible for the observed distinct abundance patterns.
