| Abstract : | Dwarf galaxies provide a laboratory for studying the chemical evolution in systems with different galaxy parameters than our Milky Way, such as less-efficient star formation histories and IMFs that are deficient in the most massive stars. Studying these can help pinpoint which nucleosynthetic processes are either more or less prominent in smaller galaxies. The Sagittarius dwarf galaxy is our closest satellite dwarf galaxy, which is also currently undergoing a merger event with the Milky Way. Here, using high resolution ($R \gtrsim 45,000$), high signal-to-noise ($\sim 90-100$ per-pixel) stellar spectra, we present our results on the chemical abundances of two relatively metal-rich stars in the core of Sagittarius dSph. We measured a total of 14 different species, including the alpha-process, iron-peak, odd-Z (e.g. Na, Al), and heavy neutron capture elements (La, Ba and Eu). Our estimates are consistent with past studies of Sgr, including those of the APOGEE Survey (Hasselquist et al. 2017). We reconfirm a deficiency in the alpha-element trends relative to the Milky Way, supporting the scenario that the IMF of Sgr might have had a paucity of the most massive stars. Speaking of neutron-capture processes, the s-process appears to have a significantly higher contribution in Sgr than in the Milky Way disk. Also, we note that the consistent sub-solar [Ni/Fe] we’ve measured, with a declining slope consistent with the APOGEE Survey results, could be explained by the putative sub-Chandrasekhar mass type Ia supernovae contributing to the chemical evolution of Sagittarius. In the future, given the high quality of our spectra and the spatial coverage of our remaining sample, we will search for systematic differences that imply chemical inhomogeneities and radial abundance gradients in Sagittarius. |
