Evan Kirby - Cal Tech

The Chemical Evolution of Milky Way Satellite Galaxies from Keck Spectroscopy

I will present a Keck/DEIMOS spectroscopic campaign of eight Milky Way dwarf spheroidal (dSph) satellite galaxies. The primary data product is a catalog of nearly 3000 stars with spectral synthesis-based abundance measurements of Fe and the alpha elements Mg, Si, Ca, and Ti. The dSph metallicity distributions show that the histories of the less luminous dSphs were marked by massive amounts of gas loss. From the [alpha/Fe] distributions, I will demonstrate that the early star formation histories of most dSphs was very similar and that Type Ia supernova ejecta contribute to the abundances of all but the most metal-poor ([Fe/H] < -2.5) stars. I will also make inferences about past outflows from the dSphs in order to determine their contribution to the metal content of the intergalactic medium.

Gurtina Besla - Columbia

The Magellanic System

I will present new simulations of our nearest example of an interacting pair of dwarf galaxies, the Magellanic Clouds. Through detailed studies of their orbital evolution and large scale structure, insights can be gleaned into processes that affect the evolution of dwarf galaxies more generally. In particular, owing to a recent direct collision with the Large Magellanic Cloud (LMC), the Smalle Magellanic Cloud appears to be an object in the midst of a transition from a Dwarf Irregular galaxy to a Dwarf Spheroidal. This same collision has left the LMC with an offcenter bar and one armed spiral structure, features characteristic of a class of dwarf galaxies known as Magellanic Irregulars. Such interactions are not only important for the evolution of dwarf galaxies but also have direct consequences for the buildup of baryons in our own Milky Way, as LMC-mass systems are believed to be the dominant building blocks of Milky Way-type halos.