Metals Removed by Outflows from Milky Way Dwarf Spheroidal Galaxies
  The stars in the dwarf spheroidal satellite galaxies (dSphs) of the Milky Way
are significantly more metal-poor than would be expected from a closed box
model of chemical evolution. Gas outflows likely carried away most of the
metals produced by the dSphs. Based on previous Keck/DEIMOS observations and
models, we calculate the mass in Mg, Si, Ca, and Fe expelled from each of eight
dSphs. Essentially, these masses are the differences between the observed
amount of metals present in the dSphs' stars today and the inferred amount of
metals produced by supernovae. We conclude that the dSphs lost 96% to >99% of
the metals their stars manufactured. We apply the observed mass function of
Milky Way dSphs to the ejected mass function to determine that a single large
dSph, like Fornax, lost more metals over 10 Gyr than all smaller dSphs
combined. Therefore, small galaxies like dSphs are not significant contributors
to the metal content of the intergalactic medium. Finally, we compare our
ejected mass function to previous X-ray measurements of the metal content of
the winds from the post-starburst dwarf irregular galaxy NGC 1569. Remarkably,
the most recent starburst in that galaxy falls exactly on the ejected
mass-stellar mass relation defined by the Milky Way dSphs.
