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Chemistry and kinematics of stars in Local Group galaxies

(2007) Battaglia, Giuseppina

This thesis is entitled "Chemistry and kinematics of stars
in Local Group galaxies" and its main goal is to use
dwarf spheroidal galaxies (dSphs), the smallest galaxies known,
as probes of galaxy formation and evolution theories. These galaxies are of particular interest
because they appear to contain enormous amounts of dark matter. Also
dSphs are very old and may carry
information about early star formation in the Universe.
Because of their relative simplicity they
offer a great opportunity to learn about galaxy formation and evolution processes
and how they affect star formation and chemical enrichment.

In this thesis I study the properties of the resolved stellar populations
of the Sculptor and Fornax
dSphs, which are satellites of the Milky Way. For this I have used large wide field photometric and
spectroscopic datasets from ESO/WFI and VLT/FLAMES.

I found spatial variations of the star formation and chemical enrichment histories in these galaxies:
old and metal poor stars are distributed throughout these
galaxies, whilst younger and more metal rich stars formed preferentially in the central regions.
This suggests that the gas was removed from the
outer regions by supernovae explosions and/or
tidal or ram pressure stripping caused by interaction with the Milky Way.

I found that Scl is about 10 times more massive than previously thought
and contains about 160 times more dark than luminous matter.