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The study of the star formation history (SFH) of
nearby galaxies from resolved stars is a powerful tool to shed light
on the mechanisms driving the formation and evolution of galaxies.
In particular, isolated dwarfs are ideal laboratories since their
evolution has not been complicated by the strong gravitational
influence of giant galaxies. The SFH therefore might hold clues to
the importance of processes such as reionization or supernovae
feedback on the evolution of dwarf galaxies.
On the other hand, the pulsational properties of the variable stars
provide an independent approach to constrain these physical
mechanisms, because they can trace subtle differences in the age and
metallicity of the parent populations.
In this talk I will present the LCID Project (Local Cosmology from
Isolated Dwarfs) aiming at reconstructing the full star formation
history of a sample of isolated dwarf galaxies of the Local Group,
based on very deep (V~29), multi-epoch HST/ACS data. The sample
includes representatives of the main morphological types: IC1613 and
Leo A (dIrr), LGS3 and Phoenix (transition dIrr/dSph), and Cetus and
Tucana (dSph). We will discuss the main results concerning the SFH
that have been derived through comparison with synthetic
color-magnitude diagrams, and the additional constraints on the SFH
put by the properties of the variable stars. |
