Bibcode
Milone, Antonino
Referencia bibliográfica
HST Proposal ID #12219. Cycle 18
Fecha de publicación:
7
2009
Número de citas
0
Número de citas referidas
0
Descripción
The recent discovery of multiple stellar populations in massive Galactic
globular clusters poses a serious challenge for models of star cluster
formation and evolution. An unique angle on this problem is being
provided by intermediate-age clusters in the Magellanic Clouds with
peculiar main-sequence turn-off morphologies. These clusters are young
enough to allow us to measure age differences of the order of 100 Myr,
as the expected age for the different stellar generations according to
the most popular theories of their origin. Recent discoveries, based on
ACS data of unparalleled photometric accuracy, have demonstrated that
the CMDs of a large fraction of these clusters { 70%} are not consistent
with the simple, single stellar population hypothesis.The conditions
under which massive Galactic globular clusters experience the formation
of multiple generations remain controversial, and even more so within
intermediate-age star clusters. To properly constraint the
multi-population phenomenon in Magellanic Cloud star clusters, we
propose deep UV/IR imaging of NGC 1846, a star cluster where multiple
populations are already identified.The proposed observation will allow
us to accurately measure the age difference between the stellar
populations providing fundamental clues on the formation mechanism, and
discover possible main sequence splitting due to different He contents.
Our simulations of WFC3 performance suggest that we will be able to
detect main sequence splitting caused by He differences as small as
DeltaY=0.02.;