Abstract
The discovery of multiple evolutionary sequences has challenged the paradigm
that globular clusters (GCs) host simple stellar populations. In addition,
spectroscopic studies of GCs show a spread in light-element abundances,
suggesting that multiple sequences can be formed from gaseous ejecta processed
in evolved cluster stars. If multiple sequences originate from within GCs, then
it should be determined how such stellar systems retain gas, form new stars
within them and subsequently evolve. Here we expand upon previous studies and
carry out hydrodynamical simulations that explore a wide range of cluster
masses, compactness, metallicities and stellar age combinations in order to
determine the ideal conditions for gas retention. We find that up to 6.4% of
the mass of the star cluster can be made up of retained stellar wind gas at the
time star formation is triggered. However, we show that multiple episodes of
star formation can take place during the lifetime of a star cluster in
particular for times $1$ Gyr, thus leading to a sizable enhancement in
the total number of new stars. The fact that this favorable star formation time
interval coincides with the asymptotic giant branch (AGB) phase seems to give
further credence to the idea that, at least in some GCs, there are stars which
have formed from material processed by a previous generation of stars. The
ability of extended heating sources, such as pulsar outflows or accretion onto
compact objects, to hamper gas retention is illustrated via a simple numerical
treatment.
Users
Please
log in to take part in the discussion (add own reviews or comments).