David Whelan (U. Virginia)

The Early Evolution of Super Star Clusters: Predictions Using Dust and Molecular Line Radiative Transfer Models

ABSTRACT: From their discovery in the early 1970s until the present
time, super star clusters (SSCs) have been classified as the most
luminous and dense star clusters known to exist. They are now believed
to be one possible progenitor of globular clusters. As revealed using
the Hubble Space Telescope (e.g. de Marchi et al. 1997) they have
half-light radii of about 1.7pc, and masses of around 1e5 to 1e6 solar
masses have been measured using various techniques. It was not until
the turn of the century (Turner et al. 2000, Shioya et al. 2001,
Johnson et al. 2001) that the first measurements of SSCs deeply
embedded in circum-cluster material were made. Since then, the masses
and sizes have largely been confirmed for these thickly-obscured SSCs
primarily with radio free-free data. Despite the now large wealth of
data on super star clusters and their embedded counterparts, little is
known about their physical conditions. Using what available data there
is concerning size, mass densities, and stellar populations, I have
performed a large grid of dust radiative transfer models along
geometrical tracks that are meant to roughly mimic their evolution
from heavily-obscured to optically visible SSCs. The results are
presented in Whelan et al. (2011, 729, 111). In addition, and in
preparation for observations with the new Atacama Large
Millimeter/submillimeter Array (ALMA) in Chile, which will provide the
observational community with previously unavailable spatial resolution
at millimeter wavelengths, I have begun to create a grid of CO and HCN
measurements of embedded SSCs, utilizing the geometries presented in
Whelan et al. (2011). I will present an overview of my dust models as
well as the brand new and ongoing molecular lines study.