IAU Symposium Abstract S186-073T
Bright Star Clusters in the Antennae
Analysed with Evolutionary Synthesis
U. Fritze - v. Alvensleben, O. Kurth
Universit\"atssternwarte G\"ottingen, Germany
HST WFPC1 observations revealed 738 bright star clusters spread over the
inner 12 kpc of the interacting galaxy pair NGC 4038/39. If the young
star clusters (YSCs) formed in the global starburst are (proto-) globular
or open clusters has far-reaching consequences for the formation of elliptical
galaxies. Effective radii of the YSCs are difficult to measure on WFPC1 images,
their present luminosity function (LF) looks exponential.
Evolutionary synthesis models for star clusters of various metallicities
are used to individually age-date these clusters and describe their future
luminosity and color evolution. We identify a small but plausible number of
old globular clusters (GCs). Properly accounting for age spread
effects significantly changes the shape of the YSC LF from an
exponential towards a Gaussian during further evolution.
This suggests that - at least a major part of - the YSCs may well be GCs,
implying that during a spiral-spiral merger+starburst the specific GC frequency
can increase significantly.
observed around those galactocentric radii where they formed, the YSCs serve as
tracers for the dynamical evolution of the global starburst in NGC 4038/39.
We tentatively report several radial trends in the YSCs' properties to
be verified by WFPC2 reobservations.