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Session 61 - New Views of the Magellanic Clouds.
Display session, Wednesday, June 12
Great Hall,

[61.02] The Anon(R\,132) Cluster in 30\,Dor -- the Poor Older Sibling of R\,136

E. K. Grebel, Y. -H. Chu, D. J. Bomans, S. D. Points (U. Illinois)

At a distance of 50 kpc, 30\,Doradus provides a unique opportunity to study the detailed star formation history in a giant starburst region. 30\,Dor contains two clusters: the famous, compact, young R\,136 cluster at its core, and an anonymous, poorer, older cluster \approx 3' to the northwest. We call this anonymous cluster Anon(R\,132), since R\,132 is only 20'' from the cluster center. While the R\,136 cluster has been the focus of numerous studies, the Anon(R132) cluster has been neglected. Thus, our understanding of the starburst in 30 Dor is severely limited.

We have obtained HST WFPC2 images of the Anon(R\,132) cluster in the F336W, F555W, F814W, and F656N filters, roughly corresponding to the U, V, I, and H\alpha bands. The photometry reaches V \approx 24 mag and spans at least 12 mag. The color-magnitude diagrams show an extended main sequence with a small number of supergiants. Analysis of these data will allow us to examine the stellar content and derive the age of Anon(R\,132). The H\alpha and continuum images allow us to identify Be candidates and potential pre-main sequence stars. We will examine the slope and low-mass end of the initial mass function (IMF) of Anon(R\,132), and compare it with R\,136. Furthermore, we will use the derived IMF to estimate the stellar wind and supernova energy input into the ambient interstellar medium. This study will significantly enhance our understanding of cluster formation in starbursts.

Program listing for Wednesday