AAS 198th Meeting, June 2001
Session 42. Star Clusters
Display, Tuesday, June 5, 2001, 10:00am-6:30pm, Exhibit Hall

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[42.08] The Low End of the Initial Mass Function in the Young LMC Cluster NGC 2164

M. Sirianni (Johns Hopkins University), A. Nota (STScI/ESA), G. De Marchi (STScI/ESA), C. Leitherer (STScI), M. Clampin (STScI)

We present a new study of the low end of the stellar IMF of NGC 2164, a rich young star cluster in the Large Magellanic Cloud (LMC). We obtained deep broadband V and I HST/WFPC2 images which have allowed us to detect stars down to a limiting magnitude of F555W = 25.3. At the distance of the LMC, this correspond to stellar masses of ~ 0.6 Mo.

NGC 2164 is one of four clusters (with NGC 2156, NGC 2159 and NGC 2172) which are likely to have formed in a single HI complex (Elson et al. 1987) in a coeval episode of star formation. They extend over a region of 375 pc x 270 pc in size and very plausibly have similar metallicity. However, they have very different core radii (5.7 to 9.1 arcsec)and therefore different stellar densities. We derived the cluster luminosity function for NGC 2164, which is the richest member of the quartet. We constructed its initial mass function in the 1-7 Mo range as a function of the distance from the cluster center. We compare the main features in the CMD, LM and IMF of NGC 2164 with previously investigated clusters in our sample, with different age, metallicity and star density.

This study is part of a larger program aimed to investigate the universality of the IMF at low masses in eleven young clusters in the LMC/SMC - at different conditions of stellar density, age and metallicity - to understand whether, at small masses, the IMF is constrained by local conditions. In order to minimize the uncertainties associated with data reduction and interpretation, the data for each cluster have been gathered according to a specific strategy and have been treated with a homogeneous data reduction and analysis procedure and a unique choice of models.

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