S316p.49 — Fundamental Parameters of a Large, Unbiased Sample of Massive, Young, Embedded Star Clusters in the Milky Way

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Yigit Dallilar2, Peter Barnes2, Elizabeth Lada2, Stuart Ryder1

Institution(s): 1. Australian Astronomical Observatory, 2. University of Florida

Massive star cluster formation in our Galaxy is still a mystery. Unlike studies on nearby star formation regions (Pleiades, Orion Nebula), there is no unbiased sample of massive young star clusters except the CHaMP survey, which is focused on the Carina Arm (Barnes et al. 2011, ApJS, 196, 12). In this project, we examine properties of young clusters identified in the CHaMP survey through infrared photometry. Near infrared (J,H,K) imaging was obtained with the Australian Astronomical Telescope and deep mid infrared (IRAC bands 1,2) imaging was obtained with the Spitzer Space Telescope during the warm mission. Photometric analysis was performed with a combination of Sextrac- tor and Psfex software. Photometric calibration for NIR data was handled exploiting 2Mass coverage for our fields. For MIR data, photometric calibration was obtained using GLIMPSE coverage for a small number of our images, then bootstrapping this to calibrate other images, since all images are obtained with the same pipeline. To identify cluster members, we provide constraints on the source classification using field AGB stars and faint background galaxies, which have similar characteristics as reddened young stellar objects. Predicted locations of these objects on color-magnitude and color-color diagrams are used as a guide, as are the stellar classification parameter from Sextractor and faint galaxy catalogs covering our fields. We also examine extinction properties towards these young clusters, exploiting well known properties of AGB star population in our fields. Combining the IR data with existing mm-wave specroscopy, we compute values for the gas to dust ratio of these young clusters using extinction properties plus differential H-K color maps and NH column density measurements, all obtained as a part of the CHaMP survey. These results help us to identify evolutionary stages of these young clusters. Eventually, we will constrain cluster properties like age, distance and metallicity with isochrone fitting routines.