||Resolved Stars in M83 Based on HST/WFC3 Early Release Science Observations
||440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function?
||Kim, H.; Whitmore, B. C.; Windhorst, R. A.
||We present a multi-wavelength photometric study of individual stars in
M83 based on observations taken as part of the WFC3 Early Release
Science (ERS) program. The central region of M83 has been imaged in
seven broad-band filters to obtain multi-wavelength coverage from the
near-UV to the near-IR. We use four filters–F336W, F438W, F555W, and
F814W–to measure the UBVI photometric colors and intrinsic
luminosity for ∼10,000 stars. These measurements are used to
determine the recent (< 1 Gyr) star formation history of M83. We
selected 50 regions in the spiral arm and the inter-arm area of M83
and categorize them based on their Hα morphology. To determine
ages of stars in each region, the color-magnitude diagrams (CMDs) and
the color-color diagrams were used with the Padova isochrones at a
metallicity of Z=0.03 (1.5 Z☉). We correct the foreground and
internal extinction of individual stars using the reddening-free Q
parameter and improve our age estimates of stars from the isochrone
fitting on the CMDs. Comparisons of stellar ages and cluster ages
based on both their Hα morphology and their spectral energy
distribution (SED) fitting were made and show fairly good
correlations. We also find that the regions with ages determined
younger than 10 Myr are located preferentially along the active
star-forming regions on the spiral arm.