Assigned ID: 298 ----- Submission 1 (Fri Jan 21 19:02:12 GMT 2005) ----- We propose to use the data from the ACS/WFC 10452 imaging survey of M51 to study in detail the structure, dynamics, stellar populations and ongoing star formation in this unique galaxy. We intend to (1) Investigate the morphology, ionization structure, and internal reddening of an unbiased sample of HII regions in a range of galactic environments; (2) Study the relationship between HII region structure and ground-based integrated line ratios and fluxes; (3) Compare HII region structure within M51 with regions in diverse environments; (4) Investigate systematic changes in HII region structure as a function of position within the galaxy (specifically inner disk vs. outer disk and arm vs. interarm); and (5) Examine the relationship between HII region structure and the characteristics (determined from ground based data) of the ubiquitous warm ionized phase of the ISM. Using the broadband filters we will 1. Observe colors and magnitudes of individual sources within HII regions covering a range in luminosity and galactocentric radius within M51, 2. Using UV photometry of HII regions (from GALEX) as a means to improve constraints on bolometric luminosities and thus the scales of the star-forming events, 3. Comparison of the census of the stellar contents of HII regions with Halpha luminosities will be used to probe the evolutionary phase of the HII regions, 4. The stellar data will be used to study of the relationship of the stellar content of both normal and supergiant HII regions with HII region morphology, ionization structure, and integral properties, 5. Measuring recent star-forming histories in the areas surrounding HII regions, 6. The photometric data will give us information on luminosity functions within and surrounding HII regions. We intend to map in detail the star forming environments (HII regions) in the inner and outer disk to assess the impact of the galactic interaction on the global star formation process as well as how material is being channeled in and out of star forming regions. We will directly compare the structural and evolutionary properties of the star forming complexes with the apparent extinction from both FUV and FIR (Spitzer) datasets to resolve the inconsistency in the measurement of the current star formation rates from the 2 bands, and use the high resolution images to establish the real physical distribution of dust in the galactic disk. We intend to use the underlying stellar populations as well as the observed structure and distribution of current and ongoing star formation to characterize the relationship between FIR (24micron) and optical tracers of star formation. In addition we will use the HII region sample to gauge the local SF history as a function of position and determine the role of environment and triggers on the rate and efficiency of the process.

STAR FORMATION 12 49000 Support for postdoc, publication, travel false 0.0 false false false false false SUPPORTED