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Session 49 - Starburst Galaxies.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center
Near-infrared spectroscopy combined with high spatial resolution imaging have been used in this work to probe the central 1 kpc region of M82. New narrowband imaging observations of the 2.36 \mum CO bandhead are combined with our previously published near-infrared hydrogen recombination-line imaging, near-infrared broadband imaging and 3.29 \mum dust feature imaging observations to study the nature of the starburst stellar population. All observations were obtained with the University of Rochester Third Generation Array Camera at the Wyoming Infrared Observatory. The recombination-line imaging was obtained with the National Air and Space Museum J/H-band Fabry-Perot and the Naval Research Lab K-band Fabry-Perot.
Our high spatial resolution recombination-line data have allowed us to obtain the most accurate extinction-corrected colors and luminosities to date toward the starburst region. Twelve different point-like sources, assumed to be stellar clusters, are identified in the extinction-corrected K-band image. A stellar population synthesis model is constructed and compared to observations. Our analysis implies that the typical burst age for these clusters is 10^7 years. In addition, our high spatial resolution observations indicate that there is an age dispersion within the starburst complex that is correlated with projected radius from the center of the galaxy. The inferred age dispersion is 6\times 10^6 years. If the starburst in M82 is propagating outwards from the center, this age dispersion corresponds to a characteristic velocity of propagation, originating in the center, of \simeq 50 km/s. Our quantitative analysis also reveals that a truncated IMF is not ! necessary to explain the integrate d properties from the central \simeq 500 pc.
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