THE INTRINSIC PROPERTIES OF THE STELLAR CLUSTERS IN THE M82 STARBURST COMPLEX: PROPAGATING STAR FORMATION?

摘要

Near-Infrared spectroscopy combined with high spatial resolution imaging have been used in this work to probe the central 500 pc of M82. Imaging observations in the 2.36 μm CO band head are added to our previously published near-infrared hydrogen recombination line imaging, near-infrared broadband imaging, and 3.29 μm dust feature imaging observations, in order to study the nature of the starburst stellar population. A starburst model is constructed and compared with the observations of the stellar clusters in the starburst complex. Our analysis implies that the typical age for the starburst clusters is 10~7 yr. In addition, our high spatial resolution observations indicate that there is an age dispersion within the starburst complex that is correlated with projected distance from the center of the galaxy. The inferred age dispersion is 6 x 10~6 yr. If the starburst in M82 is propagating outward from the center, this age dispersion corresponds to a velocity of propagation, originating in the center, of ～50 km s~(-1). Our quantitative analysis also reveals that a Salpeter initial mass function, extending from 0.1 to 100 solar mass, can fit the observed properties of M82 without using up more than 30% of the total dynamical mass in the starburst.