The Anatomy of Star Formation in NGC 300

Abstract

The Spitzer Space Telescope was used to study the mid-infrared to\nfar-infrared properties of NGC 300, and to compare dust emission to Halpha to\nelucidate the heating of the ISM and the star formation cycle at scales < 100\npc. The new data allow us to discern clear differences in the spatial\ndistribution of 8 micron dust emission with respect to 24 micron dust and to\nHII regions traced by the Halpha light. The 8 micron emission highlights the\nrims of HII regions, and the 24 micron emission is more strongly peaked in star\nforming regions than at 8 microns. We confirm the existence and approximate\namplitude of interstellar dust emission at 4.5 microns, detected statistically\nin Infrared Space Observatory (ISO) data, and conclude it arises in star\nforming regions. When averaging over regions larger than ~ 1 kpc, the ratio of\nHalpha to Aromatic Feature emission in NGC 300 is consistent with the values\nobserved in disks of spiral galaxies. The mid-to-far-infrared spectral energy\ndistribution of dust emission is generally consistent with pre-Spitzer models.\n