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G. Helou (SSC, Caltech), NGC300 ERO Team
The Spitzer Space Telescope was used to study the mid-infrared to far-infrared properties of NGC300, and to compare dust emission to H-alpha and HI to elucidate the heating of the ISM and the star formation cycle at scales <100 pc.
The new data allow us to discern HII regions as outlined by H-alpha, establish their association with the 24 micron emission, and distinguish the surrounding PDR emitting most intensely at 8 micron in the Aromatic Features. We confirm the existence and amplitude of ISM-derived dust emission at 4.6 micron, weakly detected earlier in ISO data (Lu et al. 2003), and tentatively conclude it arises in PDRs rather than HII regions. When averaging over regions larger than ~1 kpc, the ratio of H-alpha to Aromatic Feature emission in NGC300 is consistent with the disk values observed in other galaxies (Roussel et al. 2000). This offers us a more robust star formation rate indicator than H-alpha. We also discuss the mid-to-far-infrared spectral energy distribution of NGC300 in terms of pre-Spitzer models (e.g. Dale & Helou 2002).
The Spitzer Space Telescope is operated by JPL, Caltech under contract with NASA.
The author(s) of this abstract have provided an email address for comments about the abstract: helou@ipac.caltech.edu
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Bulletin of the American Astronomical Society, 36 #2
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