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Paper: Aromatic Features in M101 HII Regions and Starburst Galaxies
Volume: 381, The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution
Page: 122
Authors: Gordon, K.D.; Engelbracht, C.; Smith, J.D.T.; Rieke, G.; Misselt, K.
Abstract: The behavior of the aromatic features as a function of metallicity/radiation field hardness in M101 HII regions and starburst galaxies is investigated using Spitzer/IRS spectra. These spectra reveal that the 6.2, 7.8+8.6, and 11.3 μm aromatics have different dependencies on metallicity/radiation field hardness. Specifically, the 6.2 and 7.8+8.6 μm aromatics are weak or absent at a metallicity, 12+log(O/H), of ∼8.0 while the 11.3 μm feature remains relatively strong. These results apply to both the M101 HII regions and starbursts showing that HII regions can indeed be thought of as “mini-starbursts.” Comparison of this work with various candidate materials results in a good match with the annealing behavior in Quenched Carbonaceous Composite (QCC) which is an amorphous, hydrogenated, carbonaceous solid.
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