Mid-IR forcast/SOFIA observations of M82

Abstract

We present 75″ × 75″ size maps of M82 at 6.4 μm, 6.6 μm, 7.7 μm, 31.5 μm, and 37.1 μm with a resolution of ∼4″ that we have obtained with the mid-IR camera FORCAST on SOFIA. We find strong emission from the inner 60″ (∼1 kpc) along the major axis, with the main peak 5″ west-southwest of the nucleus and a secondary peak 4″ east-northeast of the nucleus. The detailed morphology of the emission differs among the bands, which is likely due to different dust components dominating the continuum emission at short mid-IR wavelengths and long mid-IR wavelengths. We include Spitzer-IRS and Herschel/PACS 70 μm data to fit spectral energy distribution templates at both emission peaks. The best-fitting templates have extinctions of AV = 18 and AV = 9 toward the main and secondary emission peak and we estimated a color temperature of 68 K at both peaks from the 31 μm and 37 μm measurement. At the emission peaks the estimated dust masses are on the order of 104 M Ȯ. © 2012. The American Astronomical Society. All rights reserved.