Dust extinction and the initial mass function in the starburst galaxy M82

The apparently low extinction toward the nucleus of M82 inferred from optical and near-IR recombination line and continuum studies |(AV~ 5 \,mag)| may be reconciled with the much larger values inferred from mid-IR and longer wavelength measurements |(AV~ 25 \,mag)| if the dust and radiating sources are well mixed along the line-of-sight. Existing near-IR data, which potentially could delineate the three-dimensional dust distribution, are of insufficient accuracy. If the large extinction derived from long-wavelength data attenuates the emission from giant and supergiant stars, then the initial mass function in M82 may be deficient in low-mass stars.