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Inverse temperature dependence of the dust submillimeter spectral index

X. Dupac·J. -P. Bernard·N. Boudet·M. Giard·J. -M. Lamarre·C. Mény·F. Pajot·I. Ristorcelli
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Abstract

We present here a compilation of PRONAOS-based results concerning the temperature dependence of the dust submillimeter spectral index, including data from Galactic cirrus, star-forming regions and a circumstellar envelope. We observe large variations of the spectral index (from 0.8 to 2.4) in a wide range of temperatures (12 to 80 K). These spectral index variations follow a hyperbolic-shaped function of the temperature, large spectral indices (1.5-2.4) being observed in cold regions (12-20 K) while small indices (0.8-1.6) are observed in warm regions (35-80 K). Three interpretations are proposed: one is that the grain sizes change in warm and rather dense environments, another is that the chemical composition of the grains is not the same in different environments, a third one is that there is an intrinsic dependence of the dust spectral index on the temperature due to quantum processes.

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X. Dupac, J. -P. Bernard, N. Boudet, M. Giard, J. -M. Lamarre, C. Mény, F. Pajot, I. Ristorcelli. 2003-10-03. Inverse temperature dependence of the dust submillimeter spectral index. https://arxiv.org/abs/astro-ph/0310091

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