Journal Article

Stochastic grain heating and mid-infrared emission in protostellar cores

Ya. N. Pavlyuchenkov, D. S. Wiebe, V. V. Akimkin, M. S. Khramtsova and Th. Henning

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 421, issue 3, pages 2430-2441
Published in print April 2012 | ISSN: 0035-8711
Published online April 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20480.x
Stochastic grain heating and mid-infrared emission in protostellar cores

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Stochastic heating of small grains is often mentioned as a primary cause of large infrared (IR) fluxes from star-forming galaxies, for example, at 24 m. If the mechanism does work at a galaxy-wide scale, it should show up at smaller scales as well. We calculate temperature probability density distributions within a model protostellar core for four dust components: large silicate and graphite grains, small graphite grains, and polycyclic aromatic hydrocarbon particles. The corresponding spectral energy distributions are calculated and compared with observations of a representative IR dark cloud core. We show that stochastic heating, induced by the standard interstellar radiation field, cannot explain high mid-IR emission towards the centre of the core. In order to reproduce the observed emission from the core projected centre, in particular, at 24 m, we need to increase the ambient radiation field by a factor of about 70. However, the model with enhanced radiation field predicts even higher intensities at the core periphery, giving it a ring-like appearance, which is not observed. We discuss possible implications of this finding and also discuss the role of other non-radiative dust heating processes.

Keywords: radiative transfer; stars: formation; infrared: ISM

Journal Article.  8087 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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