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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, e.g. at 24mu 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 infrared dark cloud core. We show that stochastic heating, induced by the standard interstellar radiation field, cannot explain high mid-IR emission toward the centre of the core. In order to reproduce the observed emission from the core projected centre, in particular, at 24mu 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, that is not observed. We discuss possible implications of this finding and also discuss a role of other non-radiative dust heating processes.
In recent years, dramatic outbursts have been identified toward massive protostars via infrared and millimeter dust continuum and molecular maser emission. The longest lived outburst ($>6$ yr) persists in NGC6334I-MM1, a deeply-embedded object with n
How and when in the star formation sequence do dust grains start to grow into pebbles is a cornerstone question to both star and planet formation. We compute the polarized radiative transfer from a model solar-type protostellar core, using the POLARI
We investigate the young (proto)stellar population in NGC 2023 and the L 1630 molecular cloud bordering the HII region IC 434, using Spitzer IRAC and MIPS archive data, JCMT SCUBA imaging and spectroscopy as well as targeted BIMA observations of one
Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having
We present high-angular (~0.4) resolution mid-infrared (MIR) polarimetric observations in the 8.7 ${mu}$m and 11.6 ${mu}$m filters of Cygnus A using CanariCam on the 10.4-m Gran Telescopio CANARIAS. A highly polarized nucleus is observed with a degre