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Astron. Astrophys. 349, L25-L28 (1999)

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Letter to the Editor

The temperature of non-spherical interstellar grains

N.V. Voshchinnikov 1, D.A. Semenov 1 and Th. Henning 2

1 Sobolev Astronomical Institute, St. Petersburg University, Bibliotechnaya pl. 2, 198904 St. Petersburg-Peterhof, Russia
2 Astrophysical Institute and University Observatory, Friedrich Schiller University, Schillergässchen 3, D-07745 Jena, Germany

Received 5 July 1999 / Accepted 11 August 1999


A model of spheroidal particles is used to calculate the steady-state temperature of dust grains immersed in the interstellar radiation field. It is found that the temperature of non-spherical grains with the aspect ratios [FORMULA] deviates from that of spheres less than 10 %. More elongated or flattened particles are usually cooler than spheres of the same mass and in some cases the temperatures may differ by even about a factor of 2. The shape effects increase with the infrared absorptivity of the grain material and seem to be more important in dark interstellar clouds.

Key words: radiation mechanisms: thermal – ISM: dust, extinction – infrared: ISM: continuum

Send offprint requests to: N.V. Voshchinnikov (nvv@aispbu.spb.su)

© European Southern Observatory (ESO) 1999

Online publication: August 25, 1999