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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 24\mu m. If the mechanism does work at a galaxy-wide scale, it should show up at smaller scales as…

Astrophysics of Galaxies · Physics 2015-06-03 Ya. N. Pavlyuchenkov , D. S. Wiebe , V. V. Akimkin , M. S. Khramtsova , Th. Henning

We investigated the effect of time-dependent ice growth on dust grains on the opacity and hence on the dust temperature in a collapsing molecular cloud core, with the aim of quantifying the effect of the dust temperature variations on ice…

Astrophysics of Galaxies · Physics 2024-10-16 O. Sipilä , P. Caselli , M. Juvela

Interstellar dust spans a wide range in size distribution, ranging from ultrasmall grains of a few Angstroms to micrometer-size grains. While the presence of nanometer-size dust grains in the Galactic interstellar medium was speculated six…

Astrophysics of Galaxies · Physics 2018-11-14 Yanxia Xie , Luis C. Ho , Aigen Li , Jinyi Shangguan

An accurate knowledge of the mineralogy (chemical composition and crystal structure) of the silicate dust in the interstellar medium (ISM) is crucial for understanding its origin in evolved stars, the physical and chemical processing in the…

Astrophysics · Physics 2009-11-13 M. P. Li , G. Zhao , Aigen Li

High resolution X-ray imaging offers a unique opportunity to probe the nature of dust in the z ~< 2 universe. Dust grains 0.1- 1 um in size will scatter soft X-rays, producing a diffuse "halo" image around an X-ray point source, with a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Lia Corrales , Frits Paerels

We present a catalogue of molecular cloud cores drawn from high latitude, medium opacity clouds, using the all-sky IRAS Sky Survey Atlas (ISSA) images at 60 and 100~$\mu$m. The typical column densities of the cores are $ N(H_2)\sim 3.8…

Astrophysics · Physics 2009-10-31 N. E. Jessop , D. Ward-Thompson

We present a model for the diffuse interstellar dust that explains the observed wavelength-dependence of extinction, emission, linear and circular polarisation of light. The model is set-up with a small number of parameters. It consists of…

Astrophysics of Galaxies · Physics 2015-06-16 R. Siebenmorgen , N. V. Voshchinnikov , S. Bagnulo

Theoretical arguments suggest that dust grains should grow in the dense cold parts of molecular clouds. Evidence of larger grains has so far been gathered in near/mid infrared extinction and millimeter observations. Interpreting the data…

Astrophysics of Galaxies · Physics 2015-05-14 J. Steinacker , L. Pagani , A. Bacmann , S. Guieu

We present a new method to constrain the grain size in protoplanetary disks with polarization observations at millimeter wavelengths. If dust grains are grown to the size comparable to the wavelengths, the dust grains are expected to have a…

In many models of dusty objects in space the grains are assumed to be composite or fluffy. However, the computation of the optical properties of such particles is still a very difficult problem. We analyze how the increase of grain porosity…

Astrophysics · Physics 2009-11-11 N. V. Voshchinnikov , V. B. Il'in , Th. Henning , D. N. Dubkova

A photon of wavelength lambda ~1 micron interacting with a dust grain of radius a_p ~ 1 mm (a "pebble") undergoes scattering in the forward direction, largely within a small characteristic diffraction angle theta_s ~ lambda/a_p ~ 100".…

Astrophysics · Physics 2009-08-24 Aristotle Socrates , Bruce T. Draine

We have constructed three-dimensional models for the equilibrium abundance of molecular hydrogen within diffuse interstellar clouds of arbitrary geometry that are illuminated by ultraviolet radiation. The position-dependent photo-…

Astrophysics · Physics 2009-10-30 Marco Spaans , David A. Neufeld

Using the APEX-12m telescope, continuum maps at 350~$\mu$m of eight gas-dust clouds from the southern hemisphere are obtained. Clouds are associated with the regions of massive star and star cluster formation and have dense cores. Core…

Astrophysics of Galaxies · Physics 2023-01-12 L. E. Pirogov

Infrared photometry and spectroscopy (1-25 um) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of the grains and the composition of the ices before they are incorporated into…

We present mid-IR imaging observations of a high Galactic latitude cirrus obtained with the ISO camera ISOCAM at 6" angular resolution. The observations were done with two filters LW2 (5-8.5 microns) and LW3 (12-18 microns) that measure…

Astrophysics · Physics 2009-11-07 M. -A. Miville-Deschenes , F. Boulanger , G. Joncas , E. Falgarone

A detailed study of interstellar polarization efficiency toward molecular clouds is used to attempt discrimination between grain alignment mechanisms in dense regions of the ISM. Background field stars are used to probe polarization…

Astrophysics · Physics 2008-11-26 D. C. B. Whittet , J. H. Hough , A. Lazarian , Thiem Hoang

The size of dust grains, $a$, is key to the physical and chemical processes in circumstellar disks, but observational constraints of grain size remain challenging. (Sub)millimeter continuum observations often show a percent-level…

The extinction curve of interstellar dust in the dense molecular cloud cores is crucial for understanding dust properties, particularly size distribution and composition. We investigate the infrared extinction law in four nearby isolated…

Astrophysics of Galaxies · Physics 2024-11-04 Jun Li , Bingqiu Chen , Biwei Jiang , He Zhao , Botao Jiang , Xi Chen

Observations of H3+ in the Galactic diffuse interstellar medium (ISM) have led to various surprising results, including the conclusion that the cosmic-ray ionization rate (zeta_2) is about 1 order of magnitude larger than previously…

Astrophysics of Galaxies · Physics 2015-06-03 Nick Indriolo , Benjamin J. McCall

For 117 clusters of galaxies, we explore the detectability of intracluster dust grains by current and future infrared facilities, taking into account both collisional heating and sputtering of grains by ambient plasma. If the dust grains…

Astrophysics · Physics 2015-06-24 Kenkichi Yamada , Tetsu Kitayama