Mantle formation, coagulation, and the origin of cloud/core shine I. Modelling dust scattering and absorption in the infrared

作者：Jones A P^*; Koehler M; Ysard N; Dartois E; Godard M; Gavilan L

来源：Astronomy & Astrophysics, 2016, 588: A43.

DOI：10.1051/0004-6361/201527488

• dust, extinction
• ISM: general
• evolution

Context. The observed cloudshine and coreshine (C-shine) have been explained in terms of grain growth leading to enhanced scattering from clouds in the J, H, and K photometric bands and the Spitzer IRAC 3.6 and 4.5 mu m bands.
Aims. Using our global dust-modelling approach THEMIS (The Heterogeneous dust Evolution Model at the IaS), we explore the effects of dust evolution in dense clouds, through aliphatic-rich carbonaceous mantle formation and grain-grain coagulation.
Methods. We model the effects of wide band gap a-C: H mantle formation and the low-level aggregation of diffuse interstellar medium dust in the moderately-extinguished outer regions of molecular clouds.
Results. The formation of wide band gap a-C: H mantles on amorphous silicate and amorphous carbon (a-C) grains leads to a decrease in their absorption cross-sections but no change in their scattering cross-sections at near-infrared wavelengths, resulting in higher albedos.
Conclusions. The evolution of dust, with increasing density and extinction in the diffuse-to-dense molecular cloud transition, through mantle formation and grain aggregation, appears to be a likely explanation for the observed C-shine.

• 出版日期2016-4