Bruno Barsella

Radiation fields inside dark clouds with variable extinction laws

The intensity of far‐ultraviolet radiation inside interstellar clouds is a crucial factor in determining their physical and chemical evolution. The intensity of UV radiation depends on the structure of the clouds, on the optical properties of interstellar grains and on the presence of embedded sources, if any. Scattering on dust grains can greatly reduce shielding effects.In the present work we compute the radiation intensity inside isolated dark clouds, making different assumptions on the structure of the clouds and on the extinction and scattering properties of dust grains. In particular, we consider the case in which extinction laws are different in different parts of the cloud.

The regulatory role of Rv in the photochemistry of dark clouds

Abstract The penetration of UV radiation inside dark clouds is discussed; and detailed calculations of Rv-dependent photorates are described. Using an accurate method for solving radiative transfer in the presence of coherent anisotropic. non-conservative scattering by dust grains, the role of the parameter Rv as the main regulatory agent of the penetration of radiation inside clouds is evidenced. Local variations in optical properties of dust and their possible link with the evolution of the cloud are also discussed.