ASTRA Proc., 1, 23-27, 2014
https://doi.org/10.5194/ap-1-23-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
27 Jun 2014
Cosmic rays as regulators of molecular cloud properties
M. Padovani1,2,*, P. Hennebelle3, and D. Galli2 1Laboratoire de Radioastronomie Millimétrique, UMR 8112 du CNRS, École Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, 75231 Paris cedex 05, France
2INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
3CEA, IRFU, SAp, Centre de Saclay, 91191 Gif-Sur-Yvette, France
*now at: Laboratoire Univers et Particules de Montpellier, UMR 5299 du CNRS, Université de Montpellier 2, place E. Bataillon, cc072, 34095 Montpellier, France
Abstract. Cosmic rays are the main agents in controlling the chemical evolution and setting the ambipolar diffusion time of a molecular cloud. We summarise the processes causing the energy degradation of cosmic rays due to their interaction with molecular hydrogen, focusing on the magnetic effects that influence their propagation. Making use of magnetic field configurations generated by numerical simulations, we show that the increase of the field line density in the collapse region results in a reduction of the cosmic-ray ionisation rate. As a consequence the ionisation fraction decreases, facilitating the decoupling between the gas and the magnetic field.

Citation: Padovani, M., Hennebelle, P., and Galli, D.: Cosmic rays as regulators of molecular cloud properties, ASTRA Proc., 1, 23-27, https://doi.org/10.5194/ap-1-23-2014, 2014.
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