Charging of dust particles in molecular clouds

Abstract

In molecular clouds the dust charge can be determined by non-thermal electrons from cosmic-ray ionization. If the energy of the non-thermal electrons is E≥2 keV and their fraction is only 10⁻³–10⁻⁴ of the thermal electrons in a molecular gas, the grain charge can be as high as | z | ≈ 10 in the range of gas densities n≈ 10⁵–10⁶ cm⁻³. In the high-density range n>10⁶ cm⁻³, the grain charge approaches the thermal limit | z | ≈ 0.3.

Keywords:

• Interstellar medium
• Molecular clouds
• Dust
• Charging
• Non-thermal electrons

Acknowledgements

This work was supported by the Federal Agency of Education (project code RNP 2.1.1.3483), by the Russian Foundation for Basic Research (project codes 05-02-17070 and 06-02-16819) and by the Deutsche Forschungsgemeinschaft within Sonderforschungsbereich 591 TP A6.