Dusty magnetohydrodynamics in star-forming regions

Star formation occurs in dark molecular regions where the number density of hydrogen nuclei nH exceeds 104 cm−3 and the fractional ionization is 10−7 or less. Dust grains with sizes ranging up to tenths of microns and perhaps down to tens of nanometers contain just less than 1% of the mass. Recombination on grains is important for the removal of gas-phase ions, which are produced by cosmic rays penetrating the dark regions. Collisions of neutrals with charged grains contribute significantly to the coupling of the magnetic field to the neutral gas. Consequently, the dynamics of the grains must be included in the magnetohydrodynamic models of large-scale collapse, the evolution of waves and the structures of shocks important in star formation.

Transfer of continuum UV radiation inside fragmented clouds

The penetration of visible and UV continuum radiation is a governing factor for many processes inside interstellar clouds. It determines for instance: 1) the overall chemical equilibrium (formation/destruction of molecules and neutral or ionized species, fractional ionization of the gas which is directly related to the coupling with the magnetic field); 2) the overall energy balance (heating of the dust, heating of the gas through collisions with electrons extracted from grains by the photoelectric effect or with grains; 3) cooling of the gas due to fine structure line emission (OI,CI,CII).

Transfer of continuum UV radiation inside fragmented clouds

The penetration of visible and UV continuum radiation is a governing factor for many processes inside interstellar clouds. It determines for instance: 1) the overall chemical equilibrium (formation/destruction of molecules and neutral or ionized species, fractional ionization of the gas which is directly related to the coupling with the magnetic field); 2) the overall energy balance (heating of the dust, heating of the gas through collisions with electrons extracted from grains by the photoelectric effect or with grains; 3) cooling of the gas due to fine structure line emission (OI,CI,CII).