The formation of molecular hydrogen in the interstellar medium takes place on the surfaces of dust grains. Hydrogen molecules play a role in gasphase reactions that produce other molecules, some of which serve as coolants during gravitational collapse and star formation. Thus, the evaluation of the production rate of hydrogen molecules and its dependence on the physical conditions in the cloud ...

Over the last decades, remote observation tools and models have been developed to improve forecasting of ash-rich volcanic plumes. One challenge in these forecasts is knowing properties at vent, including mass eruption rate grain size distribution (GSD). Volcanic lightning a common feature explosive eruptions with high rates fine particles. The GSD expected play major role generating gas thrust...