2008ApJ...678..950S

The momentum transfer and viscosity cross sections for proton-hydrogen collisions are computed in the velocity range of ∼200-20,000 km/s relevant to a wide range of astrophysical environments such as supernova remnant shocks, solar wind, winds within young stellar objects or accretion disks, and interstellar protons interacting with the heliosphere. A variety of theoretical approaches are used to arrive at a best estimate of these cross sections in this velocity range that smoothly connect with very accurate results previously computed for lower velocities. Contributions to the momentum transfer and viscosity cross sections from both elastic scattering and charge transfer are included.