The relationship between proton temperature and momentum flux density in the solar wind

The relationship between proton temperature and momentum flux density/unit mass at 1 AU is examined using Helios 1 solar wind data from 1974 to 1980. In high-speed plasma (V greater than 500 km/s) T(p) increases with increasing n(0) V-squared, where n(0) and T(p) are the density and proton temperature at 1 AU and V is the flow speed. In lowspeed plasma (V less than 500 km/s), T(p) does not increase with increasing n(0) V-squared, and perhaps tends to decrease slightly. These basic relationships between T(p) and n(0) V-squared are not significantly affected by stream interactions. A qualitative explanation of these results is offered in the context of a solar wind model that includes deposition of momentum and energy extending well outward into the interplanetary medium.