9315136 Peterson In various globular clusters, stars are distributed along the horizontal branch in quite different ways. Although mass loss on the red giant branch is widely thought to be responsible for this distribution, the underlying parameter which controls the mass loss has not been established. The PI will measure rotation velocities, oxygen abundances and helium abundances for horizontal branch stars in clusters with a range of properties. This will help to establish whether any of these parameters play an important role in horizontal branch evolution. ***
