Mass loss in globular cluster red giants

Echelle spectra of the brightest globular-cluster red giants, taken with the 4 m telescope at Kitt Peak National Observatory, reveal the presence of emission features at Hα. These are interpreted as evidence for a circumstellar envelope, which is produced by mass loss. The gas is being lost at a velocity such that it is possible that the gas is escaping from the globular cluster. An estimate of the rate of mass loss (2 X 10^(-9) M_⊙ yr^(-1)) is obtained, which agrees well with that expected from revolutionary tracks for the difference in mass between red-giant stars and horizontal-branch stars in globular clusters.