Abundances in 16 red-giant in NGC 7789

We focus on the light element group CNOLi that provides clues to evolutionary changes associated with internal fusion events and chemical mixing. We confirm and extend an early report that NGC7789 stars 193 and 301 have anomalously large Li abundances, and that these values are apparently unconnected to any other elements' abundances in these stars.

A companion study of HeI{lambda}10830 lines in both field stars and cluster members shows that star 301 has a strong He feature while star 193 does not. Possible explanations for the large Li abundances of these stars include helium flash-induced mixing events and binary interactions at some past or present times. In either case an internal eruption of energy could cause fresh synthesis of lithium via the Cameron-Fowler Berillyum transport mechanism.