Lithium Abundances in delta Scuti Stars and Their Relationship with the Lithium Dip

Several years ago it was suggested that mass loss from δ Scuti stars may transform them into the lithium "dip,, stars seen in open clusters like Coma Berenices and the Hyades. Although there is evidence to indicate that this is unlikely, there has never been a study made of the lithium abundances in δ Scuti stars themselves. This paper reports the results of a survey of lithium in these stars. Lithium was detected in about half of the stars studied, with only upper limits being determined for the others. For those stars with measurable lithium there is evidence for a moderate depletion at the cooler temperatures. For those stars with no measurable lithium, the upper limits are consistent with only moderate depletion in all except one or two cases. There is no correlation between lithium depletion and a star's rotational velocity, mass, gravity, period of pulsation, or metallicity. There is, therefore, no support for the suggestion that mass loss on the main sequence due to δ Scuti pulsation may be responsible for the lithium dip stars. However, the data cannot exclude the possibility that mass loss may be responsible for a degree of lithium depletion in δ Scuti stars. Interestingly, though most elements are in solar ratio to iron, there is evidence for a pronounced carbon abundance deficiency in all of the stars with measurable carbon.