VISTA variables in Sagittarius dSph

Generally, pulsation on the Sgr dSph giant branches appears to be excited by the internal {kappa} mechanism. Pulsation amplitudes appear identical between red and asymptotic (red giant branch/asymptotic giant branch) giant stars, and between unreddened carbon and oxygen-rich stars at the same luminosity.

The lack of correlation between infrared excess and variability among oxygen-rich stars indicates that pulsations do not contribute significantly to wind driving in oxygen-rich stars in the Sgr dSph, though the low amplitudes of these stars mean this may not apply elsewhere. The dust-enshrouded carbon stars have the highest amplitudes of the stars we observe. Only in these stars does an external {kappa}-mechanism-driven pulsation seem likely, caused by variations in their more opaque carbon-rich molecules or dust.