We present adaptive optics ( AO ) assisted integral-field spectroscopy of the intermediate-age star cluster NGC 419 in the Small Magellanic Cloud .
By investigating the cluster dynamics and the rotation properties of main sequence turn-off stars ( MSTO ) , we demonstrate the power of AO-fed MUSE observations for this class of objects .
Based on 1 049 radial velocity measurements , we determine a dynamical cluster mass of 1.4 \pm 0.2 \times 10 ^ { 5 } { M _ { \odot } } and a dynamical mass-to-light ratio of 0.67 \pm 0.08 , marginally higher than simple stellar population predictions for a Kroupa initial mass function .
A stacking analysis of spectra at both sides of the extended MSTO reveals significant rotational broadening .
Our analysis further provides tentative evidence that red MSTO stars rotate faster than their blue counterparts .
We find average V \sin i values of 87 \pm 16 { km s ^ { -1 } } and 130 \pm 22 { km s ^ { -1 } } for blue and red MSTO stars , respectively .
Potential systematic effects due to the low spectral resolution of MUSE can reach 30 { km s ^ { -1 } } but the difference in V \sin i between the populations is unlikely to be affected .