Radio observations of massive stars in the Galactic centre: The
  Quintuplet cluster
  We present high-angular-resolution radio continuum observations of the
Quintuplet cluster, one of the most emblematic massive clusters in the Galactic
centre. Data were acquired in two epochs and at 6 and 10 GHz with the Karl J.
Jansky Very Large Array. With this work, we have quadrupled the number of known
radio stars in the cluster. Nineteen of them have spectral indices consistent
with thermal emission from ionised stellar winds, five are consistent with
colliding wind binaries, two are ambiguous cases, and one was only detected in
a single band. Regarding variability, remarkably we find a significantly higher
fraction of variable stars in the Quintuplet cluster (approximately 30%) than
in the Arches cluster (< 15%), probably due to the older age of the Quintuplet
cluster. Our determined stellar wind mass-loss rates are in good agreement with
theoretical models. Finally, we show that the radio luminosity function can be
used as a tool to constrain the age and the mass function of a cluster.
