The binary content of multiple populations in NGC 3201
  We investigate the binary content of the two stellar populations that coexist
in the globular cluster NGC 3201. Previous studies of binary stars in globular
clusters have reported higher binary fractions in their first populations (P1,
having field-like abundances) compared to their second populations (P2, having
anomalous abundances). This is interpreted as evidence for the latter forming
more centrally concentrated. In contrast to previous studies, our analysis
focuses on the cluster centre, where comparable binary fractions between the
populations are predicted because of the short relaxation times. However, we
find that even in the centre of NGC 3201, the observed binary fraction of P1 is
higher, (23.1 +/- 6.2)% compared to (8.2 +/- 3.5)% in P2. Our results are
difficult to reconcile with a scenario where the populations only differ in
their initial concentrations, but instead suggests that the populations also
formed with different fractions of binary stars.
