  Observations of galactic and extra-galactic globular clusters have shown that
on average metal-rich clusters are ~3 times as likely to contain a bright X-ray
source than their metal-poor counterparts. We propose that this can be
explained by taking into account the difference in the stellar structure of
main sequence donors with masses between ~0.85 Msun and ~1.25 Msun at different
metallicities. Metal-poor main sequence stars in this mass range do not have an
outer convective zone while metal-rich stars do. The absence of this zone turns
off magnetic braking, a powerful mechanism of orbital shrinkage, leading to the
failure of dynamically formed main sequence - neutron star binaries to start
mass transfer or appear as bright low-mass X-ray binaries.
