  Recent discoveries of bimodal main sequences (MSs) associated with young
clusters (with ages $\lesssim 1$ Gyr) in the Magellanic Clouds have drawn a lot
of attention. One of the prevailing formation scenarios attributes these split
MSs to a bimodal distribution in stellar rotation rates, with most stars
belonging to a rapidly rotating population. In this scenario, only a small
fraction of stars populating a secondary blue sequence are slowly or
non-rotating stars. Here, we focus on the blue MS in the young cluster NGC
1850. We compare the cumulative number fraction of the observed blue-MS stars
to that of the high-mass-ratio binary systems at different radii. The
cumulative distributions of both populations exhibit a clear anti-correlation,
characterized by a highly significant Pearson coefficient of $-0.97$. Our
observations are consistent with the possibility that blue-MS stars are
low-mass-ratio binaries, and therefore their dynamical disruption is still
ongoing. High-mass-ratio binaries, on the other hand, are more centrally
concentrated.
