Upon their formation , dynamically cool ( collapsing ) star clusters will , within only a few million years , achieve stellar mass segregation for stars down to a few solar masses , simply because of gravitational two-body encounters .
Since binary systems are , on average , more massive than single stars , one would expect them to also rapidly mass segregate dynamically .
Contrary to these expectations and based on high-resolution Hubble Space Telescope observations , we show that the compact , 15–30 Myr-old Large Magellanic Cloud cluster NGC 1818 exhibits tantalizing hints at the \gtrsim 2 \sigma level of significance ( > 3 \sigma if we assume a power-law secondary-to-primary mass-ratio distribution ) of an increasing fraction of F-star binary systems ( with combined masses of 1.3– 1.6 M _ { \odot } ) with increasing distance from the cluster center , specifically between the inner 10 to 20 ^ { \prime \prime } ( approximately equivalent to the cluster ’ s core and half-mass radii ) and the outer 60 to 80 ^ { \prime \prime } .
If confirmed , this will offer support of the theoretically predicted but thus far unobserved dynamical disruption processes of the significant population of ‘ soft ’ binary systems—with relatively low binding energies compared to the kinetic energy of their stellar members—in star clusters , which we have access to here by virtue of the cluster ’ s unique combination of youth and high stellar density .