Binary stars are predicted to have an important role in the evolution of globular clusters , so we obtained binary fractions for 35 globular clusters that were imaged in the F606W and F814W with the ACS on the Hubble Space Telescope .
When compared to the values of prior efforts ( 29 ; 22 ) , we find significant discrepancies , despite each group correcting for contamination effects and having performed the appropriate reliability tests .
The most reliable binary fractions are obtained when restricting the binary fraction to q \geq 0.5 .
Our analysis indicates that the range of the binary fractions is nearly an order of magnitude for the lowest dynamical ages , suggesting that there is a broad distribution in the binary fraction at globular cluster formation .
Dynamical effects also appears to decrease the core binary fractions by a factor of two over a Hubble time , but this is a weak relationship .
We confirm a correlation from previous work that the binary fraction within the core radius decreases with cluster age , indicating that younger clusters formed with higher binary fractions .
The strong radial gradient in the binary fraction with cluster radius appears to be a consequence of dynamical interactions .
It is often not present in dynamically young clusters but nearly always present in dynamically old clusters .