Abstract details

We present the re-reduced results of HST/WFPC2 photometric survey of young compact star cluster NGC1818 in Large Magellanic Cloud. The asymmetrically broadened mainsequence in CMD clearly shows the existence of binary population in this cluster. We adopt a similar mehtod to that introduced by Rubenstein & Bailyn (1997) to estimate the binary fraction of the cluster. But a much simpler strategy is used to simulate the blending effect in rich environment since their method consumes much computational time. The global binary fraction of this cluster obtained from the artificial star tests is probably in range 50%-70%.