(H-W2)-W1 vs W2-(BP-K) for 4 open cluster members

In particular, here we estimate the binary and multiple star ratios and the distribution of the component mass ratio q in the Galactic clusters AlphaPersei, Praesepe, and NGC1039. We have modified the procedure outlined in our first study making star counts automatic and by introducing bootstrapping for error estimation.

Basing on this, we reinvestigated the Pleiades star cluster in the same mass range as in our previous work and corrected an inaccuracy in the mass ratio q distribution. The binary and multiple star ratio in the four clusters is then found to lie between 0.45{+/-}0.03 and 0.73{+/-}0.03. On the other hand, the ratio of systems with multiplicity more than 2 is between 0.06{+/-}0.01 and 0.09{+/-}0.02.