WFPC2 observations of massive and compact young star clusters in M31

We present color-magnitude diagrams of four blue massive and compact star c lusters in M31: G38, G44, G94, and G293. The diagrams of the four clusters reveal a well-populated upper main sequence and various numbers of supergia nts. The U-B and B-V colors of the upper main sequence stars are used to de termine reddening estimates of the different lines of sight in the M31 disk . Reddening values range from EB-V = 0.20 +/- 0.10 to 0.31 +/- 0.11. We sta tistically remove field stars on the basis of completeness, magnitude, and color. Isochrone fits to the field-subtracted, reddening-corrected diagrams yield age estimates ranging from 63 +/- 15 to 160 +/- 60 Myr. Implications for the recent evolution of the disk near NGC 206 are discussed.