I performed photometry on ∼900,000 stars in 27 Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) fields in the disk of M31 to confirm the youth of several blue globular-like clusters in M31, to objectively discover and measure rough ages for dozens of new young open cluster candidates in the spiral arms, and to determine rough star formation and chemical evolution histories for the field stars in these portions of the disk. The ages measured for the blue globular-like clusters are consistent with the propagation of star formation through the southern half of the M31 disk, suggesting that these clusters formed as core clusters in large OB associations like NGC 206. The open cluster studies revealed a broad range in ages covering the full sensitivity of our experiment, suggesting relatively constant star formation in the spiral arm regions over the past few hundred Myr. The field star formation history measurements revealed that, similar to our own Galaxy, the disk of M31 lacks old, metal-poor stars; the histories also show a decrease in the star formation rate of the disk as a whole over the past ∼1 Gyr. I complemented this work with wide-field ground-based photometry of ∼100,000 stars covering most of the M31 disk. Analysis of these data confirmed that some arms are rich in stars with ages up to and greater than ∼100 Myr. This analysis also revealed that the star formation rate in some spiral arms has increased in the past ∼10 Myr.
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