A WIYN near-infrared investigation of three massive star-forming regions

We investigate three embedded massive star-forming regions using the Near-Infrared Imager (NIRIM) camera on the 3.5 m WIYN telescope. We report J-, H-, and K'- band photometry in the clusters AFGL437, AFGL5180, and AFGL5142, and use these results to probe the stellar populations, extinction, and ages of the clusters. We find that all three clusters suffer significant extinction (A(K) similar to 1), have ages <= 5 Myr, and are actively forming stars. The background-corrected percentages of cluster members identified as young stellar objects (YSOs) in AFGL437, AFGL5180, and AFGL5142 are 58% +/- 15%, 75% +/- 10%, and 78% +/- 15%, respectively. The slopes of the K-band luminosity functions (KLFs) for these clusters are similar to 0.3-0.4, similar to that in other young clusters. Both the percentage of YSOs and KLF slopes of these clusters indicate that their ages are <5 Myr. We investigate the consequences of incompleteness in areas of high background emission and stellar density, and find that it contributes significant uncertainty to the determination of cluster properties. We find that age determination using only near-IR (NIR) photometry has an uncertainty of similar to 3 Myr.