Infrared photometry of red supergiants in young clusters in the Magellanic Clouds

We present broadband infrared photometry for 52 late-type supergiants in the young Magellanic Cloud clusters NGC 330, 1818, 2004, and 2100. Standard models are seen to differ in the temperature they predict for the red supergiant population by on the order of 300 K. It appears that these differences are most probably due to the calibration of the mixing-length parameter alpha(P) in the outermost layers of the stellar envelope. Because alpha(P) apparently depends on the model used, we do not quantitatively compare alpha(P) between models. Qualitatively, we find that alpha(P) decreases with increased stellar mass within standard models. We do not find evidence that alpha(P) depends on metallicity.