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M.R. Meyer, T. Marscovetra, V. Ivanov, C. Kulesa, C. Meakin, E. Young (Steward Observatory, The University of Arizona)
Photometric variability studies can provide important diagnostics of the accretion processes and other activity often observed in young stellar objects (e.g. Skrutskie et al. 1996, AJ, 112, 2168; Herbst et al. 1994, AJ, 108, 1906). We have initiated an IR monitoring program of optically-invisible young stellar objects in several embedded young clusters. Our goals are to; i) detecting stellar rotation periods in extremely young embedded clusters; and ii) looking for a connection between stellar rotation and disk accretion. Photometric monitoring at 1.25 microns (J-band) can be used to search for spot-modulated light curves from which rotation periods can be derived. Nearly simultaneous 1.65 micron observations can be used to trace variations in circumstellar extinction inferred from the (J-H) color. Finally, 2.2 micron excess emission provides estimates of the continuum excess emission thought to trace disk accretion processes. This program takes advantage of the unique access to a 1-2m class telescope equiped with modern IR instrumentation and involves teams of graduate and undergraduate student observers. Here we present preliminary results for the embedded cluster associated with the NGC 2024 nebula. Significant variability has been detected in several sources which can be explained through a combination of changes in extinction and disk accretion properties.