Poster Abstracts

Name/Affiliation:  Scott Wolk (Harvard-Smithsonian CfA)

Title:  Infrared Variability in Several Star Formation Regions

We present an analysis of mid-infrared time-series photometry for several clusters taken as part of the Spitzer Young Stellar Object variability program (YSOVAR). In the clusters L1688, IRAS 20050-2720 and GGD 12-15 we identify variability in several hundred stars ranging from Class I to Class III. The data have with photometric uncertainty better than 0.05 mag down to [4.5] ~ 15.5. We study the light curves and color trajectories of the sources in the monitored fields in detail. We investigate the variability and periodicity of the YSOs and find that they divide into observational classes which at a minimum include: 1) stochastic variables, 2) long-term variables, 3) periodic stars which vary in frequency of amplitude and 4) stars with periodic variability stable over long timescales. Some YSO variability defies simple classification. We describe how this variability may be due to both dynamic and rotational changes in inner disk structure and accretion rate.