Photometric monitoring in {sigma} Ori cluster

We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate members of the low-mass cluster population, from 0.02 to 0.5M_{sun}_. We are sensitive to brightness changes on timescales from 10 minutes to two weeks with amplitudes as low as 0.004mag, and find variability on these timescales in nearly 70% of cluster members.

We identify both periodic and aperiodic modes of variability, as well as semi-periodic rapid fading events that are not accounted for by the standard explanations of rotational modulation of surface features or accretion. We have incorporated both optical and infrared color data to uncover trends in variability with mass and circumstellar disks.