Based on more than four weeks of continuous high cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA’s Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high quality, multi-wavelength light curves for young stellar objects (YSOs) whose optical variability is dominated by short duration
flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many
brief – several hour to one day – brightenings at optical and near-infrared (IR) wavelengths with
amplitudes generally in the range 5-50% of the quiescent value. Typically, a dozen or more of these
bursts occur in a thirty day period. We demonstrate that stars exhibiting this type of variability have
large ultraviolet (UV) excesses and dominate the portion of the u − g vs. g − r color-color diagram
with the largest UV excesses. These stars also have large Hɑ equivalent widths, and either centrally
peaked, lumpy Hɑ emission profiles or profiles with blue-shifted absorption dips associated with disk
or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated
by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Amongst the stars with the largest UV excesses or largest Hɑ equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations
associated with long-lived hot spots. We provide quantitative statistics for the average duration and
strength of the accretion bursts and for the fraction of the accretion luminosity associated with these
bursts