With Lynne Hillenbrand and the PTF/iPTF collaboration, we have carried out a three-year, nightly cadence survey of the North America Nebula star-forming region. The relatively high cadence and long time coverage, combined with new techniques for analyzing time series, are giving us an unprecedented look at the aperiodic variability of thousands of young stars on timescales ranging from days to years.
While periodic variability has been used previously to study the rotation evolution of young stars, this is the first work to study aperiodic or "irregular" variability in a quantitative fashion for large numbers of stars. This work was possible in part because we had developed and tested new methods for measuring how quickly an irregularly sampled aperiodic light curve varies. Preliminary results suggest that most stars are dominated by variability occurring on timescales of only a few days; long-term accretion instabilities are either less common or are overwhelmed by shorter-term phenomena.
"Aperiodic Timescales Among Stars in the North America Nebula Complex", Findeisen, Krzysztof; Hillenbrand, Lynne; Ofek, Eran; Levitan, David; Sesar, Branimir; Laher, Russ; Surace, Jason, in prep.
"Simulated and Observed Performance of Timescale Metrics for Aperiodic Light Curves", Findeisen, Krzysztof; Cody, Ann Marie; Hillenbrand, Lynne, in prep.
"Disk-Related Bursts and Fades in Young Stars", Findeisen, Krzysztof; Hillenbrand, Lynne; Ofek, Eran; Levitan, David; Sesar, Branimir; Laher, Russ; Surace, Jason (2013), The Astrophysical Journal, 768, 93 ADS
"LightcurveMC: An extensible lightcurve simulation program", Findeisen, Krzysztof (2014), Astrophysics Source Code Library, record ascl:1408.012