Disk-Related Bursts and Fades in Young Stars

TL;DR

This study uses a multiyear survey to analyze variability in young stars, revealing diverse burst and fade behaviors linked to circumstellar material and accretion processes.

Contribution

First multiyear survey providing detailed characterization of aperiodic variability and identifying potential short-timescale accretion instabilities in young stars.

Findings

41 stars with distinct bursts or fades identified

Fading behavior is roughly twice as common as bursting

Diverse light curve morphologies observed, with no clear classification

Abstract

We present first results from a new, multiyear, time domain survey of young stars in the North America Nebula complex using the Palomar Transient Factory. Our survey is providing an unprecedented view of aperiodic variability in young stars on timescales of days to years. The analyzed sample covers R_PTF = 13.5-18 and spans a range of mid-infrared color, with larger-amplitude optical variables (exceeding 0.4 mag root-mean-squared) more likely to have mid-infrared evidence for circumstellar material. This paper characterizes infrared excess stars with distinct bursts above or fades below a baseline of lower-level variability, identifying 41 examples. The light curves exhibit a remarkable diversity of amplitudes, timescales, and morphologies, with a continuum of behaviors that can not be classified into distinct groups. Among the bursters, we identify three particularly promising sources that may represent theoretically predicted short-timescale accretion instabilities. Finally, we find that fading behavior is approximately twice as common as bursting behavior on timescales of days to years, although the bursting and fading duty cycle for individual objects often varies from year to year.