YSOVAR: mid-infrared variability of young stellar objects and their disks in the cluster IRAS 20050+2720

TL;DR

This study investigates mid-infrared variability of young stellar objects in IRAS 20050+2720, revealing high variability among embedded stars, periodicity in some sources, and links between variability characteristics and physical processes.

Contribution

It provides the first detailed analysis of mid-infrared variability in this cluster, highlighting differences between disk-bearing and diskless young stars and their variability behaviors.

Findings

70% of embedded cluster members are highly variable

33 sources show periodic variability mainly in 2-6 days

Long-term variability linked to accretion, short-term to extinction

Abstract

We present a time-variability study of young stellar objects in the cluster IRAS 20050+2720, performed at 3.6 and 4.5 micron with the Spitzer Space Telescope; this study is part of the Young Stellar Object VARiability project (YSOVAR). We have collected light curves for 181 cluster members over 40 days. We find a high variability fraction among embedded cluster members of ca. 70%, whereas young stars without a detectable disk display variability less often (in ca. 50% of the cases) and with lower amplitudes. We detect periodic variability for 33 sources with periods primarily in the range of 2-6 days. Practically all embedded periodic sources display additional variability on top of their periodicity. Furthermore, we analyze the slopes of the tracks that our sources span in the color-magnitude diagram (CMD). We find that sources with long variability time scales tend to display CMD slopes that are at least partially influenced by accretion processes, while sources with short variability time scales tend to display extinction-dominated slopes. We find a tentative trend of X-ray detected cluster members to vary on longer time scales than the X-ray undetected members.