Infrared variability, maser activity, and accretion of massive young stellar objects

TL;DR

This study links infrared variability with periodic methanol maser activity in a young stellar object, providing new insights into the connection between IR changes and maser periodicity.

Contribution

It presents the first IR light curve correlated with maser activity, demonstrating a direct relationship between IR and maser periodicity in a high-mass YSO.

Findings

IR and maser variability share the same period (~34.6 days)

IR light curve shape differs from maser flares

IR periodicity may be driven by accretion-related processes

Abstract

Methanol and water masers indicate young stellar objects. They often exhibit flares, and a fraction shows periodic activity. Several mechanisms might explain this behavior but the lack of concurrent infrared (IR) data complicates to identify the cause. Recently, 6.7 GHz methanol maser flares were observed, triggered by accretion bursts of high-mass YSOs which confirmed the IR-pumping of these masers. This suggests that regular IR changes might lead to maser periodicity. Hence, we scrutinized space-based IR imaging of YSOs associated with periodic methanol masers. We succeeded to extract the IR light curve from NEOWISE data for the intermediate mass YSO G107.298+5.639. Thus, for the first time a relationship between the maser and IR variability could be established. While the IR light curve shows the same period of ~34.6 days as the masers, its shape is distinct from that of the maser flares. Possible reasons for the IR periodicity are discussed.