Periodic Flare of the 6.7 GHz Methanol Maser in IRAS22198+6336

TL;DR

This study reports the detection of periodic, intermittent flares in the 6.7 GHz methanol maser from IRAS22198+6336, with a 34.6-day cycle, providing insights into maser variability in star-forming regions.

Contribution

First detection of periodic, intermittent methanol maser flares in IRAS22198+6336, supporting the colliding-wind binary model for maser variability.

Findings

Six flares with a 34.6-day period observed.

Multiple spectral components vary synchronously with slight time offsets.

Flux ratio of flaring to quiescent states exceeds 30.

Abstract

We have detected periodic flares of the 6.7 GHz methanol maser from an intermediate-mass star-forming region IRAS22198+6336. The maser was monitored daily in 2011, 2012, and 2013. Six flares were observed with a period of 34.6 days. The variation pattern is intermittent, and the flux ratio of the flaring and the quiescent states exceeds 30. Such intermittent variation with the short period uniquely characterizes the variation of the IRAS22198+6336 maser. At least five spectral components were identified. The spectral components varied almost synchronously, but their peak times differed by 1.8 days. These characteristics can be explained by the colliding-wind binary model.