Study of variable stars associated with maser sources: G025.65+1.05

Abstract

We report variation of K-band infrared (IR) emission in the vicinity of the G025.65+1.05 water and methanol maser source. New observational data were obtained with the 2.5 m telescope at the Caucasian Mountain Observatory (CMO) of Moscow State University on 2017–09–21 during a strong water maser flare. We found that the IR source situated close to the maser position had decreased brightness in comparison to archive data. This source is associated with a massive young stellar object (MYSO) corresponding to the compact IR source IRAS 18316–0602 (RAFGL 7009S). A similar decrease in K-brightness of the IR source close to the maser position was observed in March 2011 when the water maser experienced a period of increased activity. The dips in MYSO brightness can be related to the maser flare phases. Maser flares that are concurrent with dips in the IR emission can be explained if the lower IR radiation field enables a more efficient sink for the pumping cycle by allowing IR photons to escape the maser region.