Detection of periodic flares in 6.7 GHz methanol masers G45.804−0.356 and G49.043−1.079

Abstract

Context. Periodicity in 6.7 GHz methanol maser sources is a rare phenomenon that was discovered during long-term monitoring programmes. Understanding the underlying processes that lead to periodic variability might provide insights into the physical processes in high-mass star-forming regions. Aims. We aim to identify and describe new periodic methanol masers. Methods. The observations were obtained with the Torun 32 m antenna. Time series analysis was conducted using well-proven statistical methods. Additionally, NEOWISE data were used to search for a correlation between infrared and maser fluxes. Results. We found two new periodic sources, G45.804−0.356 and G49.043−1.079, with periods of 416.9 and 469.3 days, respectively. For G49.043−1.079, infrared variability is simultaneous with methanol flares. Conclusions. A most likely cause of the periodicity in G49.043−1.079 is modulated accretion. For G45.804-0.356, the periodicity cannot be explained with the available data, and further research is needed.