Detection of periodic flares in 6.7 GHz methanol masers G45.804-0.356
  and G49.043-1.079
  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 32m 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.
