Colloquium: Periodic variability of 6.7GHz methanol maser emission in high mass star-forming regions
© Image credit: Mateusz Olech (Space Radio-Diagnostics Research Centre, University of Warmia and Mazury)
High mass stars are very important in the chemical and physical evolution of our galaxy, yet their earliest stages of life are still not well understood. One of the earliest tracers of high-mass star-forming regions is the emission of Class II 6.7GHz methanol masers.
High resolution observations using Very Long Baseline Interferometry suggest that they emerge in the small portion of gas and dust on the transition between accretion disc and envelope. Due to the nature of stimulated emission they are highly sensitive to changes in local physical conditions. This gives us an opportunity to study in great detail the environment of HMYSO's.
In my talk I will present my work on investigating a small group of maser sources that was recently identified showing unusual, periodic behavior. Many theories have been proposed trying to explain this behavior but to this day there is no agreement on what process could cause periodicity.
Recent studies showing synchronicity of IR and 6.7 GHz emission and discovery of an unique source with alternating methanol and water maser flares gives us new insight into this problem.