出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：A sample of massive young stellar objects was mapped at two epochs in the 6.7GHz methanol maser line using the EVN and monitored with the Torun 32m dish over a period of ∼14 months. Preliminary results show variations in the brightness of existing components but no large changes in the overall morphology of emission in the majority of sources during 2−6 years. A level of variability estimated from the single dish data was usually moderate in the most of targets. Remarkably high variability in the flux density and morphology of individual clusters was found in the source G33.641−0.228. In this object an arc-like structure of maser emission likely traces a passage of shock front.
