Sheng-Yuan Liu (ASIAA), Igor Zinchenko (IAP/RAS), Yu-Nung Su (ASIAA)
Strong luminosities variations or bursts associated with low mass young stellar objects (YSOs) in the optical and infrared bands have been observed and attributed to stochastic accretion phenomena in the process of star formations. Similar luminosity variations were recently also observed in the millimeter and submillimeter wavelengths toward not only low mass YSOs but also massive star-forming complexes. In the talk, we present our ALMA observations of the massive star-forming region S255-SMA1, a putative disk-outflow system around a massive star exhibiting over the past few years a significant luminosity burst in the infrared, radio continuum as well as its associated methanol masers. Our ALMA observations revealed intensity variations in both dust continuum and molecular lines corresponding to the burst, which is possibly resulted from an excessive accretion event due to disk fragmentation.