Water masers in bowshocks: Addressing the radiation pressure problem of massive star formation

Abstract

Ejection activities in S255IR-SMA1 and AFGL 5142 were investigated by multiepoch VLBI observations of 22 GHz water masers, tracing bowshocks leading collimated jets. The history of ejections, revealed by the 3D maser motions and supplemented by the literature, suggests that these massive stars formed by episodic accretion, inferred via the accretion-ejection connection. This contribution centers on the role of episodic accretion in overcoming the radiation pressure problem of massive star formation -with maser…