A study of the time variation of LSR velocity of recently discovered H 2O 6 16−5 23 masers

Abstract

We study the time variation in the LSR velocities of our recently discovered H 2O 6 16−5 23 masers using the results of three observational runs at yearly intervals with the 43 m and 13.7 m telescopes at Green Bank, USA and Delingha, China. It is found that the masers can be divided into two types. A small majority (Type A) shows alternation of structures, caused by the existence of several unresolved maser knots within the observing beam, with the LSR velocity offset dV restricted by the simple motion of the common exciting source. The rest (Type B) show large velocity differences DV between the epochs, indicating overall motion of the ensemble of knots. Acceleration of the exciting source and the pumping mechanism are involved in the latter type.