Spatio-kinematics of water masers in the HMSFR NGC6334I before and during an accretion burst

Abstract

In 2015, the high-mass star-forming region NGC6334I-MM1 underwent an accretion burst. Using VERA, we monitored 22 GHz water masers before and during the accretion burst to observe the changes in the maser spatial and velocity distributions in the region. The masers in CM2-W2 and MM1-W1 displayed variability that could be attributed to the accretion burst. The bright masers in CM2-W2 were found to better trace the shock structure as the epochs progressed. The mean 3D speeds derived from the proper motions were 50 km/s and 54 km/s for the pre-burst and burst epochs respectively. High-velocity proper motions were found at the southern edges of the N-S (∼80 km s−1) and NW-SE (∼150 km s−1) bipolar outflows. The precise mechanism of the flaring of the water masers due to the accretion burst has yet to be investigated.