Trigonometric distance and proper motions of H ₂ O maser bowshocks in AFGL 5142

Abstract

We present the results of multi-epoch VLBI (very long baseline interferometry) observations of water masers in the AGFL 5142 massive star-forming region. We measure an annual parallax of π = 0.467 ± 0.010 mas, corresponding to a source distance of |$D=2.14^{+0.051}_{-0.049}$| kpc. Proper motion and line-of-sight velocities reveal the three-dimensional kinematics of masers in this region, most of which associate with millimetre sources from the literature. In particular, we find remarkable bipolar bowshocks expanding from the most massive member, AFGL 5142 MM1, which are used to investigate the physical properties of its protostellar jet. We attempt to link the known outflows in this region to possible progenitors by considering a precessing jet scenario and we discuss the episodic nature of ejections in AFGL 5142.