A highly collimated jet from the low mass proto-star NGC1333 IRAS 4B

TL;DR

This study uses high-resolution VLBA observations of water masers to reveal a highly collimated bipolar jet emanating from the low-mass protostar IRAS 4B, providing insights into jet launching mechanisms.

Contribution

First detailed VLBA imaging of water masers in IRAS 4B showing a highly collimated jet structure and measuring proper motions of maser spots.

Findings

Water masers trace a highly collimated bipolar jet.

Maser spots move at 10-50 km/s along the jet.

Active maser emission lasts less than four weeks.

Abstract

We imaged the protostars of the nearby region NGC1333 IRAS 4 in the water maser line at 22.2 GHz by using the VLBA in phase referencing at milliarcsecond scale over four epochs spaced by one month to measure proper motions. We measure the absolute positions and proper motions of the H2O spots to investigate the kinematics of the region from where the jet is launched. Two protostars (A2 and B) have been detected in a highly variable H2O maser emission, with an active phase shorter than four weeks. A 70 AU chain of several maser spots, very well aligned, has been observed close to the B protostar. The apparent proper motions have been derived, finding that the H2O spots are moving along the N-NW direction with projected velocities between 10 and 50 km/s. We conclude that in IRAS 4B, water maser trace a highly collimated bipolar jet clearly associated with the protostar.