Determination of L1157-B1 shock’s proper-motions

Abstract

This study investigates the proper motions of the B1 shock in the L1157 star-forming region, using two images of [SII] from the Nordic Optical Telescope obtained in two different epochs, in 2014 and in 2018. The goal was to enhance the understanding of shock dynamics by measuring the proper motions of knots within the shock structure, using cross-correlation technique. We identified a total of eight distinguishable knots. Our analysis revealed a general leftward movement in right ascension, while no clear trend was observed in declination. Notably, the most residual knots exhibited the highest velocities, pointing toward the nominal position of B1 protostellar shock, while those knots most linked to the collision remained stationary. The study highlights the need for extended observational periods to improve measurement precision