NGC 7538 IRS1: Interaction of a polarized dust spiral and a molecular outflow

TL;DR

This study combines multi-telescope observations to reveal a spiral pattern in dust polarization and molecular outflow around NGC 7538 IRS1, illustrating the dynamic interaction of infall and outflow processes in star formation.

Contribution

It provides the first detailed imaging of the interplay between a polarized dust spiral and molecular outflow in NGC 7538 IRS1, highlighting energy and angular momentum exchange.

Findings

Detection of a spiral dust pattern rotating over 180 degrees.

Evidence of outflow disrupting dense, clumpy medium.

Correlation between CO emission ridge and dust spiral.

Abstract

We present dust polarization and CO molecular line images of NGC 7538 IRS1. We combined data from the SMA, CARMA and JCMT telescopes to make images with 2.5 arcsec resolution at 230 and 345 GHz. The images show a remarkable spiral pattern in both the dust polarization and molecular outflow. These data dramatically illustrate the interplay between a high infall rate onto IRS1 and a powerful outflow disrupting the dense, clumpy medium surrounding the star. The images of the dust polarization and the CO outflow presented here provide observational evidence for the exchange of energy and angular momentum between the infall and the outflow. The spiral dust pattern, which rotates through over 180 degrees from IRS1, may be a clumpy filament wound up by conservation of angular momentum in the infalling material. The redshifted CO emission ridge traces the dust spiral closely through the MM dust cores, several of which may contain protostars. We propose that the CO maps the boundary layer where the outflow is ablating gas from the dense gas in the spiral.