The Magnetic Field Morphology of the Class 0 Protostar L1157-mm

TL;DR

This study reports the first polarization detection around the Class 0 protostar L1157-mm, revealing an hourglass magnetic field morphology aligned with the outflow, with estimated magnetic field strengths of 1.4 and 3.4 mG.

Contribution

It provides the first detailed polarization maps at multiple scales of a low-mass protostar, confirming an hourglass magnetic field morphology and estimating its strength.

Findings

Magnetic field lines are aligned with the outflow.

Detected an hourglass magnetic field morphology.

Estimated magnetic field strength between 1.4 and 3.4 mG.

Abstract

We present the first detection of polarization around the Class 0 low-mass protostar L1157-mm at two different wavelengths. We show polarimetric maps at large scales (10" resolution at 350 um) from the SHARC-II Polarimeter and at smaller scales (1.2"-4.5" at 1.3 mm) from the Combined Array for Research in Millimeter-wave Astronomy (CARMA). The observations are consistent with each other and show inferred magnetic field lines aligned with the outflow. The CARMA observations suggest a full hourglass magnetic field morphology centered about the core; this is only the second well-defined hourglass detected around a low-mass protostar to date. We apply two different methods to CARMA polarimetric observations to estimate the plane-of-sky magnetic field magnitude, finding values of 1.4 and 3.4 mG.