Mapping the Linearly Polarized Spectral Line Emission around the Evolved Star IRC+10216

TL;DR

This study uses spectro-polarimetric observations of molecular lines around IRC+10216 to map magnetic field structures in the star's envelope, revealing complex magnetic morphologies and demonstrating a new imaging technique.

Contribution

It introduces the application of spectro-polarimetric observations for tomographic magnetic field imaging in circumstellar environments, highlighting its feasibility and potential.

Findings

Detected linear polarization in multiple molecular lines.

Mapped magnetic field structures at ~450 AU from the star.

Identified complex magnetic field morphology in the envelope.

Abstract

We present spectro-polarimetric observations of several molecular lines obtained with the Submillimeter Array (SMA) toward the carbon rich AGB star IRC+10216. We have detected and mapped the linear polarization of the CO 3-2, SiS 19-18 and CS 7-6 lines. The polarization arises at a distance of ~450 AU from the star and is blueshifted with respect the Stokes I. The SiS 19-18 polarization pattern appears to be consistent with a locally radial magnetic field configuration. However, the CO 3-2 and CS 7-6 line polarization suggests an overall complex magnetic field morphology within the envelope. This work demonstrates the feasibility of using spectro-polarimetric observations to carry out tomographic imaging of the magnetic field in circumstellar envelopes.