Millimeter polarisation of the protoplanetary nebula OH 231.8+4.2: A follow-up study with CARMA

TL;DR

This study uses CARMA polarimetric observations at 1.3mm to analyze the magnetic field structure in the protoplanetary nebula OH 231.8+4.2, revealing an organized magnetic field with a likely toroidal component aligned with the nebula's dark lane.

Contribution

It provides new high-resolution polarimetric data at 1.3mm that complements previous submillimeter observations, offering insights into the magnetic field configuration in the nebula.

Findings

Detected polarised emission with a mean fraction of 3.5%.

Identified an organized magnetic field structure, likely toroidal.

Aligned magnetic field with the nebula's dark lane.

Abstract

In order to investigate the characteristics and influence of the magnetic field in evolved stars, we performed a follow-up investigation of our previous submillimeter analysis of the proto-planetary nebula (PPN) OH 231.8+4.2 (Sabin et al. 2014), this time at 1.3mm with the CARMA facility in polarisation mode for the purpose of a multi-scale analysis. OH 231.8+4.2 was observed at ~2.5" resolution and we detected polarised emission above the 3-sigma threshold (with a mean polarisation fraction of 3.5 %). The polarisation map indicates an overall organised magnetic field within the nebula. The main finding in this paper is the presence of a structure mostly compatible with an ordered toroidal component that is aligned with the PPN's dark lane. We also present some alternative magnetic field configuration to explain the structure observed. These data complete our previous SMA submillimeter data for a better investigation and understanding of the magnetic field structure in OH 231.8+4.2.