First VLBI observations of methanol maser polarisation, in G339.88-1.2

TL;DR

This paper presents the first VLBI polarisation observations of methanol masers in G339.88-1.2, revealing magnetic field orientations that challenge the disk model of maser environments.

Contribution

It introduces the first polarisation VLBI maps of methanol masers in the southern hemisphere, demonstrating a new technique and providing insights into maser environment models.

Findings

Magnetic field directions are inconsistent with the disk model for most emission.

First successful polarisation VLBI images of methanol masers in the south.

Technique confirms previous ATCA observations, opening new avenues for southern VLBI studies.

Abstract

We investigate class II methanol masers and the environment in which they form with the Long Baseline Array (LBA). Using full polarisation VLBI, we're able to measure the magnetic field directions so as to distinguish between the two main models of the environment in which methanol masers form: disks or shocks. We present polarised images of the methanol maser source G339.88-1.2, made with the LBA at 6.7-GHz. With these first polarisation maps made with the LBA, which successfully reproduce observations with the ATCA confirming the new AIPS code, a new technique for Southern VLBI is opened. The magnetic field directions found are inconstant with methanol masers arising in disks for the majority of the emission.