First VLBI observations of methanol maser polarisation, in G339.88-1.26

Abstract

Aims.We investigate class II methanol masers and the environment in which they form with the Long Baseline Array (LBA).Methods.Using full polarisation VLBI, we were 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.Results.We present polarised images of the methanol maser source G339.88-1.26, 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. © 2008 ESO.