Dodson, R.Ojha, R.Ellingsen, S. P.2020-04-152020-04-152004-07-01R. Dodson, R. Ojha, S. P. Ellingsen, High-resolution observations of 6.7-GHz methanol masers with the Long Baseline Array, Monthly Notices of the Royal Astronomical Society, Volume 351, Issue 3, July 2004, Pages 779–790, https://doi.org/10.1111/j.1365-2966.2004.07844.xhttps://doi.org/10.1111/j.1365-2966.2004.07844.xhttp://hdl.handle.net/11603/18048http://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2004MNRAS.351..779DWe have used the Australian Long Baseline Array (LBA) to produce milliarcsecond images of five sites of methanol (CH3OH) maser emission at 6.7 GHz. These are all sites that have linear morphologies at arcsecond resolutions, which have been hypothesized to be due to the masers forming in edge-on circumstellar discs. We find that a simple disc model cannot explain the observations. We discuss various alternatives, and suggest a new model that explains how linear velocity gradients can be produced in methanol masers that arise in planar shocks propagating nearly perpendicular to the line of sight.12 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2004 2020 Oxford University Press Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Text