OH30.1 18cm OH Masers MERLIN

A set of 16 images for the OH 1612 MHz maser emission from the OH/IR star OH 30.1-0.7. Each image shows the distribution of the maser emission at a given velocity and corresponds to a cut through the circumstellar envelope. The colours represent the intensity of the maser emission. The strongest emission occurs from unresolved cap-like regions at the front and back of the envelope (first and last images). At intermediate velocities, weaker emission is detected from rings which are centred on the stellar position. The radii of the rings increases towards the central velocity in just the way expected for a spherical shell of constant radius. However at some velocities the well resolved images show the masers to be located within several arc-like filamentary structures. These define knotty regions of enhanced gas density where the maser emission is strongest.
Chapman(AAO/ATNF), Killeen(ATNF) and van Langevelde(JIVE)