Qualitative reproduction of stellar O maser morphology

I. Results at a single stellar phase

¹ Onsala Space Observatory, 43992 Onsala, Sweden
² Department of Physics and Astronomy, UCL, Gower Street, London WC1E 6BT, UK e-mail: jyates@star.ucl.ac.uk
³ Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, UK e-mail: mdg@saturn.phy.umist.ac.uk
⁴ Institute for Storage Ring Facilities, University of Aarhus, 8000 Aarhus C, Denmark e-mail: dfield@ifa.au.dk
⁵ Department of Physics and Astronomy, Iowa State University, Ames IA 50011-3160, USA e-mail: ghbowen@iastate.edu

Corresponding author: E. M. L. Humphreys, liz@oso.chalmers.se

Received: 9 May 2001
Accepted: 11 September 2001

Abstract

We attempt to reproduce the observed morphologies of stellar H₂O maser emission by combining a hydrodynamic pulsation model of a long-period variable (LPV) star with an H₂O maser model. These numerical simulations yield synthetic maser lineshapes and interferometry images as a function of stellar pulsation phase. The results at a single stellar phase are presented here for 22, 321, 325 and 183 GHz masers. We compare our simulated data with the observed features of stellar H₂O masers, and make predictions of the existence of new masers in the circumstellar environment. We also predict the appearance of 183, 321 and 325 GHz maser images which may be observable in future using the Atacama Large Millimetre Array (ALMA). These simulations correctly locate the shell of 22 GHz masers in the region of the circumstellar envelope (CE) in which material is being accelerated to form the steadily-outflowing stellar wind.