Microlensing of circumstellar envelopes

II. Emission lines from radial and azimuthal flow during fold caustic crossings

¹ Dept. of Physics & Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
² Dept. of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, Wisconsin, 53706, USA

Corresponding author: H. M. Bryce, bryce@astro.wisc.edu

Received: 17 October 2002
Accepted: 2 December 2002

Abstract

This paper examines the line profile evolution due to bulk motion in circumstellar envelopes during microlensing fold caustic crossing events. These events have recently been shown to be a sensitive probe of stellar surface brightness profiles, thus providing a means – through both photometric and spectroscopic observations – to constrain and test stellar atmosphere models. Here it is demonstrated, through the examination of simplified line profiles, that spectroscopic studies of fold caustic crossings could also prove to be a powerful diagnostic of bulk motion in circumstellar envelopes.