AAS 201st Meeting, January, 2003
Session 109. Fine Structure in Galaxies
Oral, Wednesday, January 8, 2003, 2:00-3:30pm, 613-614

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[109.06D] Gravitational microlensing as a diagnostic tool for stellar astrophysics

H. M. Bryce (University of Wisconsin -- Madison)

In recent years it has been demonstrated that gravitational microlensing can constrain the source models of galactic microlensing events via the so-called ``finite source effects''. This thesis explored the possibilities for extracting information about the source surface brightness profiles from microlensing lightcurves. Several aspects of finite source effects were examined, in particular the observational requirements necessary for stellar atmospheres to be studied in microlensing events. The ability of microlensing to distinguish between differing source surface brightness profiles and thus, the underlying stellar atmosphere models is discussed for realistic observational strategies. Both point mass lens and fold caustic crossing events are considered. Secondly the capability of microlensing to then distinguish between radial and non-radial surface brightness profiles was extensively examined. The microlensing signatures of starspots are of interest as not only could such detections constrain stellar atmosphere models but there are concerns that starspot signatures could mimic planetary microlensing lightcurves. Finally an investigation is made of the spectroscopic signatures of microlensing of circumstellar envelopes and the opportunities for using microlensing to diagnose bulk motion in these envelopes during caustic crossing events. This thesis represents research undertaken by the author as a PPARC student at the University of Glasgow. The author is currently supported by a NSF grant.

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