AAS 198th Meeting, June 2001
Session 22. A Variety of Stellar Properties
Oral, Monday, June 4, 2001, 10:00-11:30am, C211

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[22.03] Polarization Light Curves from Microlensing of Extended Spherical Envelopes

R. Ignace (University of Iowa)

The basic idea of microlensing as a means of resolving the sources in lensing events is introduced. Focus is given to polarimetric observations during a microlensing event. Although an unresolved spherical source yields no net polarization, lensing leads to a transient polarimetric signature by virture of selective amplification. Results are presented for a simplified spherical envelope. The lensing light curve is sensitive to the density distribution in the envelope and the size of an inner cavity (as might occur for dust scattering in cool giant winds where the dust condensation radius is likely offset from the stellar photosphere). Of particular interest observationally is that peak polarization values from lensing of extended envelopes can reach considerably larger values than is to be expected from lensing of stellar photospheres only.

This research has been funded by a grant from NSF.

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