Polarization and SEDs from Microlensing of Circumstellar Envelopes

TL;DR

This paper explores how microlensing of circumstellar envelopes, especially around red giants, can reveal properties of dusty winds through polarization and spectral energy distribution measurements, offering new observational techniques.

Contribution

It introduces modeling of polarization light curves and SEDs from microlensing of dusty stellar envelopes, highlighting potential for new observational insights.

Findings

Polarization light curves can infer envelope properties.

Time-dependent SED modeling reveals dust wind characteristics.

Potential to measure variable polarization with specialized instruments.

Abstract

Microlensing surveys have proven to be tremendously fruitful in providing valuable data products for many fields of astrophysics, from eclipse lightcurves for substellar candidates to limb darkening in stellar atmospheres. We report on a program of modeling observables from microlensing of circumstellar envelopes, particularly those of red giant stars that are the most likely to show finite source effects. We will summarize work for how polarization light curves can be used to infer envelope properties and will describe recent modeling of the time dependent spectral energy distributions (SEDs) for microlensing of dusty winds. One of the most exciting developments is the possibility of measuring variable polarization from microlensing in a suitable source using the RINGO polarimeter at La Palma. Also quite interesting is the possibility of probing a dusty wind using IRAC data for a suitable source in the event that Spitzer has a ``warm'' cycle.