Probing the Atmospheres of Planets Orbiting Microlensed Stars via Polarization Variability

Abstract

We present a new method to identify and probe planetary companions of stars in the Galactic Bulge and Magellanic Clouds using gravitational microlensing. While spectroscopic studies of these planets is well beyond current observational techniques, monitoring polarization fluctuations during high magnification events induced by binary microlensing events will probe the composition of the planetary atmospheres, an observation which otherwise is currently unattainable even for nearby planetary systems.Comment: 7 pages, 2 figures. To appear in Astrophysical Journal Letter