Polarized Light from Exoplanets: The Key to Clouds and Hazes? Pushkar Kopparla Vijay Natraj Yuk Yung Matthew Wilcoxson

Polarization and Exoplanets UNPOLARIZED POLARIZED UNPOLARIZED Stam et al (2004)

Model Setup From Star To Earth 1. Create a model atmosphere and perform radiative transfer (with VLIDORT*) 2. Rotate polarization vectors into equatorial plane and sum over illuminated disc *Spurr et al (2013)

Model Setup 3. Repeat at various phases and rotate into Earth’s sky plane 4. Compare with observations! Berdyugina et al (2011)

Polarimetric Observations of HD 189733b -π 0 π Observations at 0.36 and 0.44 micron wavelength -π 0 π Berdyugina et al (2011)

Model Output: Maximum Polarization Rayleigh atmosphere Geometric albedo 0.5 Model Observations Berdyugina et al (2011)

Conclusions Polarized light from exoplanets contains information about atmospheric structure and orbital orientation. We show that simple Rayleigh scattering comes close to but cannot fully account for the observed polarization of HD 189733b.

End Longitude of Ascending Node (omega) planet Ω star To observer