The near-infrared linear polarization of directly imaged exoplanets and brown dwarf companions to main sequence stars
Abstract
The observed spectra of brown dwarfs and gas giant exoplanets are profoundly affected by the formation of clouds in their atmospheres, but the clouds' grain size distributions, depth variations, and horizontal structures remain largely unknown. Polarimetry is an emerging method for constraining both exoplanet and brown dwarf cloud models - scattering by aerosols in these objects' atmospheres induces polarization of their thermally emitted, near-infrared radiation. We present the results of a near-IR survey searching for linearly polarized thermal emission from a sample of two planetary mass companions and three brown dwarf companions to main sequence stars using the Gemini Planet Imager (GPI) and Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE). We find no polarized emission from the sample, and our deep observations allow us to probe the 0.1-1% linear polarization regime that typifies polarized free-floating brown dwarfs. We discuss the results of our survey in the context of the occurrence rates of polarized free-floating brown dwarfs as well as exoplanet cloud models and rotation rates.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23310504J