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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Characterizing the Light Scattering Properties of Exoplanet Cloud Analogs Through Laboratory and Modeling Endeavors

Colin David Hamill (20360691) 13 December 2024 (has links)
<p dir="ltr">A better understanding of how aerosols interact with light is imperative as space telescopes unveil more about exoplanet atmospheres. To better understand how realistically shaped cloud condensates scatter light, I updated and tested the Exoplanet Cloud Ensemble Scattering System (ExCESS), which measures the scattering intensity and polarization of an ensemble of particles with respect to scattering angle at visible wavelengths. I used ExCESS to measure the scattering of cubic and irregular cuboid potassium chloride (KCl) particles, a likely cloud species in warm (T = 500 - 1000 K) mini-Neptune exoplanets like GJ 1214b. I then outline my changes made to the radiative transfer model, <i>PICASO</i>, that allow for a user-friendly and accurate method to compute reflected light phase curves. With this new capability, I explore the reflected intensity of Kepler-7b assuming different cloud condensates and particle sedimentation efficiencies, and I find that the cloud condensates Al<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub> may contribute more to reflected light intensity than previously expected for hot Jupiters with heterogeneous dayside temperatures. In the final chapter, I input the laboratory data from ExCESS into the scattering functionality of <i>PICASO</i>. I compare single-wavelength (532 nm) reflected light phase curves of GJ 1214b created with rough scattering approximations to those created with robust non-spherical scattering approximations (ExCESS measurements and discrete dipole approximation). I find that two term Henyey-Greenstein phase functions, which act as a rough approximation to cloud scattering, may be useful for estimating the scattering of cubic and irregular particle shapes when rigorous laboratory measurements or non-spherical scattering approximations are unavailable.</p>

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