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- Creators: School of International Letters and Cultures
- Creators: Butler, Nathaniel
For the second half of my thesis, I focused on characterizing the atmospheres of directly imaged exoplanets. In the first study Hubble Space Telescope data on HR8799, in wavelengths unobservable from the ground, provide constraints on the presence of clouds in the outer planets. Next, I present research done in collaboration with the Gemini Planet Imager Exoplanet Survey (GPIES) team including an exploration of the instrument contrast against environmental parameters, and an examination of the environment of the planet in the HD 106906 system. By analyzing archival HST data and examining the near-infrared colors of HD 106906b, we conclude that the companion shows weak evidence of a circumplanetary dust disk or cloud. Finally, I measure the properties of the low mass directly imaged planet 51 Eridani b. We combined published J, H spectra with updated LP photometry, new K1, K2 spectra, and MS photometry. The new data confirms that the planet has redder than similar spectral type objects, which might be due to the planet still transitioning from to L-to-T. Model atmospheres indicate a cooler effective temperature best fit by a patchy cloud atmosphere making 51 Eri b an excellent candidate for future variability studies with the James Webb Space Telescope.
High levels of surface ozone pollution have been shown to have adverse effects on human health and our environment. For at least the past decade, ozone concentrations in Phoenix, Arizona have been above the federal health standard, set in place by the Environmental Protection Agency. It is crucial that all factors contributing to rising tropospheric ozone levels within the Phoenix metropolitan area are analyzed to better understand this risk for future mitigation efforts. Consequently, the primary objective of this study is specifically to examine meteorological factors' influence on Phoenix’s ground level ozone by comparing days of ozone exceedances with ozone non-exceedances days over the course of 2010-2020. To carry out this research, various weather conditions for both exceedance and non-exceedance ozone days were studied using unpaired Student’s t-tests and Pearson product-moment correlation tests. The results of this study suggest that the most significant factors that are associated with the occurrence of surface ozone exceedances in Phoenix are wind speed and temperature, whereas the least significant variables are wind direction and sky conditions. This indicates that more stable synoptic conditions in which skies are clearer, allowing for higher temperatures and more stagnant air movement, are ideal for ozone production leading to an ozone exceedance. The results from this honors thesis will be useful as it will aid in greater understanding of the relationship between Phoenix’s surface ozone and weather, aiding future ozone forecasting.