Transits and Occultations of Hot Jupiters




Haynes, Korey

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Since the first discovery of an extrasolar planet less than two decades ago, astronomers have learned how to measure not only the masses, radii, and orbital elements of a wide range exoplanets (far exceeding the parameters of our own solar system), but also their atmospheric temperatures and chemical compositions. Even with plentiful observations, many questions remain unanswered. Measuring atmospheric abundances based on observed absorption features can answer questions about carbon-to-oxygen (C/O) ratios, but many of the literature results rely on broadband photometry, where multiple absorption features become blended, thus complicating interpretation. Combining measurements across a long spectral baseline using multiple different instruments can be a powerful lever for studying the spectral energy distributions (SEDs) of exoplanets, but there is often a lack of consensus between observing teams and instruments. Some differences may be due to genuine temporal variations in the exoplanet atmospheres, while others are more likely due to differences in instrument characterization and data analysis. Resolved spectra of exoplanets, particularly in the infrared, where strong features due to water, carbon monoxide, carbon dioxide, and methane are expected, could break model degeneracies and answer many questions about C/O ratios and pressure-temperature atmospheric structures. While not the first, Wide Field Camera 3 (WFC3) on the Hubble Space Telescope is the only current space-based opportunity to study spectrally resolved exoplanet atmospheres in the infrared. We focus on hot Jupiter type exoplanets, and use WFC3 (as well as ancillary data from Spitzer and ground based facilities) to try to break degeneracies between models, resolve past observing conflicts, and unambiguously determine these planets' atmospheric composition and structure. We discover unambiguous detections of water in exoplanet atmospheres, and the first spectroscopic evidence for a temperature inversion due to TiO in an exoplanet atmosphere.



Astronomy, Exoplanets, Transits