Hot Jupiters are exoplanets that are Jupiter-like in mass and size and orbit their host stars in very close proximity. Due to their unique physical properties (i.e., their large radii and small separation from their host stars), they have high transit probabilities establishing them as ideal candidates to study the atmospheric escape of close-in exoplanets. Their short orbital periods expose them to increased irradiation from their host stars, which causes them to lose their atmospheres. The helium (He I) 1083 nm line offers insight into the atmospheric escape of this selection of planets, which is likely to be significant in sculpting their population. By measuring the amount of excess absorption in this line during a transit, we are able to characterize the spatial extent of the planet's exosphere and its corresponding present-day mass loss rate. We used an ultra-narrow band filter to observe two transits of the gas giant HAT-P-18b, using the 200\" Hale Telescope at Palomar Observatory, and report the first-ever detection of He I in its atmosphere. We compare our results to Transiting Exoplanet Survey Satellite (TESS) data. With a J-band magnitude of 10.8, this is the faintest system for which such a measurement has been made, demonstrating the effectiveness of this approach for surveying mass loss on a diverse sample of close-in gas giant planets. As there has only been a handful of other helium outflow detections, our results directly contribute to the improvement of current atmospheric mass loss models. We used Wesleyan's High Performance Computing Cluster to successfully run Athena Æ, a 3D hydrodynamic code that simulates the atmospheric escape of hot Jupiters. We produced a simulation of a generic hot Jupiter to compare to our observational results and built the computational infrastructure at Wesleyan to enable future 3D hydrodynamic modeling of the extended atmospheres of exoplanets.
"},{"label":"Degree","value":["Bachelor of Arts with Departmental Honors"]},{"label":"Administrative Note","value":"Drupal Node ID: 24122