DIX Planetary Science Seminar

Pwyll and Manannán Craters as a Laboratory for Constraining Irradiation Timescales on Europa

We examine high spatial resolution Galileo/Near-Infrared Mapping Spectrometer observations of the young (∼1 My – ∼20 My) impact features, Pwyll and Manannán craters, on Europa's trailing hemisphere in an effort to constrain irradiation timescales. We characterize their composition using a linear spectral modeling analysis, and find that both craters and their ejecta are depleted in hydrated sulfuric acid relative to nearby older terrain. This suggests that the radiolytic sulfur cycle has not yet had enough time to build up an equilibrium concentration of H2SO4, and places a strong lower limit of the age of the craters on the equilibrium timescale of the radiolytic sulfur cycle on Europa's trailing hemisphere. Additionally, we find that the dark and red material seen in the craters and proximal ejecta of Pwyll and Manannán show the spectroscopic signature of hydrated, presumably endogenic salts. This suggests that the irradiation-induced darkening and reddening of endogenic salts thought to occur on Europa's trailing hemisphere has already happened at Pwyll and Manannán, thereby placing an upper limit on the timescale by which salts are irradiation reddened.

Validating TESS Planet Candidates with Palomar

The Transiting Exoplanet Survey Satellite (TESS) has discovered over 7000 planet candidates to date, of which only a few hundred have been confirmed as bona fide planets. Since the light curves of transiting planets should be nearly achromatic, confirmation studies routinely compare multi-color light curves as part of the candidate vetting process. Although these light curves can be more precise than the TESS data, they are typically not incorporated into a TESS candidate's false-positive probability (the probability that the observed transit signal has a non-planetary astrophysical origin). Here, we present high signal-to-noise infrared transit photometry of three Earth-sized TESS candidates obtained with the 200-inch Hale Telescope at Palomar Observatory. We develop a modified version of the TRICERATOPS software package in order to quantify the impact of multi-color transit photometry on the false-positive probabilities for each planet candidate.