ExoExplorer Science Series: Briley Lewis (UCLA) & Julia Seidel (ESO)

The ExoExplorer Science Series presents talks by cohort members Briley Lewis (UCLA) & Julia Seidel (ESO) on April 15, 2022, from 11 AM - 12 PM Pacific / 2 PM - 3 PM Eastern. Connection information is below.

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Speaker: Briley Lewis (UCLA)

Title: Small Pieces of the Solar System: Dust, Ice, Pluto, and More

Abstract: Small debris, both in and out of our Solar System, provides a window into planet formation. Within our Solar System, we have the Kuiper Belt, icy and dusty debris beyond Neptune, as well as the asteroid belt and Oort Cloud. In 2015, the New Horizons mission provided the first up-close view of a Kuiper Belt Object when it visited Pluto. Pluto’s surface was revealed to be geologically complex, with volatile ices that are mobile on seasonal and longer timescales. Using New Horizons data, we investigated the distributions and movements of ices on Pluto’s surface. Detailed studies of solar system objects, like this work on Pluto’s surface geology, are complementary to our investigations into other planetary systems that harbor debris disks, sometimes referred to as “Exo-Kuiper Belts”. Both provide insight into the processes of planet formation. High-contrast imaging has been key in providing new information about this extrasolar debris, such as measurements of disk extent and morphological asymmetry — information that is not available from infrared excesses alone. However, we are currently limited in our ability to discern composition of debris disks, relying on color measurements and other coarse methods. As characterization capabilities continue to grow, we can expect further discoveries in these complementary fields, especially as new observatories like JWST and the ELTs provide even more highly detailed observations of both solar system objects and debris disks. I will also briefly discuss another small piece of our “solar system” of astronomy—science writing, and pedagogical best practices for integrating writing into physics and astronomy curricula.

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Speaker: Julia Seidel (ESO)

Title: Observing exoplanet winds

Abstract: ESPRESSO, as the first high-resolution spectrograph of the 2020s, has brought a significant increase in line precision, as shown with the re-observation of WASP-76b (Tabernero et al. 2020) and WASP-121b (Borsa et al. 2021), and allows us to move beyond the sole observation of the sodium doublet with a plethora of resolved spectral lines - probing different altitudes in the atmosphere.

Using the MERC code (Seidel et al. 2020a), a retrieval tool to determine winds in exoplanet atmospheres, the resolved lines can then be used to retrieve wind patterns directly. Compared to the analysis of the line shape on HARPS data only (e.g. Seidel et al. 2020a for HD189733b), the analysis of the line shape of ESPRESSO data permits to retrieve wind patterns in the upper atmosphere, but additionally also gives us unprecedented observational insights into the lower atmosphere from the line wings (Seidel et al. 2021). In this talk I will provide the community with a guide what we can, and can't. derive about atmospheric winds in exoplanet atmospheres with the current data quality and where our current limits lie as we move to smaller and cooler planets (Seidel et al. 2022). I will also provide a short introduction of ESPRESSO and other ESO instruments that might be useful for the cohort in future observing proposals.

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