February 12, 2021

The first ExoExplorers cohort presentations will be February 12 from 1-2 PM Pacific / 4-5 PM Eastern. Connection info is below.

Speaker: Caprice Phillips (OSU)

Title: "Detecting Biosignatures In Gas Dwarf Planet Atmospheres With JWST"

Abstract: No Solar System analog planet to super-Earths exists, a class of exoplanets with masses 2-10x Earth’s mass which can retain a hydrogen atmosphere. Super-Earth atmospheres can have different compositions from nitrogen and oxygen dominated atmosphere of Earth. The James Webb Space Telescope (JWST) will offer unprecedented insight into the atmospheric composition of potentially habitable super-Earths through transmission and emission spectroscopy. I will present work on the investigation of NH3 (ammonia, a potential biosignature) detectability on super-Earths with an H2-dominated atmosphere using the Mid-Infrared Instrument (MIRI) and the Near InfraRed Spectrograph (NIRSpec) on the upcoming JWST mission. We use a radiative transfer code, petitRADTRANS, to generate synthetic spectra of optimal targets for observations given their proximity to Earth (<50 pc), radii (1.7-3.36 Earth radii), and equilibrium temperature (< 450 K). I will review the constraints of the MIRI LRS Instrument (flux ratio contrast of host star and planet ~ 10^-4), and discuss optimal targets for this instrument. For NIRSpec, I explore how varying cloud conditions, mean molecular weights (MMWs), and NH3 mixing ratios affects spectral features. Finally, I will discuss the use of PandExo to simulate mock observations with JWST and the detection significance findings for ammonia features with transmission spectroscopy.

Speaker Samson Johnson (OSU)

Title "Science Enabled by the Roman Galactic Exoplanet Survey"

Abstract The Nancy Grace Roman Space Telescope (Roman) will perform its Galactic Exoplanet Survey when it launches in the mid-2020's. With this first space-based microlensing survey, Roman will be sensitive to planets with orbital separations from roughly 1 AU to those unbound from any host star with masses as low as ten percent that of Earth's. The Roman Galactic Exoplanet Survey will be similar in scale to the Kepler mission, and will produce statistics on exoplanet demographics vital in improving planet formation models that are otherwise inaccessible. In this talk, I will give a brief overview of the Roman Galactic Exoplanet Survey and how it will use microlensing to detect these planets. I will highlight some of the unique insights Roman will give us, including its ability to detect Earth-analog systems and what it can teach us about the presence of free-floating planets in our Galaxy.

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Meeting number (access code): 199 188 2346

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