Meetings & Events
ExoExplorer Science Series: Alex Polanski (U Kansas) & Lili Alderson (U Bristol)
Date:
March 8, 2024
The ExoExplorer Science Series presents talks by cohort members Alex Polanski (U Kansas) & Lili Alderson (U Bristol) on March 8, 2024, from 11 AM - 12 PM Pacific Standard / 2 PM - 3 PM Eastern Standard. Connection information is below.
Speaker: Alex Polanski (U Kansas)
Title: Exploring Exoplanetary Systems with the TESS-Keck Survey
Abstract: The present-day orbital architecture of planetary systems is a fossil record of the system's formation history. While transit surveys have provided us with numerous planetary systems, it is unable to determine the mass of a planet, its orbital eccentricity, and whether the system harbors planets with inclinations large enough to preclude them from transiting. Where the transit method falls short, radial velocity follow-up demonstrates its strength.
In this presentation, I will share the system architectures revealed by the TESS-Keck Survey: a significant radial velocity follow-up effort aimed at measuring the masses and orbital properties of 86 TESS Objects of Interest. My work represents the largest uniform analysis of TESS-discovered planets to date, resulting in mass and orbital constraints for 127 planets. This includes 12 non-transiting companions and precise constraints on orbital eccentricity, which are crucial for accurate dynamical modeling of these systems.
Additionally, I will highlight the importance of complimenting primary survey instruments, such as Keck/HIRES, with instruments of comparatively lower precision. This synergy leads to fuller phase space coverage, resulting in more precise measurements of critical orbital parameters, such as eccentricity.The present-day orbital architecture of planetary systems is a fossil record of the system's formation history. While transit surveys have provided us with numerous planetary systems, it is unable to determine the mass of a planet, its orbital eccentricity, and whether the system harbors planets with inclinations large enough to preclude them from transiting. Where the transit method falls short, radial velocity follow-up demonstrates its strength.
Speaker: Lili Alderson (U Bristol)
Title: Observing Atmospheres Across the Radius Valley
Abstract: The last decade of exoplanet exploration has a population of 1-3 RE short-period planets, with peaks in the population at sub-Neptune and super-Earth radii, and a “radius valley” in between. Based on bulk composition alone, the nature of these planets has remained elusive, but atmospheric observations offer a new window to explore their compositional diversity. The JWST COMPASS survey (Compositions of Mini-Planet Atmospheres for Statistical Study) will obtain transmission spectra of 11 such planets using JWST NIRSpec/G395H, building a critical link between atmospheric characterisation and planetary demographics. In this talk, I will present results from the first multi-planet system observed by the COMPASS program, with the 2.8–5.2μm transmission spectrum of the ~870K, 1.7RE super-Earth TOI-836b. We find that transmission spectra from two visits are consistent with one another, and that by combining both visits, we can narrow in on the potential metallicity and cloud properties of the planet. I will also compare TOI-836b to its exterior sibling planet, the sub-Neptune TOI-836c, and the wider implications for this radius valley straddling system. This work provides insight into planning future observations of high metallicity planets around bright host stars, given the noise properties of our data.
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