Uploaded April 2025 | Updated September 2026, 2 weeks ago
Grant Weldon is part of the 2025 NASA ExoExplorers cohort, a program that aims to enable the professional development of graduate students and/or postdocs in exoplanet research (“ExoExplorers”).
The ExoExplorers program, sponsored by NASA’s Exoplanet Exploration Program Office and the ExoPAG Executive Committee, will focus on the professional development of ~10 graduate student and/or postdoc researchers (“ExoExplorers”) at US and international institutions. Each member of the cohort will be featured in a webinar that will be live-streamed to the exoplanet community, helping to increase their visibility within the field and build internal and external research networks. The cohort will also learn from the experiences of established exoplanet researchers and engineers in the field (“ExoGuides”) via a combination of tailored presentations and small group discussions.
Talk title: The dynamical origins of giant planet eccentricities
Abstract: A rich diversity of extrasolar planetary systems has been discovered in recent decades, with many displaying unexpected architectures that challenge theories of planet formation informed by the Solar System. In particular, many giant planets have high orbital eccentricities, and many others orbit extremely close to their host stars. A proposed solution to both of these puzzles is high-eccentricity migration, in which an initially distant “cold” Jupiter is excited to high eccentricities, allowing for tidal interactions during close passages that drag the planet onto a close-in “hot” orbit. Secular (long-term) perturbations from a third body of planetary or stellar nature are a potential source of the eccentricity excitations, a phenomenon known as the Eccentric Kozai-Lidov (EKL) mechanism. I will discuss novel insights into the three-body problem that provide a new analytical understanding of the eccentricity evolution of planets subject to EKL from a distant perturber. Then, I will discuss recent work to characterize the effect of EKL from stellar companions on the giant planet population. We perform a population synthesis study of cold giant planets in stellar binaries, including the additional effects of tides, general relativity, and stellar evolution. The eccentricity distribution of the cold Jupiters is calculated, considering that planet-planet scattering may generate modest eccentricities on ~Myr timescales before EKL shapes the distribution on ~Myr-Gyr timescales. We find that the simulated eccentricity distribution is statistically consistent with the observed sample, suggesting that the EKL mechanism in stellar binaries may play an important role in driving the eccentricities of cold Jupiters and contributing to the formation of hot Jupiters.
Grant Weldon is part of the 2025 NASA ExoExplorers cohort, a program that aims to enable the professional development of graduate students and/or postdocs in exoplanet research (“ExoExplorers”).
The ExoExplorers program, sponsored by NASA’s Exoplanet Exploration Program Office and the ExoPAG Executive Committee, will focus on the professional development of ~10 graduate student and/or postdoc researchers (“ExoExplorers”) at US and international institutions. Each member of the cohort will be featured in a webinar that will be live-streamed to the exoplanet community, helping to increase their visibility within the field and build internal and external research networks. The cohort will also learn from the experiences of established exoplanet researchers and engineers in the field (“ExoGuides”) via a combination of tailored presentations and small group discussions.
Talk title: The dynamical origins of giant planet eccentricities
Abstract: A rich diversity of extrasolar planetary systems has been discovered in recent decades, with many displaying unexpected architectures that challenge theories of planet formation informed by the Solar System. In particular, many giant planets have high orbital eccentricities, and many others orbit extremely close to their host stars. A proposed solution to both of these puzzles is high-eccentricity migration, in which an initially distant “cold” Jupiter is excited to high eccentricities, allowing for tidal interactions during close passages that drag the planet onto a close-in “hot” orbit. Secular (long-term) perturbations from a third body of planetary or stellar nature are a potential source of the eccentricity excitations, a phenomenon known as the Eccentric Kozai-Lidov (EKL) mechanism. I will discuss novel insights into the three-body problem that provide a new analytical understanding of the eccentricity evolution of planets subject to EKL from a distant perturber. Then, I will discuss recent work to characterize the effect of EKL from stellar companions on the giant planet population. We perform a population synthesis study of cold giant planets in stellar binaries, including the additional effects of tides, general relativity, and stellar evolution. The eccentricity distribution of the cold Jupiters is calculated, considering that planet-planet scattering may generate modest eccentricities on ~Myr timescales before EKL shapes the distribution on ~Myr-Gyr timescales. We find that the simulated eccentricity distribution is statistically consistent with the observed sample, suggesting that the EKL mechanism in stellar binaries may play an important role in driving the eccentricities of cold Jupiters and contributing to the formation of hot Jupiters.
