Princeton University Extrasolar Planet Discussion Group

Hot Jupiters can form through high-eccentricity tidal migration, where primordial Jovian planets are driven to near-unity eccentricities and then tidally circularized into short-period orbits. This pathway is well-studied in three-body systems, where a companion star induces von Zeipel–Lidov–Kozai (ZLK) oscillations. I explore how adding a fourth body alters this picture.

In “2+2” systems, where each star in a binary hosts a planet, mirrored ZLK migration can produce double hot Jupiters. We found that up to ~9% of binaries with one hot Jupiter could harbor a second, and blind searches should target twin binaries with pericenter distances of a few hundred AU. In “3+1” systems, an additional intermediate perturber such as a brown dwarf can help trigger secular chaos, exciting planetary eccentricities even in low mutual inclination configurations. We map out the parameter space where this is most effective and find that resulting hot Jupiters favor obliquities near 90°.

Finally, I turn to the atmospheric characterization of Jovian planets as a complementary tracer of their histories. Using high-resolution VLT/CRIRES+ spectroscopy, we perform atmospheric retrievals on 2M0249-0557 c, a gas giant in the β Pictoris moving group, as well as on two benchmark brown dwarfs. All three objects show near-solar compositions, indicating a top-down formation pathway for the planet.