Tim Hallatt

Astrophysicist

I am an astrophysicist at MIT. I focus on planet formation and the demographics of exoplanets. The goal of my work is to understand the extraordinary diversity of planetary systems in the Milky Way.

My science highlights planetary systems at the extremes to unveil the violent and high-energy processes shaping exoplanetary diversity.

Research

The Neptunian Final Parsec Problem
NEW

Close-in, Neptune-like planets pose a mystery: their demographics suggest they migrate from distant orbits, but the energy lost from their orbits during migration easily unbinds the planet structure. How do they survive? I show how planets' seismic oscillations tidally excited by their host stars may enable them to survive migration. Observations confirming my theoretical predictions would shed light on these enigmatic planets' structures, and the tidal physics sculpting their system architectures.

Uncovering the Origin of Desert Dwellers via Stellar Obliquities
NEW

Recently discovered 'desert dwellers' defy expectations by managing to survive at extremely close distances from their stars. I outline how observations can unravel their formation history by measuring the angle between host stars' spin axes and desert dwellers' orbital planes. If confirmed, our predictions may reveal the end stage of hot Jupiters' life cycle!

Revealing the Interiors of Gas Giants

A population of planets orbiting their stars at tighter distances than previously thought possible has recently been discovered ('desert dwellers'). I show that desert dwellers may be the remnants of giant planets laid bare through tidal destruction. Desert dwellers may therefore offer an unprecedented window into giant planet interiors!

Coupled Planetary Interior and Tidal Evolution

Planetary tidal evolution is complicated: planet structure dictates how tides operate in the planet, which in turn alter the structure and orbit. I developed a lightweight, accurate method to couple planet structure and dynamics. I used it to constrain the tidal physics operating inside hot, mid-sized planets!

Planet Formation in the Ancient Milky Way

Exoplanet demographics shift between the two dominant stellar populations of the Milky Way. I explore how the formation environment of planets in the Galaxy has differed across cosmic time, and how that may manifest in the planet distribution around some of the oldest stars in the Milky Way. This work has been featured in the press!

Sculpting the sub-Saturn Period Distribution via Atmospheric Evaporation

The exoplanetary orbital period distribution is a fossil record reflecting how planets form and evolve. I demonstrated that mid-sized planets' orbital period distribution can be sculpted by irradiation-driven atmospheric destruction. My theory predicts that such planets become less common around hotter stars, which has since been confirmed!

Explaining the Orbital Period Distribution of Gas Giants

Gas giant planet abundance grows rapidly with orbital period. I showed that this feature can be carved out if giant planets arrive at their final orbital locations via migration through their natal protoplanetary disks. Our theory predicts that the giant planet population grows more massive toward longer orbital periods.

The Galactic Dynamics of Interstellar Interlopers

Interstellar asteroids and comets pass through the solar system as they orbit the Galaxy, allowing us to study extrasolar bodies in exquisite detail. But can we understand where they may originate from, by bridging planetary and Galactic dynamics?

The Neptunian Final Parsec ProblemNEW

Uncovering the Origin of Desert Dwellers via Stellar ObliquitiesNEW