Migration history of the super-eccentric planet TIC 241249530 b

Star system: TIC 241249530 | Distance from the Sun: 1103 light years

TIC 241249530 b is a rare, highly eccentric planet often described as a hot Jupiter progenitor. Orbiting a star at a distance that varies significantly, this planet is currently in the process of migrating toward its host star. This transition is driven by high-eccentricity migration, a process where a planet’s orbit is stretched into a very elongated shape, eventually shrinking and circularizing due to intense tidal forces.

The research examined how this planet arrived at its current state. By testing two specific models of tidal dissipation—the physical process by which gravitational forces convert orbital energy into heat within the planet—it was determined that equilibrium tides are the primary mechanism at work. Equilibrium tides occur when a planet responds slowly to the gravitational pull of its star, resulting in a predictable energy loss.

Conversely, the model of chaotic dynamical tides, which involves more rapid and turbulent internal responses to gravity, was found to be inconsistent with the current observations. The migration of TIC 241249530 b is triggered by von Zeipel-Lidov-Kozai oscillations, a phenomenon where the gravitational influence of a distant companion star in the system forces the planet's orbit to become increasingly elongated and tilted, eventually causing it to flip into a retrograde orbit.

Key findings
- TIC 241249530 b possesses a highly eccentric orbit with a value of 0.94.
- The planet follows a retrograde orbit, meaning it moves in the opposite direction to its star's rotation.
- Migration is driven by the gravitational influence of a distant binary star companion.
- Equilibrium tides effectively explain the planet's orbital evolution, whereas chaotic dynamical tides do not fit the observed data.

Scientific study

Case Study of a Super-eccentric Warm Jupiter Migrating via Equilibrium and Dynamical Tides (external link)