Applicability of anomalous-heating mechanisms to lower-mass irradiated planets

Determine whether the anomalous-heating processes invoked to explain the inflated radii of highly irradiated giant planets operate with similar efficiency in lower-mass planets such as TOI-5646 b.

Background

The internal-structure retrieval for TOI-5646 b depends on the planet’s intrinsic luminosity, which is highly uncertain because its formation and evolutionary history are poorly constrained. Highly irradiated giant planets often exhibit radii larger than standard cooling models predict, suggesting an additional heat source that delays cooling or inflates the planet. The paper considers both standard secular cooling and anomalous heating as limiting scenarios, but notes that the anomalous-heating prescriptions were calibrated for hot Jupiters with masses above 0.5 Jupiter masses and may not apply directly to a lower-mass super-Neptune such as TOI-5646 b. Establishing whether comparable heating operates efficiently in such lower-mass, metal-enriched planets is therefore necessary for interpreting their inferred composition and evolution.