Determine the fate of angular momentum carried away by WASP-12 b mass loss

Determine whether angular momentum associated with gas lost from WASP-12 b is permanently removed from the planet’s orbit or is partly returned through subsequent interactions with the planet.

Background

The paper examines whether mass loss from WASP-12 b could provide a reservoir for the orbital angular momentum lost during inspiral. Escaping gas may reduce the planet’s orbital angular momentum, but the authors note that the subsequent dynamical interaction between the escaping material and the planet could potentially return some of that angular momentum.

This uncertainty affects whether mass loss can contribute meaningfully to the angular-momentum budget. The paper concludes that mass loss is expected to matter mainly near the current orbit, where the planet is strongly irradiated and close to Roche-lobe overflow, and therefore does not provide an obvious sink for angular momentum lost earlier in the inspiral.

References

Whether this angular momentum is permanently lost from the orbit, or partly returned through subsequent interactions with the planet, is uncertain.

— The Mysterious Inspiral of WASP-12b: Why Obliquity Tides Cannot Drive Orbital Decay  (2609.11925 - Lammers et al., 10 Sep 2026) in Section 5.1, “Other angular-momentum reservoirs”