Planet engulfment remains a possible cause for lithium enhancement in TOI-5882

Star system: TOI-5882 A | Distance from the Sun: 1367 light years

TOI-5882 is a subgiant star—a star in the later stages of its life—that is notably rich in lithium. This star hosts a massive brown dwarf, an object larger than a giant planet but smaller than a star, orbiting every 7.1 days. The high levels of lithium found in the star have led to the hypothesis that the star may have recently consumed a smaller planet, such as a super-Earth or a Neptune-sized world, whose material would alter the star's chemical signature.

To test this idea, researchers used complex computer modeling to simulate the movement of planets and the aging of the host star. They combined stellar evolution models with N-body simulations, which track the gravitational interactions between multiple objects over time. By testing various starting configurations for the system, they looked to see if a planet could realistically fall into the star in a way that aligns with the observed lithium levels.

The simulations show that while the star consuming a planet is the most likely result for many of these orbital setups, only 5 percent of the scenarios led to an engulfment that would match the short timeframe required to observe the lithium signature. Because this successful outcome only occurs in a specific, rare set of initial conditions, the theory remains a plausible explanation that cannot be ruled out, though it is not yet confirmed.

Key findings
- TOI-5882 is a lithium-rich subgiant star hosting a 22-Jupiter-mass brown dwarf.
- Simulations suggest planet engulfment is a possible origin for the observed lithium enhancement.
- Only 5 percent of tested scenarios resulted in an engulfment within the required time window.
- Further information about the system's early history is needed to confirm this scenario.

Scientific study

Dynamical constraints on planet engulfment as the origin of lithium enhancement in TOI-5882 (external link)