Determine the dominant mechanism shaping the Neptunian desert

Determine whether the Neptunian desert is produced by a single global mechanism or by the interplay of multiple processes acting across the sub-Neptune, Neptunian, and Jovian regimes.

Background

The paper introduces the Neptunian desert as a pronounced deficit of short-period Neptunian planets extending across several planetary-size regimes. Formation, migration, and atmospheric-evolution theories predict different outcomes in these regimes, leaving unresolved whether one physical mechanism can account for the full desert or whether several coupled processes are required.

The authors investigate highly irradiated sub-Neptunes near the lower desert boundary, where high-eccentricity tidal migration and atmospheric escape offer competing or complementary explanations. The newly characterized TOI-426 and TOI-1839 systems provide observational constraints but do not resolve the global origin of the desert.

References

Today, it remains an open question whether the desert is produced by a single global mechanism or arises from the interplay of multiple processes acting across these regimes.

— Two extremely irradiated volatile-rich sub-Neptunes with companions in the TOI-426 and TOI-1839 systems: Insights into arrival and survival near the lower edge of the Neptunian desert  (2609.05413 - Castro-González et al., 4 Sep 2026) in Section 1, Introduction (opening paragraph)