Test whether evolutionary preprocessing can compact the neutral-carbon distribution

Determine whether an evolutionary history involving early small-grain-rich, FUV-photoevaporative truncation or dynamical truncation by a stellar encounter can produce a more compact neutral-carbon distribution while retaining the substantial carbon monoxide reservoir required by observations.

Background

The disk-evolution calculation assumes that small grains are depleted throughout the disk and uses prescribed transport, magnetic angular-momentum transport, and boundary conditions. These assumptions may produce an outer gas structure that is too extended and may explain the overly extended neutral-carbon emission. The authors therefore identify alternative early evolutionary histories as possible mechanisms for modifying the inherited outer boundary while preserving the long-lived primordial gas reservoir.

References

The latter remains uncertain because of the adopted transport prescription, magnetic angular-momentum transport, boundary conditions, and the assumed radial extent of small-grain depletion. Testing the robustness of the predicted distribution will require multidimensional irradiation calculations and a broader exploration of plausible outer-disk structures.

— Thermochemical constraints on a primordial-origin of gas-rich debris disks  (2608.22781 - Mitani et al., 24 Aug 2026) in Section 4.3, “1D disk evolution model”