Physical origin of protostellar disk brightness asymmetries

Determine whether the brightness asymmetries observed in embedded protostellar disks represent genuine physical structures or artifacts of radiative-transfer effects in optically thick disk regions.

Background

The visibility-plane models reproduce the overall morphology and large-scale asymmetries of most disks in the eDisk sample, but the authors cannot uniquely interpret these asymmetries physically. In optically thick regions, radiative-transfer effects can produce apparent brightness variations that resemble genuine substructures such as rings, gaps, or localized enhancements.

Resolving this ambiguity is important for determining whether the observed asymmetries provide evidence for physical disk structures and early planet-formation processes. The authors identify detailed radiative-transfer modeling and multi-wavelength observations, especially at 3 mm where emission is expected to be more optically thin, as approaches for distinguishing intrinsic structures from opacity-related effects.

References

While our models successfully capture the overall morphology of protostellar disks and account for large-scale asymmetries, we face a significant limitation: it remains challenging to determine whether these asymmetries represent genuine physical structures or if they are artifacts arising from radiative transfer effects in optically thick regions of the disk.

— Early Planet Formation in Embedded Disks (eDisk). XXIV: Systematic Investigation of Disk Structures based on Visibility Analysis  (2608.19364 - Narang et al., 19 Aug 2026) in Section 5, Discussion

However, some of the spiral-like residuals present in the axisymmetric model remain, leaving open the possibility that a spiral is present.

— Dust Substructures and Line Perturbations driven by a Forming Planet in J16120  (2609.05366 - Sierra et al., 4 Sep 2026) in Section 2.2.2, 'Eccentric dust disc'