Constrain the transit locations through sodium sublimation modeling

Derive more reliable constraints on the orbital distances and periastron locations of transiting PDS 70 exocomets by developing sophisticated models of sodium release and sublimation for low-gravity bodies with unknown compositions in vacuum conditions.

Background

The observed radial velocities provide only broad constraints on the distances of the absorbing bodies, while estimates based on an equilibrium sodium sublimation temperature suggest that the comets may lie within approximately 0.05 au of PDS 70 during transit.

The paper emphasizes that this temperature estimate is not directly applicable to low-gravity exocomets in vacuum and that Solar System observations demonstrate sodium release at much greater distances. Consequently, the transit locations cannot yet be determined without a more physically realistic treatment of sodium sublimation, composition, sputtering, and tail production.

References

For these reasons, we are not yet able to further constrain where these comets are located when viewed in transit, and more sophisticated simulations of the sublimation of sodium are necessary to achieve this.

— Potential sublimating exocomets around the young star PDS 70  (2608.23208 - Novais et al., 24 Aug 2026) in Section “Periastron distances of transiting exocomets”