Physical state of comet C/2023 A3 around perihelion

Determine the physical state of long-period comet C/2023 A3 (Tsuchinshan–ATLAS) around its 27 September 2024 perihelion, including whether its observed brightness anomaly and elevated apparent water-production rate resulted from progressive nucleus fragmentation or occurred while the nucleus remained close to a steady state and stable against tidal disruption, sublimation-driven failure, and rotational instability.

Background

The paper identifies the comet’s physical condition near perihelion as unresolved. One interpretation attributes the brightness anomaly and unexpectedly high apparent water-production rate to progressive fragmentation of the nucleus before perihelion. A contrasting interpretation holds that the comet remained approximately steady and that its nucleus was stable against several disruption mechanisms.

The paper suggests that unresolved icy grains or ice-bearing aggregates in the near-nucleus coma could provide an extended water source and might contribute to both the brightness anomaly and the elevated apparent water-production rate. However, the observations and modeling presented do not definitively resolve the competing interpretations of the comet’s perihelion physical state.