Rivoldini, Attilio ; Tosi, Nicola ; Lécaille, Manon ; Van Hoolst, Tim ; Trinh, Anthony ; Baland, Rose-Marie ; Yseboodt, Marie ; Xiao, Haifeng

Poster presented at Mercury 2026 – An International Meeting on Planet Mercury, Leuven, Belgium on 2026-09-01

Abstract: Interior structure inferences for Mercury based on geodetic data can be strongly affected by prior assumptions about the detailed thermal structure of the core. In particular, the presence of a conductive, thermally stratified layer in the upper core (CTSL) is often neglected, although it directly affects the core temperature profile and, consequently, inferences of core composition and inner-core radius. The upper CTSL is a key component of numerical dynamo simulations that can explain important features of Mercury’s magnetic field. Additional support for a CTSL also comes from thermal evolution studies that use constraints on dynamo activity in the core. In this study, we assess how assumptions about core composition, the present-day thermal state, and the CTSL affect Mercury’s annual libration amplitude, long-period libration, obliquity, and tidal Love numbers. To determine the present-day thermal state, we use results from whole-planet thermal evolution simulations that are consistent with assumptions about core composition and constrained by crustal thickness as well as past and present dynamo activity. We also investigate the effects of internal couplings and dynamical shape on libration and obliquity.

Funding: 3PRODPLANINT/3PRODPLANINT/3PRODPLANINT