The impact of short-lived radionuclides and initial porosity on the thermomechanical evolution of early-formed planetesimals

The thermal history and internal struc- ture of chondritic planetesimals can have a crucial impact on the formation, evolution, and final composition of terrestrial planets. These critically depend on the internal bal- ance of heating versus cooling, which are mostly determined by the presence of short- lived radionuclides (SLRs), such as 26Al and 60Fe, as well as the heat conductivity of the material. The heating by SLRs depends on the for- mation time of the planetesimal and its size. It is often argued that the cooling history via heat conduction is determined by the porosity of the granular material, which un- dergoes dramatic changes via compaction processes. In this study we assess the combined effect of radiogenic heating by SLRs and initial porosity on the thermomechanical evolu- tion of young planetesimals and the impli- cations for terrestrial planet formation via 2D and 3D numerical simulations.