A planet population dichotomy from isotopic enrichment?

Seminar Date: 
07 Feb 2017 - 14:00
Speaker: 
Tim Lichtenberg
ETHZ

In the nascent solar system the decay heat from short-lived radioisotopes (SLRs), in particular the externally injected aluminum-26, determined thermal and geodynamical transformation of planetesimals and embryos and the degree of volatile loss by outgassing. The degree of heating in early planetary bodies is therefore intrinsically linked to the star formation environment of the solar system. Constraining the injection channel of the solar system and the statistical distribution of SLRs among planetary systems is therefore crucial to compare the planet formation pathway of the solar system to its stellar siblings. In this talk, I will discuss the relevance of intra-cluster enrichment mechanisms for the injection of SLRs in young star-forming regions and show how the pollution of planet-forming systems from supernova ejecta can distribute SLRs  across small to large clusters (100–10,000 stars). Depending on the cluster morphology the enrichment levels can vary considerably, allowing for a large fraction of enriched systems to exhibit excess abundances compared to the solar system.
 The supernova pollution mechanism can thus seed a variety of initial abundance levels and resulting radiogenic heating rates in planetary precursors. Finally, with emphasis on solar system-like SLR levels, I will demonstrate how these variations affected the thermomechanical evolution of planetesimals in our solar system and beyond.