Séminaire - Fingerprints of the protosolar cloud collapse in the solar system - Francesco C. Pignatale

Mardi 11 février 2020 à 14 h 30

IMPMC, Salle des élèves, 2^e étage, 61 rue Buffon, Paris 5^e

Francesco C. PIGNATALE - Institut de Physique du Globe de Paris

Abstract

Primitive meteorites, or chondrites, are the relics of the first million years of the Solar System. They contain different solid phases formed in a disk of gas and dust, called a protoplanetary disk, which surrounded the young Sun. Among these solids, the oldest are Calcium-Aluminum-rich Inclusions (CAIs) dated 4567 million years. CAI precursors formed at temperatures above 1500° C by condensation. Such temperatures are expected near the young Sun. However, CAIs are most abundant in carbonaceous chondrites, which assembled far from the Sun. This meteoritic hot/cold paradox has been a stumbling block for most of the Solar System's theoretical models. "Classic" models generally consider an isolated protoplanetary disk. However, CAIs were formed in such a short time (~ 0.2 Ma) that the protoplanetary disk was likely still being fed by a collapsing interstellar cloud.

In this seminar I will present results from our numerical simulations, where we coupled the most important chemical and dynamical processes of a cloud-star-disk system. Focusing on the formation and transport of refractory and less refractory material within a forming disk fed by a collapsing cloud we propose a solution to the long standing hot/cold paradox of chondrites. I will then explore heterogeneities of the short-lived radionuclide ²⁶Al that may have characterized the Solar System parent cloud and may compromise its use for relative age dating. In the final part of the seminar I will present preliminary results on the efficiency of planetesimal formation during the cloud collapse and related implications for meteorites and terrestrial planet formation. This may have bearings on the parent bodies of iron meteorites which may have formed contemporaneously with CAIs.