From chondrules to chondrites

Séminaire IPAG de Emmanuel Jacquet (Muséum national d’Histoire naturelle), jeudi 12 juillet 2018 à 11h00, salle Manuel Forestini IPAG

Primitive meteorites, or chondrites, are witnesses of the first millions of years of the solar system, when the proto-Sun was surrounded by a dusty gas disc. Several varieties of them are known but it remains controversial what relative time/place of accretion they represent and what fractionation mechanisms imparted their deviation from a solar composition. Chondrites are dominated by millimeter-size igneous spheroids called chondrules, whose formation context likewise remains an opaque mystery. Chondrules and chondrite composition are obviously intertwinned questions which need to be disentangled if a basic understanding of primordial solar system "geology" is to be gained. In this talk, collecting from previous observational and theoretical works, I will argue that chondrules formed from nebular precursors (aggregates of primordial protoplanetary disc condensates), but in reservoirs that had already fractionated and which subsequently underwent little mixing until accretion of the chondrite parent bodies.