Internal 26Al-26Mg isotope systematics of a Type B CAI: Remelting of refractory precursor solids

The 26Al-26Mg systematics of this Leoville Type B CAI suggest it experienced a final melting event at ∼50 ka after the initial Al-Mg fractionation event. This may correspond to melting during the active protostar stage (known as “Class I”), during which sporadic high temperature heating events repeatedly affected refractory solids in the solar nebula.