Formation of chondrules in magnetic winds blowing through the proto-asteroid belt

Formation of chondrules in magnetic winds blowing through the proto-asteroid belt

Chondrite meteorites are believed to represent the building blocks of the solar nebula, out of which our solar system formed. They are a mixture of silicate and oxide objects (chondrules and refractory inclusions) that experienced extremely high temperatures, set in a matrix that remained relatively cold. The prevalence of chondrites suggests that they formed through a very general process, related to stellar and planet formation. The nature of this mechanism, however, remains obscure as astronomical observations of star-forming regions suggest a relatively cold environment. Here we show how refractory objects could have been thermally processed in a radially-extended wind, accelerated magnetically from the surfaces of a protostellar disc. In this scenario, refractory precursor aggregates are heated while being lifted in the wind, growing through amalgamation, and eventually becoming heavy enough to drop back to the disc, where they assemble with the matrix. We show that processing at radial distances of about 1-3. AU can produce temperatures in the appropriate regime to melt chondrules and explain their basic properties, while retaining association with the colder material that provides the chondrite matrix. This mechanism is very general, as these energetic winds are commonly associated with stellar formation.

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