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Session 49 - Galactic Radioactivity, 26A1 & Solar System Origin.
Oral session, Wednesday, June 11
North Main Hall F/G,

[49.05] The Origin of Chondrites and Extinct Radioactivities in the Solar System

F. H. Shu, H. Shang (UCB), T. Lee (Academia Sinica, Taiwan), A. E. Glassgold (NYU)

We will review current ideas concerning the formation of sunlike stars and planetary systems. In particular, we discuss the idea that the chondrules and CAIs found in chondritic meteorites might have been formed as solids entrained and melted in the bipolar wind that results from the interaction of the accreting protosolar nebula and the magnetosphere of the young protosun. Aerodynamic sorting and a mechanical selection for molten droplets that rain back onto the disk at planetary distances explain the size distributions and patterns of element segregation that we observe in carbonaceous and ordinary chondrties. Cosmic ray ions generated in the flares that accompany the general magnetic activity of the inner region may irradiate the precursor rocks before they are launched in the bipolar wind. Under reasonable scaling assumptions for the efficiency of the process in protostars, cosmic-ray bombardment suffices to generate the short-lived radionuclides ^26Al, ^41Ca, and ^53Mn at their inferred meteoritic levels.

Program listing for Wednesday