Abstract
We consider the short-lived radionuclide (SLR) <sup>36</sup>Cl in calcium-aluminum-rich inclusions (CAIs) found in primitive meteorites with the solar wind implantation model. In this model, SLRs are produced via nuclear reaction with solar energetic particles (SEPs) interacting with gaseous targets in the protosolar atmosphere in T-Tauri stars. These SLRs are captured by the solar wind and then implanted in CAI precursor materials, which have dropped from the funnel flow leading onto the protostar. This method of incorporating SLRs into solar system materials is currently active in our solar system and has been measured with SLRs from the solar wind being implanted on the lunar surface. T-Tauri stars are capable of SEP fluxes <i>~</i>10<sup>5</sup> greater than contemporary SEP fluxes. Here we scale the production rate of <sup>36</sup>Cl to the ancient SEP activity. From the enhanced production rates and the refractory mass inflow rate at 0.06 AU from the protosun, we model the ancient <sup>36</sup>Cl content in CAIs. We find the initial isotopic ratio of <sup>36</sup>Cl/<sup>35</sup>Cl to range from about 1 × 10<sup>−5</sup> to 5 × 10<sup>−5</sup> and the concentration of <sup>36</sup>Cl to range from about 3 × 10<sup>13</sup> to 1.5 × 10<sup>14</sup> atoms g<sup>−1</sup>.
Highlights
Studies report evidence for the incorporation of the shortlived radionuclide (SLR) (T1/2 = 0.3 Myr) 36Cl into early solar system materials, including calcium-aluminum-rich inclusions (CAIs)
Relying upon Al-Mg systematics, Jacobsen et al [2] report that initial ratio of 36Cl/35Cl in wadalite from Allende would have been >8.7 × 10−3 had the initial 26Al/27Al ratio been the canonical value of ∼5 × 10−5
10Be and possibly other SLRs are produced by solar energetic particles (SEPs) reactions in the protosolar atmosphere of a more energetic T-Tauri sun, characterized by SEP fluxes many orders of magnitude greater than contemporary particle fluxes
Summary
The initial SLR ratios can be used to constrain early solar system evolution and conditions This is especially true in terms of solar luminosity and flaring characterization. Bricker and Caffee [4] proposed a solar wind implantation model for incorporation of 10Be in CAI precursor materials In this model, 10Be and possibly other SLRs are produced by SEP reactions in the protosolar atmosphere of a more energetic T-Tauri sun, characterized by SEP fluxes many orders of magnitude greater than contemporary particle fluxes. The SLRs are produced through nuclear reactions with these SEPs, and the irradiation produced SLRs are entrained in the solar wind and subsequently implanted into CAI precursor material.
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