科研之友
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摘要
We present here the application of a model for a mass circulation mechanism in between the H-burning shell and the base of the convective envelope of low-mass asymptotic giant branch (AGB) stars, aimed at studying the isotopic composition of those pre-solar grains showing the most extreme levels of O-18 depletion and high concentration of Mg-26 from the decay of Al-26. The mixing scheme we present is based on a previously suggested magnetic-buoyancy process, already shown to account adequately for the formation of the main neutron source for slow neutron captures in AGB stars. We find that this scenario is also capable of reproducing for the first time the extreme values of the O-17/O-16, O-18/O-16, and Al-26/Al-27 isotopic ratios found in the mentioned oxide grains, including the highest amounts of Al-26 measured there.
- 出版日期2017-5
- 单位Perugia
