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 18O depletion and high concentration of 26Mg from the decay of 26Al. 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 17O/16O, 18O/16O, and 26Al/27Al isotopic ratios found in the mentioned oxide grains, including the highest amounts of 26Al measured there.
A deep mixing solution to the aluminum and oxygen isotope puzzles in pre-solar grains
PALMERINI, SARA
Investigation
;TRIPPELLA, OSCARInvestigation
;BUSSO, Maurizio MariaInvestigation
2017
Abstract
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 18O depletion and high concentration of 26Mg from the decay of 26Al. 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 17O/16O, 18O/16O, and 26Al/27Al isotopic ratios found in the mentioned oxide grains, including the highest amounts of 26Al measured there.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
