Bibcode
Lugaro, Maria; Doherty, Carolyn L.; Karakas, Amanda I.; Maddison, Sarah T.; Liffman, Kurt; Garc´a-Hernández, D. A.; Siess, Lionel; Lattanzio, John C.
Bibliographical reference
Meteoritics & Planetary Science, Online Early
Advertised on:
9
2012
Citations
0
Refereed citations
0
Description
The composition of the most primitive solar system condensates, such as
calcium-aluminum-rich inclusions (CAIs) and micron-sized corundum
grains, show that short-lived radionuclides (SLR), e.g.,
26Al, were present in the early solar system. Their
abundances require a local or stellar origin, which, however, is far
from being understood. We present for the first time the abundances of
several SLR up to 60Fe predicted from stars with initial mass
in the range approximately 7-11 M&sun;. These stars evolve
through core H, He, and C burning. After core C burning they go through
a "Super"-asymptotic giant branch (Super-AGB) phase, with the H and He
shells activated alternately, episodic thermal pulses in the He shell, a
very hot temperature at the base of the convective envelope
(approximately 108 K), and strong stellar winds driving the
H-rich envelope into the surrounding interstellar medium. The final
remnants of the evolution of Super-AGB stars are mostly O-Ne white
dwarfs. Our Super-AGB models produce 26Al/27Al
yield ratios approximately 0.02-0.26. These models can account for the
canonical value of the 26Al/27Al ratio using
dilutions with the solar nebula of the order of 1 part of Super-AGB mass
per several 102 to several 103 of solar nebula
mass, resulting in associated changes in the O-isotope composition in
the range Δ17O from 3 to 20‰. This is in
agreement with observations of the O isotopic ratios in primitive solar
system condensates, which do not carry the signature of a stellar
polluter. The radionuclides 41Ca and 60Fe are
produced by neutron captures in Super-AGB stars and their meteoritic
abundances are also matched by some of our models, depending on the
nuclear and stellar physics uncertainties as well as the meteoritic
experimental data. We also expect and are currently investigating
Super-AGB production of SLR heavier than iron, such as 107Pd.
Related projects
Nucleosynthesis and molecular processes in the late stages of Stellar Evolution
Low- to intermediate-mass (M < 8 solar masses, Ms) stars represent the majority of stars in the Cosmos. They finish their lives on the Asymptotic Giant Branch (AGB) - just before they form planetary nebulae (PNe) - where they experience complex nucleosynthetic and molecular processes. AGB stars are important contributors to the enrichment of the
Domingo Aníbal
García Hernández