Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/235930

Title

Short-lived radioactivity in the early solar system: the Super-AGB star hypothesis

Author(s)

Lugaro, Mario;  Doherty, Carolyn L.;  Karakas, Amanda I.;  Maddison, Sarah T.;  Liffman, Kurt;  Garcia-Hernandez, D. A.;  Siess, Lionel;  Lattanzio, John C.

Abstract

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⊙. 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.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Meteoritics and Planetary Science, Vol. 47, no. 12 (Dec 2012), pp. 1998-2012

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences;  0402 Geochemistry;  0403 Geology

Keyword(s)

Early solar system;  Short-lived radionuclides;  Solar system;  Super-AGB stars;  Super-asymptotic giant branch

Publisher

John Wiley & Sons

ISSN

1086-9379

Publisher URL

http://dx.doi.org/10.1111/j.1945-5100.2012.01411.x

Copyright

Copyright © The Meteoritical Society, 2012. The publisher does not allow Swinburne Research Bank to archive either the accepted manuscript of the published version of the article. However you can find an earlier version of the work at: http://arxiv.org/abs/1208.5816

Additional information

The authors acknowledge support from the CSIRO Astrophysics and Space Sciences (CASS)., the Spanish Ministry of Economy and Competitiveness under grant AYA-2011-27754, the Communaute francaise de Belgique - Actions de Recherche Concertees, and from the Institut d'Astronomie et d'Astrophysique at the Universite Libre de Bruxelles (ULB).

Peer reviewed