Revised rates for the stellar triple-alpha process from measurement of C-12 nuclear resonances
Journal article, 2005

In the centres of stars where the temperature is high enough, three alpha-particles (helium nuclei) are able to combine to form C-12 because of a resonant reaction leading to a nuclear excited state(1). (Stars with masses greater than similar to0.5 times that of the Sun will at some point in their lives have a central temperature high enough for this reaction to proceed.) Although the reaction rate is of critical significance for determining elemental abundances in the Universe(1), and for determining the size of the iron core of a star just before it goes supernova(2), it has hitherto been insufficiently determined(2). Here we report a measurement of the inverse process, where a C-12 nucleus decays to three alpha-particles. We find a dominant resonance at an energy of similar to11 MeV, but do not confirm the presence of a resonance at 9.1 MeV (ref. 3). We show that interference between two resonances has important effects on our measured spectrum. Using these data, we calculate the triple-a rate for temperatures from 10(7) K to 10(10) K and find significant deviations from the standard rates(3). Our rate below similar to5 x 10(7) K is higher than the previous standard, implying that the critical amounts of carbon that catalysed hydrogen burning in the first stars are produced twice as fast as previously believed(4). At temperatures above 10(9) K, our rate is much less, which modifies predicted nucleosynthesis in supernovae(5,6).

PARTICLES

B-12

BETA-DECAY

NUCLEOSYNTHESIS

ELEMENTS

ASTROPHYSICS

STARS

Author

H. O. U. Fynbo

Aarhus University

C. A. Diget

Aarhus University

U. C. Bergmann

European Organization for Nuclear Research (CERN)

M. J. G. Borge

CSIC - Instituto de Estructura de la Materia (IEM)

J. Cederkall

European Organization for Nuclear Research (CERN)

P. Dendooven

Kernfysisch Versneller Institut

L. M. Fraile

European Organization for Nuclear Research (CERN)

S. Franchoo

European Organization for Nuclear Research (CERN)

V. N. Fedosseev

European Organization for Nuclear Research (CERN)

B. R. Fulton

University of York

W. X. Huang

University of Jyväskylä

J. Huikari

University of Jyväskylä

H. B. Jeppesen

Aarhus University

A. S. Jokinen

University of Helsinki

University of Jyväskylä

P. Jones

University of Jyväskylä

Björn Jonson

Chalmers, Applied Physics, Subatomic Physics

U. Koster

European Organization for Nuclear Research (CERN)

K. Langanke

Aarhus University

Mikael Meister

Chalmers

Thomas Nilsson

Chalmers, Applied Physics, Subatomic Physics

Göran Hugo Nyman

Chalmers, Applied Physics, Subatomic Physics

Y. Prezado

CSIC - Instituto de Estructura de la Materia (IEM)

K. Riisager

Aarhus University

S. Rinta-Antila

University of Jyväskylä

O. Tengblad

CSIC - Instituto de Estructura de la Materia (IEM)

M. Turrion

CSIC - Instituto de Estructura de la Materia (IEM)

Y. B. Wang

University of Jyväskylä

L. Weissman

European Organization for Nuclear Research (CERN)

Katarina Wilhelmsen

Chalmers, Applied Physics, Subatomic Physics

J. Aysto

University of Jyväskylä

University of Helsinki

Nature

0028-0836 (ISSN) 1476-4687 (eISSN)

Vol. 433 7022 136-139

Subject Categories

Subatomic Physics

DOI

10.1038/nature03219

More information

Latest update

9/10/2018