Cosmic radioactivities

Radionuclides with half-lives ranging from some years to billions of years presumably synthesized outside of the solar system are now recorded in ``live'' or ``fossil'' form in various types of materials, like meteorites or the galactic cosmic rays. They bring specific astrophysical messages the deciphering of which is briefly reviewed here, with special emphasis on the contribution of Dave Schramm and his collaborators to this exciting field of research. Short-lived radionuclides are also present in the Universe today, as directly testified by the gamma-ray lines emitted by the de-excitation of their daughter products. A short review of recent developments in this field is also presented.Comment: Invited Review to appear in New Astronomy, 16 pages, 2 figure

The survival of 205Pb in intermediate-mass AGB stars

The now extinct 205Pb is a pure s-process radionuclide (t_{1/2} = 1.5x10^7 y) of possible substantial cosmochemical interest. As a necessary complement to the detailed theoretical study of the nuclear physics and astrophysics aspects of the 205Pb - 205Tl pair carried out by Yokoi et al. (1985), and to the recent calculation of the 205Pb production in Wolf-Rayet stars by Arnould et al. (1997), this paper addresses for the first time in some detail the question of the survival of this radionuclide in thermally pulsing AGB stars. This problem is made difficult by the high sensitivity to temperature and density of the rates of the weak interaction processes that are able to produce or destroy 205Pb. In view of this sensitivity, a recourse to detailed stellar models is mandatory. With the help of some simplifying assumptions concerning in particular the third dredge-up characteristics, some of which (like its depth) being considered as free parameters, predictions are made for the 205Pb contamination of the stellar surface at the end of a pulse-interpulse cycle following a series of a dozen of pulses in three different intermediate-mass stars (M=3M_sun,Z=0.02; M=6M_sun,Z=0.02; M=3M_sun,Z=0.001). It is concluded that the chances for a significant 205Pb surface enrichment are likely to increase with M for a given Z, or to increase with decreasing Z for a given M. More specifically, following the considered pulses at least, the enrichment appears to be rather unlikely in the 3M_sun star with Z=0.02, while it seems to be much more probable in the other two considered stars. It is also speculated that the (3M_sun,Z=0.02) star could possibly experience some 205Pb enrichment following later pulses than the ones considered in this paper.Comment: 10 pages, 10 figures, Latex A&A, ps file available at ftp://obsftp.unige.ch/pub/mowlavi/pbtl.ps; accepted for publication in A&

NACRE II: an update of the NACRE compilation of charged-particle-induced thermonuclear reaction rates for nuclei with mass number A<16A < 16

An update of the NACRE compilation [Angulo et al., Nucl. Phys. A 656 (1999) 3] is presented. This new compilation, referred to as NACRE II, reports thermonuclear reaction rates for 34 charged-particle induced, two-body exoergic reactions on nuclides with mass number $A<16$, of which fifteen are particle-transfer reactions and the rest radiative capture reactions. When compared with NACRE, NACRE II features in particular (1) the addition to the experimental data collected in NACRE of those reported later, preferentially in the major journals of the field by early 2013, and (2) the adoption of potential models as the primary tool for extrapolation to very low energies of astrophysical $S$-factors, with a systematic evaluation of uncertainties. As in NACRE, the rates are presented in tabular form for temperatures in the $10^{6}$ $\simeq\leq$ T $\leq$ $10^{10}$ K range. Along with the 'adopted' rates, their low and high limits are provided. The new rates are available in electronic form as part of the Brussels Library (BRUSLIB) of nuclear data. The NACRE II rates also supersede the previous NACRE rates in the Nuclear Network Generator (NETGEN) for astrophysics. [http://www.astro.ulb.ac.be/databases.html.]Comment: 86 figure

A compilation of charged-particle induced thermonuclear reaction rates

Low-energy cross section data for 86 charged-particle induced reactions involving light (1 less than or equal to Z less than or equal to 14), mostly stable, nuclei are compiled. The corresponding Maxwellian-averaged thermonuclear reaction rates of relevance in astrophysical plasmas at temperatures in the range from 10(6) K to 10(10) K are calculated. These evaluations assume either that the target nuclei are in their ground state, or that the target states are thermally populated following a Maxwell-Boltzmann distribution, except in some cases involving isomeric states. Adopted values complemented with lower and upper limits of the rates are presented in tabular form. Analytical approximations to the adopted rates, as well as to the inverse/direct rate ratios, are provided. (C) 1999 Elsevier Science B.V. All rights reserved

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

The origin of the light nuclides

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Contribution à l'étude de la nucléosynthèse des éléments lourds du système solaire et lors des phases avancées de l'évolution stellaire

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

La physique des étoiles : un défi pluridisciplinaire

Arnould Marcel. La physique des étoiles : un défi pluridisciplinaire. In: Bulletin de la Classe des sciences, tome 17, n°7-12, 2006. pp. 207-208

Contribution à l'étude de la nucléosynthèse des éléments lourds du système solaire et lors des phases avancées de l'évolution stellaire

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe