Nuclear Uncertainties in the NeNa‐MgAl Cycles and Production of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcy

Abstract

Classical novae eject signiÐcant amounts of nuclear-processed material into the interstellar medium. Among the isotopes synthesized during such explosions, two radioactive nuclei deserve particular attention : 22Na and 26Al. In this paper, we investigate the nuclear paths leading to 22Na and 26Al production during nova outbursts by means of an implicit hydrodynamic code that follows the course of the thermonuclear runaway from the onset of accretion up to the ejection stage. New evolutionary sequences of ONe novae have been computed, using updated nuclear reaction rates relevant to 22Na and 26Al production. Special attention is focused on the role played by nuclear uncertainties within the NeNa and MgAl cycles in the synthesis of such radioactive species. From a series of hydrodynamic models, which assume upper, recommended, or lower estimates of the reaction rates, we derive limits on the production of both 22Na and 26Al. We outline a list of nuclear reactions that deserve new experimental investigations in order to reduce the wide dispersion introduced by nuclear uncertainties in the 22Na and 26Al yields.

First measurement of Mg isotope abundances at high redshifts and accurate estimate of Δα/α

“…Tables are only available in electronic form at http://www.aanda.org nuclide (José et al 1999(José et al , 2004, or in outflows from AGB-stars where the so-called hot-bottom burning operates (Karakas et al 2003(Karakas et al , 2006(Karakas et al , 2010. Direct measurements of the Mg isotopic ratio in different objects allow us to identify the sources of the chemical enrichment and thus to understand the chemical evolution of these objects.…”

Absolute determination of theNa22(p,γ)Sallaska1, Wrede2, Garcı́a3 et al. 2011Phys. Rev. C255340View full textAdd to dashboardCite

“…Indeed, this isotope has been observed in the Galaxy [6], but its long half life precludes the identification of its progenitor, and novae are only expected to make a secondary contri-bution to its Galactic abundance [7,8]. Other gammaray emitters can provide more direct constraints on nova models [9].…”

“…An observational upper limit of 3.7×10 −8 M ⊙ was set on the 22 Na mass in ONe nova ejecta with the COMPTEL telescope onboard the CGRO [10]. Currently, the maximum 22 Na mass ejected using ONe nova models is an order of magnitude below this limit [7,11] and corresponds to a maximum detection distance of 500 parsecs using an observation time of 10 6 s with the spectrometer SPI onboard the currently-deployed INTEGRAL mission [12]. This suggests we are now on the verge of being able to detect this signal.…”

“…It is important to reduce uncertainties in the rates of key reactions that are expected to affect the production of 22 Na so that accurate comparisons can be made between observations and models [7]. For example, the production of 22 Na in novae depends strongly on the thermonuclear rate of the 22 Na(p, γ) 23 Mg reaction [4,7,16], which consumes 22 Na.…”

“…For example, the production of 22 Na in novae depends strongly on the thermonuclear rate of the 22 Na(p, γ) 23 Mg reaction [4,7,16], which consumes 22 Na. The thermonuclear 22 Na(p, γ) reaction rate in novae is dominated by narrow, isolated resonances with laboratory proton energies E p 300 keV.…”