Optics of Media

Leising, G.

doi:10.1016/b978-0-444-89916-3.50012-9

Cited by 3 publications

(2 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Gamma-ray line emission at 1.275 MeV from classical novae in the Milky Way remains to be positively detected. SMM, OSSE, and COMPTEL have, however, reported upper limits for several individual novae (Leising 1993;Iyudin et al 1995; see Fig. 10).…”

Section: Be and 22 Namentioning

confidence: 95%

Gamma‐Ray Line Emission from Radioactive Isotopes in Stars and Galaxies

Diehl¹,

Timmes²

1998

PUBL ASTRON SOC PAC

110

View full text Add to dashboard Cite

Our modern laboratory of nuclear physics has expanded to encompass parts of the universe, or at least our Galaxy. Gamma rays emitted by the decays of radioactive nuclei testify to the production of isotopes through nuclear processes in astrophysical events. We collect measurements of the Galactic g-ray sky in spectral lines attributed to the decay of radioactive 7 Be, 22 Na, 26 Al, 44 Ti, 56 Ni, 57 Ni, and 60 Fe. We organize and collate these measurements with models for the production sites in novae, supernovae, stellar interiors, and interstellar cosmic-ray interactions. We discuss the physical processes and the spatial distribution of these production sites, along with models of the chemical evolution of the Galaxy. Highlights of measurements made in the last decade include detailed images of the Galaxy in 26 Al radioactivity and detection of 56 Co and 57 Co from SN 1987A, 44 Ti from Cas A, and possibly 56 Ni from SN 1991T. The 26 Al mapping of recent Galactic nucleosynthesis may be considered as a new view on the entire ensemble of massive stars in the Galaxy. The local Cygnus region shows prominent radioactive emission from well-known stellar clusters, but the absence of g-rays from the closest Wolf-Rayet star, WR 11, in the Vela region is puzzling. SN 1987A studies in g-rays measure the radioactive powering of the supernova light curve directly, which will be particularly important for the dim late phase powered by 44 Ti. The 57 Ni/ 56 Ni isotopic ratio determinations from g-rays provide additional guidance for understanding SN 1987A's complex light curve and now appear to be uniformly settling to about twice the solar ratio. Cas A 44 Ti production as measured through g-rays presents the interesting puzzle of hiding the expected, coproduced, and large 56 Ni radioactivity. Core-collapse supernova models need to parameterize the inner boundary conditions of the supernova in one way or another, and now enjoy another measurement of the ejecta that is definitely originating from very close to the difficult regime of the mass cut between ejecta and compact remnant. Other relevant measurements of cosmic element abundances, such as observations of atomic lines from the outer shells of the production sites or meteoritic analysis of interstellar grains, complement the rather direct measurements of penetrating g-rays, thus enhancing the observational constraints of nuclear astrophysics models.

show abstract

Section: Be and 22 Namentioning

confidence: 95%

Gamma‐Ray Line Emission from Radioactive Isotopes in Stars and Galaxies

Diehl¹,

Timmes²

1998

PUBL ASTRON SOC PAC

110

View full text Add to dashboard Cite

show abstract

“…Through this mechanism, nearby ONe novae within a few kiloparsecs from the Sun may provide detectable c-ray Ñuxes. Several experimental veriÐcations of this c-ray emission at 1.275 MeV from nearby novae have been attempted in the last 20 yr, using balloon-borne experiments (Leventhal, MacCallum, & Watts 1977) and detectors on board satellites such as HEAO-3 (Mahoney et al 1982), SMM (Leising et al 1988), and CGRO (Leising 1993 ;Iyudin et al 1995), from which upper limits on the ejected 22Na have been derived. In particular, the observations performed with the COMPTEL experiment on board CGRO of Ðve recent Ne-type novae (Nova Her 1991, Nova Sgr 1991, Nova Sct 1991, Nova Pup 1991, and Nova Cyg 1992Iyudin et al 1995), as well as observations of standard CO novae, have led to an upper limit of 3.7 ] 10~8 for the 22Na mass ejected by any M _ nova in the Galactic disk.…”

Section: Introductionmentioning

confidence: 99%

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

José

Coc

Hernanz

1999

ApJ

158

View full text Add to dashboard Cite

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.

show abstract

Reflection and absorption studies on polypyrrole films electrochemically prepared with different electrolyte types

Turcu¹,

Brie²,

Leising³

et al. 1999

Synthetic Metals

View full text Add to dashboard Cite

Optics of Media

Cited by 3 publications

References 9 publications

Gamma‐Ray Line Emission from Radioactive Isotopes in Stars and Galaxies

Gamma‐Ray Line Emission from Radioactive Isotopes in Stars and Galaxies

Reflection and absorption studies on polypyrrole films electrochemically prepared with different electrolyte types

Contact Info

Product

Resources

About