scholarly journals Light Elements and Cosmic Rays in the Early Galaxy

1997 ◽  
Vol 488 (2) ◽  
pp. 730-748 ◽  
Author(s):  
Reuven Ramaty ◽  
Benzion Kozlovsky ◽  
Richard E. Lingenfelter ◽  
Hubert Reeves
Keyword(s):  
Cosmic Rays ◽  
Light Elements ◽  
Early Galaxy

Galactic Cosmic Rays and the Evolution of Light Elements

1998 ◽  
Vol 499 (2) ◽  
pp. 735-745 ◽  
Author(s):  
Martin Lemoine ◽  
Elisabeth Vangioni‐Flam ◽  
Michel Casse
Keyword(s):  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
Light Elements

scholarly journals Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements

2018 ◽  
Vol 68 (1) ◽  
pp. 377-404 ◽  
Author(s):  
Vincent Tatischeff ◽  
Stefano Gabici
Keyword(s):  
Cosmic Rays ◽  
Light Element ◽  
Cosmic Ray ◽  
Nuclear Interaction ◽  
Galactic Cosmic Rays ◽  
Light Elements ◽  
Halo Stars ◽  
The Standard Model ◽  
Low Metallicity ◽  
Galactic Cosmic Ray

In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.

scholarly journals Li isotopes in metal-poor halo dwarfs: a more and more complicated story

2009 ◽  
Vol 5 (S268) ◽  
pp. 201-210
Author(s):  
Monique Spite ◽  
François Spite
Keyword(s):  
Cosmic Rays ◽  
Big Bang ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Lithium Abundance ◽  
The Galaxy ◽  
Li Isotope ◽  
Low Metallicity ◽  
The Big Bang ◽  
Early Galaxy

AbstractThe nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis.The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the ν process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient) warm galactic stars should retain the signature of these processes if, (as it had been often expected) lithium is not depleted in these stars. The existence of a “plateau” of the abundance of 7Li (and of its slope) in the warm metal-poor stars is discussed. At very low metallicity ([Fe/H] < −2.7dex) the star to star scatter increases significantly towards low Li abundances. The highest value of the lithium abundance in the early stellar matter of the Galaxy (logϵ(Li) = A(7Li) = 2.2 dex) is much lower than the the value (logϵ(Li) = 2.72) predicted by the standard Big Bang nucleosynthesis, according to the specifications found by the satellite WMAP. After gathering a homogeneous stellar sample, and analysing its behaviour, possible explanations of the disagreement between Big Bang and stellar abundances are discussed (including early astration and diffusion). On the other hand, possibilities of lower productions of 7Li in the standard and/or non-standard Big Bang nucleosyntheses are briefly evoked.A surprisingly high value (A(6Li)=0.8 dex) of the abundance of the 6Li isotope has been found in a few warm metal-poor stars. Such a high abundance of 6Li independent of the mean metallicity in the early Galaxy cannot be easily explained. But are we really observing 6Li?

scholarly journals 5. Study of Cosmic Rays by Rockets and Sputniks in the U.S.S.R.

1960 ◽  
Vol 10 ◽  
pp. 710-712
Author(s):  
S. N. Vernov ◽  
A. E. Chudakov
Keyword(s):  
Cosmic Rays ◽  
Charged Particles ◽  
Light Elements ◽  
Primary Particles ◽  
In The Beginning ◽  
Electron Photon ◽  
Photon Component

In the U.S.S.R. the study of cosmic rays by rockets was started in 1947.In the beginning, with the help of Geiger counters the number of charged particles was measured, and the formation of the electron-photon component in the interaction of primary particles of cosmic rays with nuclei of light elements was investigated.

scholarly journals The Light Elements Be and B as Stellar Chronometers in the Early Galaxy

2000 ◽  
Vol 198 ◽  
pp. 425-431 ◽  
Author(s):  
Timothy C. Beers ◽  
Takeru K. Suzuki ◽  
Yuzuru Yoshii
Keyword(s):  
Galactic Cosmic Rays ◽  
Heavy Elements ◽  
Type Ii ◽  
Galactic Chemical Evolution ◽  
Light Elements ◽  
Promising Alternative ◽  
Stellar Ages ◽  
Individual Type ◽  
Interstellar Material ◽  
Early Galaxy

Recent detailed simulations of Galactic Chemical Evolution have shown that the heavy elements, in particular [Fe/H], are expected to exhibit a weak, or absent, correlation with stellar ages in the early Galaxy due to the lack of efficient mixing of interstellar material enriched by individual Type II supernovae. A promising alternative ‘chronometer’ of stellar ages is suggested, based on the expectation that the light elements Be and B are formed primarily as spallation products of Galactic Cosmic Rays.

scholarly journals Lithium-Beryllium-Boron and Oxygen in the Early Galaxy

2002 ◽  
Vol 12 ◽  
pp. 442-444
Author(s):  
Elisabeth Vangioni-Flam ◽  
Michel Cassé
Keyword(s):  
Interstellar Medium ◽  
Physical Process ◽  
Energy Cost ◽  
Massive Stars ◽  
Light Elements ◽  
History Of ◽  
Early Galaxy ◽  
Main Producer

AbstractOxygen is a much better evolutionary index than iron to follow the history of Lithium-Beryllium-Boron (LiBeB) since it is the main producer of these light elements at least in the early Galaxy. The O-Fe relation is crucial to the determination of the exact physical process responsible for the LiBeB production. Calculated nucleosynthetic yields of massive stars, estimates of the energy cost of Be production, and above all recent observations reported in this meeting seem to favor a mechanism in which fast nuclei enriched in He, C and O arising from supernovae are accelerated in superbubbles and fragment on H and He in the interstellar medium.

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