Nicolas Prantzos
Institut d'Astrophysique de Paris (Paris, France)
Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris
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| « Li, Be, B and Cosmic Rays in the Galaxy » |
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Nicolas Prantzos |
| The production and evolution of the light elements Li, Be and B in the Milky Way are reviewed, in the light of recent observational and theoretical developments. I will first present a pedagogical introduction to this multidisciplinary field, showing how observations in the 80ies and 90ies progressively complicated the relatively simple (and for that reason particularly appealing) theory introduced by Menneguzzi, Audouze and Reeves in the early 70ies. I will then argue that the currently popular idea that Galactic Cosmic rays are accelerated inside metal-rich superbubbles (which leads ``naturally" to the production of primary Be and B, as observed) encounters the same problems as the previously popular (and now discarded) idea of supernovae accelerating their own ejecta. A major challenge to theories of light element production is presented by the recent (and still preliminary) data suggesting a surprisingly high and quasi-constant abundance of Li6 in halo stars; attempts to explain such a high "plateau" will be critically examined. |
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vendredi 15 avril 2005 - 11:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |