ELFT HÍRADÓ

["E. Forgacs-Dajka" <E.Forgacs-Dajka AT astro.elte.hu>]

                            Tisztelt Kolléga!

                                 MEGHÍVÓ


Szeretettel meghívjuk Önt az ELTE Csillagászati Tanszék és az
ELFT Csillagászati Szakcsoportja által szervezett
Országos Csillagászati Szeminárium következő előadására.



    Előadó neve:  Peter L. Biermann
                  (MPI for Radioastronomy, Bonn)

    Előadás címe:   Stellar evolution, supernovae, gamma ray bursts
                    and cosmic rays

    Előadás időpontja: 2004. február 25. (szerda) 14 óra 30 perc
    Előadás helye:     Budapest XI. Pázmány Péter sétány 1/A.
                       6. emelet 6.54 terem


Kivonat:
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Standard shock acceleration in the Interstellar Medium leads to
energies far below the feature in the cosmic ray spectrum usually
referred to as the knee, at 3*10^15 eV, where the spectrum
bends down by about 1/3.  There is one proposal published that
links this feature to the explosion of very massive stars, red
supergiants and Wolf Rayet stars.  In this proposal the knee is
predicted to be at near Z*10^15 eV approximately, and the
ankle, where the spectrum is in transition to the extragalactic
component, at 3Z*10^{17}$ eV, where Z is the charge of
the nucleus.  The spectrum is predicted to be E^-2.67 below the
knee, and E^-3.07 above the knee, with some expected error
range.  The observed features, at knee and ankle are so well
defined that the critical E/Z ratio must be very well defined in
Nature, and be common to all sites contributing to our cosmic ray
population.  This then leads back to the argument by Kardashev
(1964) that supernovae are powered by potential energy, and that
the energy is transmitted from rotation via magnetic fields to the
outside; this argument can be made quantitative.  Considering then
the abundances of cosmic rays this proposal requires that very
massive stars explode with 10^52 ergs, rather more than usually
assumed.  This is easily explained in Bisnovatyi-Kogan's picture, as
angular momentum loss during the star's evolution leads to a higher
explosion energy naturally.  This then leads to a final concept
that directly connects Gamma Ray Bursts with supernovae.  Tests
will be the abundances of the various chemical elements in cosmic
rays, the fraction of anti-protons, and the precise spectrum at
knee and ankle.


                 MINDEN ÉRDEKLŐDŐT SZERETETTEL VÁRUNK!


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                     ORSZÁGOS CSILLAGÁSZATI SZEMINÁRIUM

               Helyszíne: Budapest XI. Pázmány Péter sétány 1/A.
                          6. emelet 6.54 terem
               További információ: http://astro.elte.hu
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