ELFT HÍRADÓ

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                                    MEGHIVO


                       2002. oktober 7., hetfo, 10 orakor
                 Az ELTE Pazmany Peter s. 1/A alatti epuleteben
                    az 2. emeleti 2.105 szeminariumi szobaban

                           Roberto Gallino professzor
                        (Dipartimento di Fisica Generale,
                         Universita' di Torino (Italy)):

                     "First generation stars in the Halo"


                                  Abstract

The chemical composition of very metal poor stars in the Galactic Halo
provides impressive constraints on local heterogeneities in the interstellar
medium from which those stars condensed. At least two different r-process   
distributions of heavy elements have been ascertained, a solar scaled
r-process composition for elements from Ba to Pb, and a distinct odd-even
r-process distribution in lighter elements from Ru to Pd. The few
observations of transuranic elements (Th, U) so far available raise the
possibility of a third r-process component beyond the magic neutron number
at N = 126.
Elements at the magic neutron peak N = 50, Sr, Y, Zr, cannot be ascribed to
the r process nor to the s process according to the classical theory.
Typical s-process signature is not present in unevolved Halo stars up to
[Fe/H]>-2, in agreement with recent calculations of s-process yields from
AGB stars and Galactic Chemical Evolution results.

Attachment: MEGHIVO.DOC
Description: Binary data