Light-element abundances of peculiar a stars |
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| Authors: | B N G Guthrie |
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| Institution: | (1) Royal Observatory, Edinburgh, Scotland |
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| Abstract: | Light-element abundances are compiled for six peculiar A stars (3 CenA,  2 CVn, HR 1732,v For,  Cnc, and 112 Her) with Heilines very weak for their colours. The abundances are interpreted on the theory that peculiar A stars were once secondaries in binary systems in which the primaries exploded as type II supernovae. During the explosions of the primaries, protons were accelerated to high energies (>20 MeV) in shock waves at the secondaries, and spallation of He, C, N, and O occurred. This was followed by the arrival of heavier elements from the primaries. Abundances on 2 CVn, HR 1732, andv For were subsequently modified by surface nuclear reactions involving protons and -particles accelerated to lower energies ( 10 MeV), probably by magnetic fields. Successive (,  ) reactions formed Si28 from Ne20, and (p, ) reactions acting on A40 and Ca40 may have contributed to the excesses of Cl observed on 2 CVn and HR 1732. These proposals have interesting implications with regard to the relative abundances of the iron-peak elements found on peculiar A stars and in the Solar System. |
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