An Abundance Analysis of 3 Centauri

Abstract

Abundances in 3 Centauri A (B4 lV or Vp) are derived, using gamma Pegasi (B2 IV) as a standard comparison star and the approximation of a single- layer atmosphere. The abundances of elements (P, Ca, Ga, and Kr) not observed or observed only weakly in gamma Pegasi are derived relative to Si in 3 Centauri A. C, Ne, Si, Ar, and Ca have normal abundances. He and O are underabundant by a factor of 6 in 3 Centauri A; N is overabundant by a factor of 5; P by a factor of l00; Fe by a factor of 4; and Kr by a factor of about l300. An identification not yet certain of Ga II leads to an overabundance of about 8000 for Ga. Upper limits for the abundances of Al, S, Cl, Zn, Ge, As, Se, Br, Rb, and Sr are derived. Of these, S is deficient by a factor of more than about 10. lt is likely that Ga and Kr are local abundance peaks but that other elements in the same region of the periodic table could be almost as overabundant without being detected spectroscopically. lt is conjectured that these abundance anomalies, together with the large concentrationmore » of He/sup 3/ reported previously, are produced by the acceleration of particles on the surface of 3 Cen A. H. W. Babcock did not detect a regular magnetic field in the star, although it is probably related to the manganese'' stars which have magnetic fields. (auth)« less