Abundance analysis from the UV spectrum of the He-w star HR 6000.

Abstract

A high resolution spectrum of the He-w star HR 6000, covering the SW and LW regions, has been analyzed. A fully line-blanketed model atmosphere with parameters T(e) = 14,000 K, log g = 4, microturbulence xi = 2 km/s has been adopted. This model is in agreement with the photometric data and yields the same abundance for the Fe II and Fe III ions. By using the synthetic spectrum method, the observed lines were compared with the computed ones. An under-abundance is found of C, Al, Si, Mg, S, Sc, Co, Ni, and Zn, and an overabundance of Be, P, Cl, Ti, Mn, Fe, Ga. B, O, Cr have nearly solar abundances. Circumstellar (or interstellar) shortward-shifted components affect the strong resonance lines of the following ions: C II(1) 1334.535 A, O I(2) 1302.074 A, Mg II(1) 2795.523 A, 2802.698 A, Si II(3) 1304.369 A, Fe II(1) 2599.395 A.