UVES spectra of the very young (~10^7 years) peculiar B-type star HR 6000
were analyzed in the near-UV and visual spectral regions (3050-9460 A) with the
aim to extend to other spectral ranges the study made previously in the UV
using IUE spectra. Stellar parameters Teff=12850K, logg=4.10, and xi=0km/s, as
determined from H_beta, H_gamma, H_delta Balmer profiles and from the Fe I, Fe
II ionization equilibrium, were used to compute an individual abundances
ATLAS12 model. We identified spectral peculiarities and obtained final stellar
abundances by comparing observed and computed equivalent widths and line
profiles. The adopted model fails to reproduce the (b-y) and c color indices.
The spectral analysis has revealed: the presence of emission lines for Mn II,
Cr II, and Fe II; isotopic anomalies for Hg, Ca; the presence of interstellar
lines of Na I at lambda lambda 3302.3, 3302.9, 5890, 5896 A, and of K I at
7665, 7699 A; the presence of a huge quantity of unidentified lines, which we
presume to be mostly due to Fe II transitions owing to the large Fe
overabundance amounting to [+0.7]. The main chemical peculiarities are an
extreme overabundance of Xe, followed by those of Hg, P, Y, Mn, Fe, Be, and Ti.
The most underabundant element is Si, followed by C, N, Al, S, Mg, V, Sr, Co,
Cl, Sc, and Ni. The silicon underabundance [-2.9] is the lowest value for Si
ever observed in any HgMn star. The observed lines of He I can not be
reproduced by a single value of the He abundance, but they require values
ranging from [-0.8] to [-1.6]. Furthermore, when the observed and computed
wings of He I lines are fitted, the observed line cores are much weaker than
the computed ones. From the present analysis we infer the presence of vertical
abundance stratification for He, Mn, and possibly also P.Comment: 14 pages, 8 figures, 6 tables, accepted for publication in A&
