| Popis: |
Echelle spectra of the z = 1.58 broad absorption line (BAL) quasar, Q 0059—2735, show a wealth of absorption lines, mostly from iron-peak elements. Lines from the ground state and from metastable levels up to nearly 4 e.v. are seen. From the absorption line shapes and column densities, strong constraints can be obtained for the absorbing cloud geometry, its chemistry, density, temperature, and distance from the QSO nucleus. Cloud cross sections increase with outflow velocity. Excitation temperatures range from 4 000 K for the lowest velocity, low ionization condensations to 60 000 K for the higher velocity BAL clouds. The low velocity clouds lie between 2 and 10 pc from the central ionizing source and have electron densities that are between 106 and 3 108 cm−3. Ionization models suggest that iron in the absorbing clouds is overabundant with respect to carbon, but as the ground-based data do not reach Ly-α, the overall metallicity of these clouds with respect to hydrogen is still unknown. |
