Absorption-line cloud models: distribution of column densities and velocity profiles

Metal-absorption Column Densities in Fast Radiative Shocks

In this paper we present computations of the integrated metal-ion column densities produced in the post-shock cooling layers behind fast, radiative shock-waves. For this purpose, we have constructed a new shock code that calculates the non-equilibrium ionization and cooling; follows the radiative transfer of the shock self-radiation through the post-shock cooling layers; takes into account the ...

The Distribution of Absorbing Column Densities among Seyfert 2 Galaxies

We use hard X-ray data for an " optimal " sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local Universe. Of all Seyfert 2 galaxies in the sample, 75% are heavily obscured (N H > 10 23 cm −2) and about half are Compton thick (N H > 10 24 cm −2). Intermediate type 1.8–1.9 Seyferts are characterized by an averag...

Diffuse Molecular Cloud Densities from UV Measurements of CO Absorption

Sensitivity of solar off-limb line profiles to electron density stratification and the velocity distribution anisotropy

The effect of the electron density stratification on the intensity profiles of the H I Ly-α line and the O VI and Mg X doublets formed in solar coronal holes is investigated. We employ an analytical 2-D model of the large scale coronal magnetic field that provides a good representation of the corona at the minimum of solar activity. We use the mass-flux conservation equation to determine the ou...

BROAD P v ABSORPTION IN THE QSO PG 1254]047 : COLUMN DENSITIES, IONIZATIONS, AND METAL ABUNDANCES IN BROAD ABSORPTION LINE WINDS FRED HAMANN

This paper discusses the detection of P V jj1118, 1128 and other broad absorption lines (BALs) in archival Hubble Space Telescope spectra of the low-redshift BAL QSO PG 1254]047. The P V identiÐcation is secured by excellent redshift and proÐle coincidences with the other BALs, such as C IV jj1548, 1550 and Si IV jj1393, 1403, and by photoionization calculations showing that other lines near th...