We present a detailed study of the complex ionization structure in a small (∼250 pc) extended narrow line region (ENLR) cloud near Centaurus A using the Multi Unit Spectroscopic Explorer. This cloud is located in the so-called outer filament of ionized gas (about 15 kpc from the nucleus) where jet-induced star formation has been suggested to occur by different studies. We find that, despite the...

Empirical ionization fractions of C IV, N V, Si IV, and empirical ionization plus excitation fractions of C III* and N IV* in the winds of 34 O stars and one B star have been derived. We combine the mass-loss rates derived from radio measurements and Ha with the line Ðtting of ultraviolet resonance lines and subordinate lines using the Sobolev plus exact integration (SEI) method. The dependence...

I N order to place the results of the recent studies of cosmic rays in appropriate perspective, let us recall very briefly their early history. It is well known how at the beginning of the present century C. T. R. Wilson,l and Elster and GeiteJ,2 showed that normal air is slightly ionized, and how McClennan and Burton3 at Toronto, and Rutherford and Cooke4 at Montreal showed by use of absorbing...

The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionizationparameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S iii]/[S ii] for six, ...

We have developed a three-dimensional radiative transfer method designed specifically for use with parallel adaptive mesh refinement hydrodynamics codes. This new algorithm, which we call hybrid characteristics, introduces a novel form of ray tracing that can neither be classified as long, nor as short characteristics, but which applies the underlying principles, i.e. efficient execution throug...