Radiative transfer codes

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- Authors:
P. Gouttebroze and N. Labrosse

  P. Gouttebroze

  N. Labrosse

- Purpose:
   PROM4 is designed to compute simple models of solar prominences. The models consist of plane-parallel slabs standing vertically above the solar surface. Each model is defined by 5 parameters: temperature, density, geometrical thickness, microturbulent velocity and height above the solar surface. It solves the equations of radiative transfer, statistical equilibrium, ionization and pressure equilibria, and computes electron and hydrogen level populations and hydrogen line profiles.

- More information:

see Gouttebroze, Heinzel and Vial (1993) A & A Sup. 99, 513 for the principle of modelling,

more details in Gouttebroze and Labrosse, 2000, Solar Physics 196, 349.

- Fortran files:
   Two versions of the code are proposed. They are written in Fortran 90, with free format:

 prom4.f , with text in English.

 prom4fr.f , with text in French.

  These codes need 64-bit arithmetic for real numbers. If it is not the default option of your compiler, it is necessary to include a compiler option insuring that reals will be coded on 64 bits (e. g., on IBM RS/6000 computers: xlf90 -qrealsize=8 prom4.f).

- Input files:

 intinc.dat  : principal file for incident intensities.

 intinc.dat.lines  : alternative file for "intinc.dat", with more weak absorption lines.

 intinc.dat.calc  : alternative file for "intinc.dat", with theoretical incident intensities.

 model.dat.exam  : an example for the "model.dat" file to be read by "prom4.f".

- Example of application:
   The code produces several output files, principally:

"resume.dat": a summary of physical and spectroscopic parameters (one half-page per model).

"profil.dat": a set of line profiles (plus the Lyman continuum), given as numbers. An auxiliary Fortran90 program profil.read  is proposed (as example) to read this file.

"profil.ps": the same set of profiles as "profil.dat", as a PostScript file (2 pages per model).

   For comparison purposes, the three output files corresponding to "model.dat.exam" are proposed as : resume.dat.exam , profil.dat.exam and profil.ps , respectively.

2. PROM5 : computation of intensities in hydrogen lines emitted by a model solar prominence.

- Purpose:
   PROM5 is similar to PROM4, but deals with prominence models whose physical properties are varying across the plane-parallel slab which represents the prominence. In particular, this allows the study of models including a cool core and a prominence-corona interface (PCI). The Fortran 90 code (free format) is contained in the file: prom5.f.

- Input files:
   To define the incident intensities, we use the same file intinc.dat as for PROM4. The physical model of prominence must be provided by the user, in a file named "model5.dat". This file is structured as follows: The first line contains the number of layers NZ and the altitude (in km) of the prominence above the solar surface. It is followed by NZ lines (one for each layer), containing 4 numbers each: temperature (K), pressure (dyn/cm2), depth (km) and microturbulent velocity (km/s). The depths are relative to a reference layer: they may be negative, but must be strictly increasing. Otherwise, negative or zero optical thicknesses would appear in the computations, causing execution failure. This file, "model5.dat", describes one half of the model only, the slab being assumed symmetrical.

- Output files:
   They are similar to that produced by PROM4. They are named "profil5.dat" for the ASCII file and "profil5.ps" for the PostScript file.

- Example:
   We provide a model of prominence with PCI. The core of the prominence has a thickness of 5000 km, a temperature of 10000 K, and a pressure of 0.02 dyn/cm2. It is surrounded by an interface whose temperature increases from 10000 to 100000 K over 3500 km. The temperature and the pressure vary linearly across the interface (the pressure vary from 0.02 to 0.1 dyn/cm2 for T=100000 K). The microturbulent velocity is equal to 5 km/s everywhere. This model has the advantage of matching approximately the integrated intensities observed in Lyman-alpha and Lyman-beta by OSO-8.
   The corresponding input and output files may be found there:

model5.dat

profil5.dat

profil5.ps