Stellar Atmospheres
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Kevin Volk’s Stellar Atmospheres in C90.05

Kevin Volk incorporated three large grids of stellar atmosphere continua into Cloudy. The table star atlas, table star Rauch, and table star Werner commands use these. There are two steps involved in preparing the star files for use by Cloudy: first remap the original stellar atmospheres onto the Cloudy grid with the compile stars command, then use these files with the table star commands. The first step is only done once while installing Cloudy.

Preparing the Rauch stellar atmospheres

The procedure has changed a bit for C90.05 since Thomas Rauch now provides two sets of atmospheres.  These are for two abundance sets, solar and halo.

First obtain the tar files from Thomas Rauch’s Web site, http://astro.uni-tuebingen.de/~rauch/flux.html. You want two files, the solar abundances, and the halo abundances.  These have different names from the versions that were used by C90.04 and before.  The general format is temperature_gravity_abundances.wf.

Uncompress and explode these files in their own subdirectory. This will create a large number of stellar atmosphere files with names ending with the extension wf. Next execute Cloudy with the single command

compile stars Rauch initialize

This will create the two files rauch_halo.ascii and rauch_solar.ascii that are needed for the next step. Only these two files need be retained.

The Kurucz, Rauch, and Werner star files

Four files are needed to prepare to compile the stellar atmospheres, so that they can be used in model calculations. The rauch_halo.ascii and rauch_solar.ascii files were created above, and the werner.ascii, kurucz.list, and kurucz.ascii files come directly from the Cloudy Web site.

werner.ascii This is a plain ASCII version of the Werner and Heber (1991) grid of hot stellar atmospheres. These data extend from 10-5 Ryd through 182.25 Ryd.

kurucz.list This is a plain ASCII list of all files in the Kurucz (1991) grid.

kurucz.ascii This is the set of Kurucz (1991) atmospheres. The wavelengths of the grid are stored in nanometers as the first record. These data extend from 9.090 nm (10.0 Ryd) through 1.600 105 nm (5.7 10-4 Ryd).

rauch_halo.ascii and rauch_solar.ascii These are the sets of Rauch hot stellar atmospheres,  as produce with the table star rauch initialize command, described  above.

When the stars are compiled, as described next, four files, atlas.mod, rauch_solar.mod, rauch_halo.mod, and werner.mod, are created.

Compiling the star files

The stellar atmosphere files are very large, and reading them using Fortran sequential access would be very slow. Direct access is used to read these files in a timely manner. Direct access reads are a part of the ANSII Standard Fortran. Unfortunately the form of the file is machine specific, so that these files are not portable, although the code used to read or write them is portable.

It is necessary to have Cloudy compile the stellar atmosphere files before they can be used. This only needs to be done when the code is first installed, or if the energy mesh is changed. Follow these steps to compile the star files:
bulletMove the five files kurucz.ascii, kurucz.list, rauch_halo.ascii, rauch_solar.ascii, and werner.ascii  into a directory..
bulletExecute Cloudy with only the single command compile stars as input. Examine the resulting output for any comments indicating success or failure. I do this with the output coming to the screen so that I can monitor progress. This step typically takes about 15 minutes on my workstation.
bulletFour direct access files, atlas.mod, rauch_halo.mod, rauch_solar.mod, , and werner.mod will be created. These are the files which Cloudy must access to use the table star atlas, table star rauch, or table star Werner continua. Only these files need be kept.
bulletTo execute the code from other directories it is necessary to set the path to the directory containing these star files with the set path command described in part I of Hazy.

When doing later photoionization calculations, the code will stop before computing a model if it cannot locate the files when the corresponding table stars command is entered. The code also checks that the energy grids in the star files and the code itself agree, to confirm that the star files are appropriate for the current version of Cloudy.

Compiling only one of the star sets

Often only one or two of the sets of stellar atmospheres are needed, not the whole lot.   The only option was introduced to make this possible.  Following the instructions above but only get the files needed for the desired atmospheres.  Then execute the compile command with the only keyword, and another keyword identifying the stellar atmosphere, as follows:

compile only atlas
compile only werner
compile only rauch

Cleaning up after compilation

Only the atlas.mod, rauch_halo.mod,   rauch_solar.mod, and werner.mod are needed by Cloudy, and they only need to be created one time. The files werner.ascii, kurucz.list, rauch_halo.ascii,, rauch_solar.ascii, kurucz.ascii, and the *.wf atmosphere files can be deleted or compressed after the compilation is complete. They will only be needed again if the continuum binning within the code is changed. The Rauch *.wf files will never be needed again, unless one of the atmospheres is updated and it is necessary to recreate this set.

If the continuum binning is changed

The call to routine fill can be changed to change the continuum binning or resolution. This is described in a section of Part II of Hazy. If the continuum binning is changed then it will be necessary to recompile the star files, using the compile stars command, and then change the values of three related variables within the code. During the compilation of the star files the code will note the values of the variables nWerner, nRauch, and nAtlas that must be entered. Block data scalar must be edited to enter these new values where they appear in data statements.

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