Stellar Atmospheres in C94
Kevin Volk incorporated three large grids of stellar atmosphere continua into Cloudy, and another has since been added. The table star atlas, table star Rauch, table star Werner and table star costar 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 energy 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.
Download the Atlas and Werner stars
These are available here. The single file stars.tar.gz will explode into four files, kurucz.list, kurucz.ascii, werner.ascii, and stars.htm. Only the first three are needed.
These are for two abundance sets, solar and halo.
First obtain the tar files from Thomas Rauch’s Web site. The link http://astro.uni-tuebingen.de/~rauch/flux.html points to the top level for all the stellar atmospheres. At the time of this writing a new set of stellar atmospheres is being computed, and until it is ready you will need to use the "first generation" H-Ca set. 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 change to the directory with the star files and execute Cloudy with the single command
compile stars Rauch initialize
This will read in the large number of small files and create the two larger files rauch_halo.ascii and rauch_solar.ascii that are needed for the next step. Only these two files need be retained.
The CoStar spectra
These are developed by Daniel Schaerer and are described in Schaerer D., et al, 1996ab, A&A 310, 837 and A&A 312, 475, and Schaerer & de Koter (1997; A&A 322, 598). They are available on the web from http://www.stsci.edu/ftp/science/starburst/SdK96.html . Version 94.00 of Cloudy only uses the solar grid, while 94.01 can use both the solar and halo metalicities.
Version 94.00 You only want the file Sc1_costar_z020_lb.fluxes and must rename it to costar.ascii.
Six 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, the werner.ascii, kurucz.list, and kurucz.ascii files come directly from the Cloudy Web site, and costar.ascii from the STScI site described above.
werner.asciiThis 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.listThis is a plain ASCII list of all files in the Kurucz (1991) grid.
kurucz.asciiThis 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.asciiand rauch_solar.ascii These are the sets of Rauch hot stellar atmospheres, as produce with the table star rauch initialize command, described above.
costar.ascii - The set of CoStar stellar atmospheres.
When the stars are compiled, as described next, five files, atlas.mod, rauch_solar.mod, rauch_halo.mod, costar.mod, and werner.mod, are created.
Some of the stellar atmosphere files are very large, and reading them using sequential access would be very slow. Direct access is used to read these files in a timely manner.
It is necessary to have Cloudy compile the stellar atmosphere files before they can be used. This both rebins the atmospheres onto the current Cloudy energy grid, and converts it to a direct access binary format. This only needs to be done once when the code is first installed, or if the continuum energy mesh is changed. Follow these steps to compile the star files:
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.
Cleaning up after compilation
Only the atlas.mod, rauch_halo.mod, rauch_solar.mod, costar.mod, and werner.mod are needed by Cloudy, and they only need to be created one time. The files *.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.
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 on the compile command was introduced to make this possible. Follow the instructions above, although you only need to 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 stars only atlas
The code will only try to read the indicated atmosphere, and produce only that mod file.
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. The code checks that the energy grid within the compiled stellar atmosphere file agrees exactly with the codes internal grid, and will stop if they do not agree to within machine precision. If the continuum binning is changed then it will be necessary to recompile the star files, using the compile stars command.