README File for the Code Galaxy

First version: 12 Aug 1998 (CL)
Claus Leitherer, Daniel Schaerer, Jeff Goldader, Rosa Gonzalez-Delgado, Carmelle Robert, & Duilia de Mello

Last update: 22 Dec 2000 (CL)
Claus Leitherer, Alessandra Aloisi, Miguel Cervino, & Daniel Schaerer

Disclaimer: This code is distributed freely to the community. The user accepts sole responsibility for the results produced by the code. Although every effort has been made to identify and eliminate errors, we accept no responsibility for erroneous model predictions.
The code and the models should be referenced as Leitherer et al. (1999).

Download the source code

File structure
The package comes with quite a few files. Some are essential whereas others are not, and you can do without them.

  1. The README file -- you should read this first.
  2. galaxy.f -- this is the code. It is standard Fortran 77. Nothing fancy, and some software wizards may consider the coding pretty pedestrian. Keep in mind the code was written for ourselves and not as shareware for the community. The main goal was to make it easily understandable and to make the structure be driven by astrophysical requirements. Elegance and speed were not our prime concern.
  3. Makefile -- this file is used to compile the code. You may want to tailor this to your need.
  4. go_galaxy -- this is a script to run the code. Its most important purpose is to assign the directories where the auxiliary files reside. You may also want to modify this depending on your directory structure.
  5. save_output -- this is a script to save the output files and give them reasonable names. (The input file with the model parameters is also included here.) To get started, we suggest to keep the names as they are in this file.
  6. mod****.dat -- 10 files containing the Geneva evolutionary models for standard ("c") and enhanced ("e") mass-loss rates. The chemical composition is 2x solar (040), solar (020), 0.4x solar (008), 0.2x solar (004), and 0.05x solar (001).
  7. lcb97_***.flu -- 5 files containing the model atmospheres of Lejeune et al. They match the metallicities of the evolutionary tracks. Note that some models were interpolated from the original Lejeune set since the required metallicities were not available.
  8. wr_beta*.fluxes -- 2 files with the WR model atmospheres of Schmutz et al. (1992).
  9. sp.dat -- IUE spectral library of O, B, and WR stars used in the subroutine linesyn. This library is also available (in a more readable form) via the CD accompanying the article in PASP, 108, 996 (1996), or from our web page.
  10. sp_low.dat -- FOS and STIS spectral library of LMC/SMC O stars used in the subroutine linesyn. The structure is identical to that of sp.dat. All stars other than O stars are the same as in sp.dat. (Leitherer et al. 2001; ApJ, 550, in press.)
  11. copernicus.dat -- libary of Copernicus spectra around O VI.
  12. schkal.dat -- spectral-type calibration of Schmidt-Kaler (1982). The table simply contains a list of log L (in solar luminosities) and log Teff (in K). Each line corresponds to a certain spectral type.
  13. irfeatures.dat -- contains data for the near-IR CO features at 1.62 and 2.29 microns, and the silicon feature at 1.59 microns from Origlia, Moorwood, and Oliva (1993) A&A, 280, 536.
  14. galaxy.input -- this is the input file specifying the model parameters. It is explained in more detail below.
  15. standard.* -- results of a standard model run. These files are obtained by using the parameters in the galaxy.input file. They can be used for test runs when implementing the code.

How to run the code
Get organized first.

The input
Once all the files are in place and the declarations are complete, the input parameters need to be specified. If this is your first attempt, we suggest to leave the parameters as they are. They produce reasonable results and should give you a first impression of what is in store. Once you have gained more experience and have become more adventurous, you can modify the parameters to suit your needs. These are the parameters to play with:

The output

  1. Computation of the number of ionizing photons. (7) must be set to "yes" since the spectrum below 912 A is needed. Output is the number of ionizing photons in the HI, HeI, and HeII continuum, their fractions relative to the total luminosity, and the total luminosity.
  2. Calculation of the supernova rate and the mechanical luminosities. It requires (4) to obtain the stellar wind luminosities. Otherwise it is independent of other subroutines.
  3. HRD with a few evolutionary tracks. This is mostly useful for test purposes. This part is independent of all other subroutines and can be turned on/off without doing any harm. The HRD cannot be produced in Isochrone Synthesis mode.
  4. Mechanical luminosity and related quantities due to winds. (No supernovae!) It does not depend on any other subroutine since no information on the energy distribution is needed.
  5. Two output files containing the stellar spectral types during each time step and the relative numbers of WR stars. The spectral types follow the scheme by Schmidt-Kaler, oversampled by a factor of 2. For instance, there are 18 entries for spectral type B. They are the number of stars for types B0, B0.5, B1,...B9.5 (total of 18). Schmidt-Kaler's table has B0, B1,....B9 (total of 9). The spectral types are printed out only every TDEL. Otherwise it is too bulky.
  6. The mass in individual elements released via stellar winds and supernovae. No other subroutines are needed. The supernova yields for type II supernovae are taken into account.
  7. The spectrum of the stellar population for each time step. The columns are time, wavelength, stellar+nebular, stellar only, and nebular only fluxes. (1) is needed in order to calculate the nebular continuum.
  8. The ultraviolet line spectrum at 0.75 A resolution from 1200 to 1600 A (LMC/SMC library) or to 1800 A (Milky Way library). The subroutine needs (7) to compute the stellar continuum and (1) for the nebular continuum. If (1) is turned off, the nebular contribution can not be added (it is often small, though). The columns have time, wavelength, absolute luminosity, and rectified (continuum=1) luminosity.
  9. Calculation of colors and magnitudes. The subroutine needs (7) to compute the stellar continuum and (1) for the nebular continuum. If (1) is turned off, the nebular contribution can not be added and the computed colors are for stars only (this may sometimes be desirable). The filter system is defined in the code.
  10. Calculation of the strengths of H_alpha, H_beta, Pa_beta, and Br_gamma. For each line we give the continuum luminosity, the line luminosity, and the equivalent width (everything logarithmic). The subroutine needs (7) to compute the stellar continuum and (1) for the nebular continuum. If (1) is turned off, the nebular contribution can not be added.
  11. Calculations of the strengths of various IR spectral features. First is the CO index as computed by Doyon et al. (1994, ApJ, 421, 101). (Please note that this calculation has no metallicity dependence. A later version of this routine will compute the CO index using the model atmospheres themselves and give metallicity-dependent results.) Next are two computations of the CaII IR triplet using the relations of Diaz et al. (1989, MNRAS, 239, 325). The relations from Diaz et al. have no temperature dependence; the first calculation has the feature present in stars of all temperatures; the second has the index set to zero strength for stars with T>7200K (spectral type A or earlier). Next come the 1.62 and 2.29 micron CO features, and the 1.59 micron Si feature, which were modelled for individual stars by Origlia et al. (1993, A&A, 280, 536.) The indices can be computed for solar [Si/Fe] and [C/Fe], or a model with enhanced [Si/Fe] and depleted [C/Fe] (as for young systems enriched primarily by Type II SNe), and for stellar atmospheric microturbulent velocities (MTVs) of 1-6 km/s. (Note that the changes to the abundance ratios and MTVs are self-contained in this routine and have no effect upon the other outputs, e.g., colors, of the code.)
  12. This subroutine is equivalent to (8), but it computes the spectral region around the O VI doublet.
  13. This subroutine is still under construction. Eventually it will compute the stellar absorption spectrum of the higher Balmer lines. Stay tuned!
  14. Calculation of the most important WR emission lines using the line luminosities of Schaerer & Vacca (1998, ApJ, 497, 658). These are only those lines originating in WR winds --- not the nebular lines in the HII region. Quantities given are the line fluxes and the equivalent widths. The subroutine needs (7) to compute the stellar continuum and (1) for the nebular continuum. If (1) is turned off, the nebular contribution can not be added.