How to run a model with Starburst99
First you need to specify your input parameters. This is done from the
input page. There are quite a few parameters to play with, all of which are
explained below. If you are not sure about an input parameter, start out with
the default value.
MODEL DESIGNATION: --- any identifier you want to assign to the model. You will find
it in the header of each output file.
CONTINUOUS STAR FORMATION OR FIXED MASS : -- if this is a negative integer, star formation is instantaneous,
otherwise it is continuous.
TOTAL STELLAR MASS [106 SOLAR MASSES] IF 'FIXED MASS' IS CHOSEN:-- this is the total stellar mass (spread out between the upper and lower
cut-off masses). It is only used if an instantaneous burst is specified.
SFR [SOLAR MASSES PER YEAR] IF 'CONT. SF' IS CHOSEN: -- the star formation rate (only used for a continuous rate). The total
accumulated mass is spread out between the upper and lower
IMF EXPONENT (2.35 = SALPETER): -- IMF exponent. A power law is assumed.
UPPER MASS LIMIT FOR IMF [SOLAR MASSES]: -- upper mass limit for the IMF.
LOWER MASS LIMIT FOR IMF [SOLAR MASSES]: -- lower mass limit for the IMF.
SUPERNOVA CUT-OFF MASS [SOLAR MASSES]: -- stars with ZAMS masses of 8 M and higher form supernovae. This is the
suggested standard value but can be modified if desired.
BLACK HOLE CUT-OFF MASS [SOLAR MASSES]: -- stars with ZAMS masses of 120 M and lower form supernovae. An
alternative scenario would be to let stars above a certain threshold
form a black hole. For instance, BHCUT=40 results in SNe only from the
mass range 40 to 8 M.
METALLICITY + TRACKS: -- this selects the metalicity and evolutionary tracks to be used.
Standard and high mass loss tracks can be used.
WIND MODEL (MAEDER; EMP.; THEOR.; ELSON): -- this selects the wind model to be used for the calculation of the
wind power. The four models are discussed in ApJ, 401, 498 (1992). "THEOR."
is the suggested default parameter.
INITIAL TIME [1.E6 YEARS]: -- the epoch of the onset of the star formation. In almost all cases you
want this to be close to 0. It should not be exactly 0 for numerical
reasons. 0.01 (i.e. 10e4 yr) is a good number.
TIME STEP [1.e6 YEARS]: -- this is the timestep used for the calculations. It is a very important
parameter. On the one hand, the computing time scales with STEP so
you want to avoid too high resolution, but on the other, short
evolutionary phases can be missed. 0.1 (i.e. 10e5 yr) is a good
value. A larger time step is suggested for tests --- but be aware that WR
or RSG numbers are no longer properly calculated for too large STEPs!
LAST GRID POINT [1.e6 YEARS]: -- the oldest age of the model.
SMALL OR LARGE MASS GRID;
ISOCHRONE ON LARGE GRID OR FULL ISOCHRONE : -- these are four options for the interpolation in mass. They are explained
in the code. Shortly: "SMALL" -- evolutionary synthesis with a mass
resolution of 5 M (only recommended for tests); "LARGE" -- same as 0, but with
a resolution of 1 M. This method was used in our previously published
papers; "ISOCHRONE/LARGE" -- isochrone synthesis with a fixed mass resolution of 1 M;
"FULL ISOCHRONE" -- isochrone synthesis with a variable mass grid. This is the fanciest
LMIN, LMAX : -- LMIN and LMAX are the indices of the evolutionary tracks, sorted by mass.
Normally you do not want to mess with the variable and leave it at 0.
However, if you want to track down some peculiarity of the output, you
may want to compute the parameters for only one track. For instance,
specifying 21,21 indicates that only a 100 M star should be used, and
everything else is suppressed. The cross-ID's between index and mass
are at the bottom of the input file which comes as part of the source code package. The example here refers to a large mass grid or
isochrone on large grid. For a small mass grid, you would have chosen 5,5. This does not appy to the full isochrone model
since the mass grid is variable. If "full isochrone" is selected, LMIN and LMAX are not used.
TIME STEP FOR PRINT OUT OF SYNTH.SPECTRUM AND LINE [1.e6YR]: -- the file containing the output spectrum can be pretty big. This
parameter controls the time step to print out the spectrum. This is
independent of the time resolution -- only the print out is affected!
1 Myr is usually a good value but if you compute the starburst up to
100 Myr, you may prefer TDEL=5 Myr to save disk
ATMOSPHERE FOR SYNTHETIC SPECTRUM: PLANCK, KURUCZ, KURUCZ-SCHMUTZ -- this is the choice of the model atmosphere. "PLANCK" is a bare-bone version with
black bodies, good only for tests. "KURUCZ" uses the Kurucz models as compiled
by Lejeune for all stars. "KURUCZ-SCHMUTZ" uses Lejeune for stars with plane-parallel
atmospheres and Schmutz with stars with strong winds. "KURUCZ-SCHMUTZ" is the recommended
METALLICITY OF THE UV LINE SPECTRUM: (1=SOLAR, 2=LMC/SMC) -- a
switch for the choice of the UV spectral library. This is independent
of the metallicity of the tracks/atmospheres. Normally one would use
ILINE=1 with IZ=14/24 and ILINE=2 with IZ=12/22.
RSG FEATURE: MICROTURB. VEL (1-6), SOL/NON-SOL ABUND -- atmospheric parameters used for the spectral features in the near-IR.
Detailed explanations are in the sp-feature subroutine. Defaults are microturbulent velocities of 3 km/sec and solar abundance
ratios for alpha-element/Fe
These are options to generate various outputs. We recommend to select all files, unless you are very familiar with the code. Some of the subroutines
are interrelated. If you choose such a subroutine but not the other, required
one, a warning will be issued. The 14 output flags are explained below.
Once the run is finished, you will be notified by e-mail. If everything went
well, you should find the output files in the output directory. The e-mail
gives you all the information you need to locate the files and the retrieve
them. If you have set all output flags to "yes", you will find 16 files: 15
files with model results (note that (5) generates 2 files, therefore the 14
flags produce 15 files), and one output file which lists the model parameters
which were used. The data files are:
- 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.
Default filename: quanta
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.
Default filename: snr
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.
Default filename: hrd
Mechanical luminosity and related quantities due to winds and supernovae.
It does not depend on any other subroutine since no information on the
energy distribution is needed.
Default filename: power
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.
Default filenames: sp1,sp2
The mass in individual elements released via stellar winds and supernovae.
No other subroutines are needed. Note that the elements are simply assumed
to be ejected during a SN event. No nucleo-processing is included!
Default filename: yield
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.
Default filename: spectrum
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.
Default filename: line
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.
Default filename: color
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.
Default filename: width
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, 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
modeled 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 are
self-contained in this routine and have no effect upon the other
outputs, e.g., colors, of the code.)
Default filename: feature
This subroutine is equivalent to (8), but it computes the spectral region
around the O VI doublet.
Default filename: ovi
This subroutine is still under construction. Eventually it will compute
the stellar absorption spectrum of the higher Balmer lines. Stay tuned!
Default filename: balmer
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.
Default filename: wr
How to interpret the file time-used
The logfile "time-used" gives statistics on cpu and elapsed time, and it reports
warnings and anomalies or errors that may have occurred during the run.
If you see "CANNOT COMPUTE....." you have specified to skip a particular
output which was otherwise needed as input for another subroutine which
specified to compute. For instance, you may intentionally omit the nebular
continuum (quanta) in order to compute a purely stellar continuum. But then
you would not be able to compute equivalent widths (width) since the number
of ionizing photons is needed for the emission line fluxes. When in doubt,
compute all the output files. This will work.
"IEEE floating point exception flags" may also be ignored.