Graphical User Interfaces for SPECTRUM
Graphical user interfaces using the Tcl/Tk Tool Command Language
and graphical interface have been designed for both SPECTRUM and
BLACKWEL. These GUIs are intended to make using SPECTRUM and
BLACKWEL more easy.
Tcl/Tk GUI for SPECTRUM
The script spectrum_sh.tcl is a Tcl/Tk graphical user interface for
SPECTRUM. It is included in the SPECTRUM releases of versions
2.65 and later. The file spectrum_sh.tcl should be placed in a
directory in your path. I put it in /usr/local/bin. Make
certain that 1) you have Tcl/Tk installed on your computer (it is a
standard feature on most Linux distributions, but may need to be
installed on some UNIX and Linux distributions. It is available
at the Tcl Developer
Xchange. ) and 2) that spectrum_sh.tcl has executable permissions
set.
This shell may be invoked by typing at the prompt:
> spectrum_sh.tcl
The GUI will come up and should look like the figure below:
The buttons on the top row can be used to select the atmosphere model,
the atomic data file (atom.dat), the isotope definition file
(isotope.iso), the spectral line list (luke.lst) and the output
file. The computation parameters are self-explanatory and must be
supplied. The shell enables the user to apply a number of
switches which control the operation of SPECTRUM. Please read the
documentation to understand the meaning of these switches. On the
first row, the default output (Normalized Intensity), absolute flux, or
center of disk switches can be set (corresponding to: no switch, f and
m, respectively). On the second row, the isotope facility may be
turned on (the isotope definition file must have been selected above)
and/or the facility to read ATLAS9 default headers (switch t) can be
selected. If selected, the output spectrum may then be smoothed
using MACTURB (which convolves the spectrum with a macroturbulent
velocity line profile), AVSINI, which rotationally broadens the output
spectrum, and SMOOTH2, which convolves the output spectrum with a
Gaussian function. Please note that for all of the above to work,
the auxiliary programs MACTURB, AVSINI and SMOOTH2 must have been
compiled and placed in the path (/usr/local/bin or some other directory
in your path). To execute, press the Execute button. To see
the progress as SPECTRUM steps through the wavelength region, click the
Progress check box. Pressing Quit will exit the shell.
Please note that this shell is not absolutely foolproof. Please
pay very close attention to the "*"ed boxes - i.e. the isotope box and
the output spacing box for the Smooth option.
Tcl/Tk GUI for BLACKWEL
Before attempting to use this shell, please read over the documentation
for Blackwel. This shell is also included in the 2.65 and later
distributions, and is called blackwell_sh.tcl. It should be
copied to a directory in your path (e.g. /usr/local/bin) and it should
be confirmed that the executable permission has been set. To
invoke this shell, type at the prompt:
> blackwell_sh.tcl
The GUI illustrated below should appear:
To run this shell, you must have installed on your machine the latest
version (4.0 or later) of gnuplot.
To run this shell, select the stellar atmosphere model (67244k2p00.mod
is provided to test this shell with - please use it with the feI.eqw
file also provided), the atomic data file (atom.dat) and an equivalent
width file for a single species (the file feI.eqw is provided).
The equivalent width file contains equivalent widths for lines measured
in an observed stellar spectrum. The stellar atmosphere model
that you use should be appropriate for the star you are studying.
Select a range of microturbulent velocities over which you want
Blackwel to do its computations and then press Execute. For this
set of files, you will get the following graph, courtesy of gnuplot:
Each sloping line in this graph corresponds to a spectral line in the
file feI.eqw. This is a plot of the Microturbulent velocity
against the abundance (in this case) of iron. Notice that
(somewhat ideally!) all of the lines seem to converge at a point in the
plot. This gives the optimal value for the abundance of iron and
the characteristic microturbulent velocity in the atmosphere of the
star under consideration. If you have chosen the temperature and
gravity of the star correctly, you will get nearly the same answer for
Fe II lines. And, for other species, you should get, within the
errors, the same value of the microturbulent velocity. The figure
above is an example of a "Blackwell Diagram", which is a useful tool
for determining microturbulent velocities and abundances in a
consistent way in stellar atmospheres.
Please note that the lines can fail to converge in a Blackwell diagram
if 1) one or more of your lines is in an undetected blend, 2) the gf
values for one or more of your lines are not good, 3) your choice of a
stellar atmosphere to model your star is not good, or 4) your line is
strongly affected by non-LTE effects. You should use a stellar
atmosphere computed with a microturbulent velocity which is as close as
possible to the value indicated by the Blackwell Diagram as possible,
for the sake of consistency. The model atmosphere 67244k2p00.mod
was computed with a microturbulent velocity of 2km/s. Since the
diagram above indicates that the microturbulent velocity is closer to
1.2 km/s, it would be better to select a model computed with a
microturbulent velocity of 1 km/s.
Please note that Blackwell cannot be used with hydrogen or helium lines
(both He I and He II). Ideally, lines used to compute Blackwell
diagrams should be weak to medium strength lines. The cores of
strong lines are often not well computed in the LTE
approximation. A range of line strengths is required in a
Blackwell diagram. The weak lines (which are not strongly
affected by microturbulence) are nearly horizontal in a Blackwell
diagram. Stronger lines have a steeper slope.
Note that blackwell_sh.tcl outputs data you can use to reconstruct the
above graph in individual data files labeled with the wavelength of the
line.
The shell blackwell_sh.tcl can be directed to give the above plot in
postscript format.