XTGRID – Stellar Spectroscopic Diagnostics
Version 32
XTGRID is a multi-purpose, multi-wavelength
spectral fitting procedure for TLUSTY/SYNSPEC. The idea of a new
steepest-descent χ2 minimization program came up in Ondrejov in
the fall of 2010. After having done spectral analysis for novae in the
X-rays by interpolating in a precalculated grid, a new, more flexible and
reliable procedure became necessary. A proper χ2
minimization spectral analysis of classical novae is
difficult with a precalculated grid due to the many free
parameters these spectra require. Developing a new method for something
we don't really know is, at least, risky. Fortunately, a large set
of subdwarf data were available in our group at that time. These evolved
stars were not only good for developing the method, they opened a way
for testing and validating the new and quite general spectral fitting interface.
In its first
application H/He/CNO model atmospheres and binary spectral decomposition
were included in the modeling of ~170 hot subdwarfs
from the GALEX survey.
The program is under continuous developement
to accomplish its original task and fit supersoft X-ray sources. Among many
necessary improvements an appropriate ISM absorption model is needed in the
fitting algorithm, currently the standalone XSPEC
ISM model is under consideration.
The code has a potential to do
direct exoplanet spectroscopy with COOLTLUSTY, a
field what needs to be explored in the future.
XTGRID is offered to the community through the
Astroserver.org framework.
For a review on the most recent version of the code, see:
