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Bull. Astron. Soc. India (1999) xx,
PINTofALE: Package for the Interactive Analysis of Line Emission
V.Kashyap & J.J.Drake
Center for Astrophysics, Cambridge, MA 02138, USA
Abstract. PINTofALE was developed to analyze spectroscopic data from coro­
nal sources in the 1­1500 š A range. It is based on a modular set of IDL tools that
interact with an atomic database and with observational data. The tools allow
us to easily identify spectral lines, measure fluxes, and carry out more detailed
modeling. The package has been extended to handle analysis of high­resolution
X­ray spectra that will be obtained with the Chandra X­Ray Observatory.
Key words: X­rays, X­ray Spectroscopy, Stellar Coronae, Analysis Methods
1. Introduction
The scientist wishing to analyse EUV and X­ray spectra has a choice of how to proceed:
use an existing ``black box'' compilation of atomic data hard­coded into a program with a
fixed functional capability (e.g. the XSPEC [Arnaud 1996] and SPEX [Kaastra et al. 1996]
packages); or gather the atomic data oneself and perform analyses ``by hand.'' While
very good in their own right, the former type of packages were developed with statistical
fitting of spectral models to low resolution X­ray spectra in mind. For spectra of higher
resolution (e.g. EUVE, Chandra, and XMM), such approaches are of limited use and can
even be misleading owing to incompleteness and errors in the underlying atomic data (e.g.
Drake 1996). More discerning analyses involving selective use of well­measured spectral
lines and well­known atomic data are generally needed to derive reliable constraints on
source emission models. However, measuring line emission/absorption profiles, identi­
fying the lines in complex spectra (e.g., from stellar coronal sources), deblending the
contributions from different species, correctly accounting for the temperature and den­
sity responses of the various lines, etc. can be a hard task. We have therefore developed
an analysis system that is much more flexible for analysing high resolution spectra than
existing packages and that offers completely transparent access to atomic data. We
describe its structure and briefly describe its status in the following section.

V.Kashyap & J.J.Drake
2. Summary
Here we report on an IDL based modular software package for interactive analysis
of line emission (PINTofALE) that focuses on the analysis of high­resolution spectra of
collision­dominated, optically­thin, thermal bremsstrahlung emission sources, such as
stellar coronae. In general, the emission in the wavelength range [–; – + \Delta–] includes
contributions from atomic line transitions (¸ A(Z)
R
\DeltaT ul
\Phi(T ; Z; z)G ul (T )N 2
e (T )dV (T );
where \Phi(T ; Z; z) are the ion populations of ionic species Z +z , G ul (T ) are the atomic
``contribution'' functions for the transition u ! l, A(Z) are the abundances, and N e are
the electron densities in the emission volume dV ), and continuum emission as a result of
free­free (Bremsstrahlung), free­bound, and two­photon processes.
None of the existing compilations of atomic line transitions in the EUV and X­ray
region such as CHIANTI (Dere et al. 1996), SPEX (Kaastra et al. 1996), and RS (Raymond
& Smith 1977) are complete. We therefore re­cast these databases into a uniform format
that allows us to pick transparently the appropriate line transitions from any of the
supported databases, and to add new atomic data as desired. We also separate out ion
populations from the direct atomic contribution function, and are thus able to consider
different versions of ion balance calculations (e.g. Arnaud & Rothenflug 1986, Arnaud &
Raymond 1992), as well as allow for calculation of line fluxes in the absence of ionization
equilibrium. Abundances and emission measure distributions may also be separately
defined. We compute continua using the algorithms described by Mewe et al. (1986).
The results of the line identification process are stored centrally in a data structure
that is flexible enough to include both observed and predicted line strengths, allow mul­
tiple IDs for a blended line, allow identifications with multiple grating orders, etc. These
results are then used to perform further analysis, such as determining the Solar coronal
Differential Emission Measure (Kashyap & Drake 1998).
This package has been used to analyze solar spectral data (Kashyap & Drake 1998),
EUVE data of ¸ Boo A (Drake et al. 1999) and other stars (Kashyap et al. 1997). In
the future, we plan to include the APEC atomic line database (Brickhouse et al. 1999, in
preparation) when it becomes available, and provide support for the ``pseudo­continuum''
of the vast number of faint lines. We also plan to merge PINTofALE into the Chandra
Data Analaysis system.
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