POSTER PAPER 11.08
Improved Line Ratio Calculations for He-like Ions
R. Mewe, D. Porquet, A.J.J. Raassen, J.S. Kaastra, J. Dubau, J. -U. Ness
Institute: Space Research Organization Netherlands (SRON), Utrecht
Institute: CEA/DSM/DAPNIA, Gif sur Yvette Cedex
Institute: Astronomical Institute, Amsterdam
Institute: LSAI, U.M.R. 8624, CNRS, Orsay Cedex
Institute: Universitat Hamburg, Hamburger Sternwarte
Contact Email: R.Mewe@sron.nl
Abstract:
Helium-like density and temperature diagnostics, since more than three decades applied to the Sun, have now become a powerful tool in the analysis of the high-resolution Chandra
and XMM-Newton X-ray spectra. Therefore, we
have revisited the calculation of the ratios R=f/i and G=(f+i)/r
of the resonance r (1s2 1S0 -- 1s2p1P1),
intercombination i (1s2 1S0 -- 1s2p3P2,1), and
forbidden f (1s2 1S0 -- 1s2s3S1) ``triplet'' lines
of the He-like ions C V, N VI, O VII, Ne IX, Mg XI,
and Si XIII, taking into account all relevant processes and improved atomic data.
The first calculations have been done for optically thin plasmas in collisional ionization equilibrium
(e.g., stellar coronae).
The influence of an external radiation field on the depopulation of the upper level of
f is considered which can be important for hot OB or F stars (e.g.,
Zeta Puppis, Procyon, and Algol).
In preparation are updated calculations for photo-ionized and hybrid plasmas (e.g.,
warm absorber in AGNs), and for
transient ionization plasmas (young SNRs).
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Manuscript submitted: 2001-Aug-27
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.