Issue |
A&A
Volume 465, Number 2, April II 2007
|
|
---|---|---|
Page(s) | 651 - 665 | |
Section | Atomic, molecular, and nuclear data | |
DOI | https://doi.org/10.1051/0004-6361:20066022 | |
Published online | 22 January 2007 |
Semi-classical Stark broadening calculations of HeI lines in a non-ideal plasma
1
Institut Préparatoire aux Études d'Ingénieur El Manar, Campus Universitaire, BP No 244 Manar II, 2092 Tunis, Tunisia
2
Laboratoire d'Étude du Rayonnement et de la Matière en Astrophysique, UMR CNRS 8112-LERMA, Observatoire de Paris, Section de Meudon, 92195 Meudon Cedex, France e-mail: Sylvie.Sahal-Brechot@obspm.fr
3
Groupe de Recherche en Physique Atomique et Astrophysique, Institut National des Sciences Appliquées et de Technologie, Centre Urbain Nord, BP No 676, 1080 Tunis Cedex, Tunisia
Received:
12
July
2006
Accepted:
11
December
2006
New semi-classical collision functions are used to
compute the inelastic contribution to the impact electronic total
width, by considering three interaction potentials (Coulomb Debye,
Cut-off, and Ion Sphere). Numerical results are calculated for the
neutral helium 6678 Å () and 5876 Å (
)
visible lines. The lines corresponding to
these transitions are isolated, and the plasma is weakly non-ideal
for all temperatures and electronic densities of interest. For
electronic collisions, semi-classical perturbation theory is
sufficient and the impact approximation is well satisfied. The ion
effects can be treated within the quasistatic approximation, and
the quasistatic ionic contribution is dominated by the
polarization (or quadratic)
-interaction. To consider
both the electron and the ion effects, the microfield
distributions and the complete reduced Stark profile of isolated
line are calculated using different methods. The computed total
widths corresponding to the three interaction potentials are
compared to the available experimental widths and then
approximated by appropriate formulae. The data we obtained provide
an opportunity to test various approximations included in the
semi-classical perturbation formalism. They are also of interest
for stellar spectroscopic diagnosis in dense atmospheres (white
dwarfs for instance).
Key words: atomic data / line: profiles / atomic processes
© ESO, 2007
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