1,534 research outputs found
Stark Broadening of Carbon and Oxygen Lines in Hot DQ White Dwarf Stars: Recent Results and Applications
White dwarf stars are traditionally found to have surface compositions made
primarily of hydrogen or helium. However, a new family has recently been
uncovered, the so-called Hot DQ white dwarfs, which have surface compositions
dominated by carbon and oxygen with little or no trace of hydrogen and helium
(Dufour et al. 2007, 2008, 2010). Deriving precise atmospheric parameters for
these objects (such as the effective temperature and the surface gravity)
requires detailed modeling of spectral line profiles. Stark broadening
parameters are of crucial importance in that context. We present preliminary
results from our new generation of model atmosphere including the latest Stark
broadening calculations for CII lines and discuss the implications as well as
future work that remains to be done.Comment: 6 pages, 1 figure, to appear in Baltic Astronom
Stark broadening of B IV spectral lines
Stark broadening parameters for 157 multiplets of helium like boron (B IV)
have been calculated using the impact semiclassical perturbation formalism.
Obtained results have been used to investigate the regularities within spectral
series. An example of the influence of Stark broadening on B IV lines in DO
white dwarfs is given.Comment: 6 pages, 2 figure
Stark broadening of B IV lines for astrophysical and laboratory plasma research
Stark broadening parameters for 36 multiplets of B IV have been calculated
using the semi-classical perturbation formalism. Obtained results have been
used to investigate the regularities within spectral series and temperature
dependence.Comment: 8 pages, 6 figures, 1 table, in press in Advances in Space Researc
Magnetic Field-Vector Measurements in Quiescent Prominences via the Hanle Effect: Analysis of Prominences Observed at Pic-Du-Midi and at Sacramento Peak
The Hanle effect method for magnetic field vector diagnostics has now provided results on the magnetic field strength and direction in quiescent prominences, from linear polarization measurements in the He I E sub 3 line, performed at the Pic-du-Midi and at Sacramento Peak. However, there is an inescapable ambiguity in the field vector determination: each polarization measurement provides two field vector solutions symmetrical with respect to the line-of-sight. A statistical analysis capable of solving this ambiguity was applied to the large sample of prominences observed at the Pic-du-Midi (Leroy, et al., 1984); the same method of analysis applied to the prominences observed at Sacramento Peak (Athay, et al., 1983) provides results in agreement on the most probable magnetic structure of prominences; these results are detailed. The statistical results were confirmed on favorable individual cases: for 15 prominences observed at Pic-du-Midi, the two-field vectors are pointing on the same side of the prominence, and the alpha angles are large enough with respect to the measurements and interpretation inaccuracies, so that the field polarity is derived without any ambiguity
On the influence of Stark broadening on Si I lines in stellar atmospheres
We study the influence of Stark broadening and stratification effects on Si\i
lines in the rapidly oscillating (roAp) star 10 Aql, where the Si\i 6142.48 \AA
and 6155.13 \AA lines are asymmetrical and shifted. First we have calculated
Stark broadening parameters using the semiclassical perturbation method for
three Si\i lines: 5950.2 \AA, 6142.48 \AA and 6155.13 \AA. We revised the
synthetic sp$ calculation code taking into account both Stark width and shift
for these lines. From the comparison of our calculations with the observations
we found that Stark broadening + the stratification effect can explain
asymmetry of the Si\i 6142.48 \AA and 6155.13 \AA lines in the atmospere of
roAp star 10 Aql.Comment: Accepted to A&
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