2022A&A...657A.121A -
Astronomy and Astrophysics, volume 657A, 121-121 (2022/1-1)
Collisional effects in the blue wing of the Balmer-α line,.
ALLARD N.F., SPIEGELMAN F., KIELKOPF J.F. and BOURDREUX S.
Abstract (from CDS):
In order to investigate the near wing of the Lyman-α line, accurate line profile calculations and molecular data are both required due to the existence of a close line satellite responsible for its asymmetrical shape. Lyman-α lines observed with the Cosmic Origin Spectograph on the Hubble Space Telescope show this peculiarity in the spectra of DBA and DA white dwarf stars. A similar asymmetrical shape in the blue wing can be predicted in the Balmer-α line of H perturbed by He and H atoms. In continuation with a very recent work on the Lyman-α line, where the n = 2 potential energies and transition dipole moments from the ground state were determined, we present new accurate H-He potential energies and electronic transition dipole moments involving the molecular states correlated with H(n = 3)+He and their transition dipole moments with the states correlated with H(n = 2)+He. Those new data and existing molecular data for H(n = 2,3)-H are used to provide a theoretical investigation of the collisional effects in the blue wing of the Balmer-α line of H perturbed by He and H atoms. We note the consequences for the Balmer-α line shape in the physical conditions found in the cool atmosphere of DZA white dwarfs where helium densities may be as high as 1021 cm–3. This study is undertaken with a unified theory of spectral line broadening valid at very high helium densities.
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Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
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References (203 between 1850 and 2024) (Total 203)
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