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In this paper we emphasize the non-Lorentzian behavior of the Balmer seriesin helium-dominated DBA white dwarf stars for which the decades-old problemexists for the determination of the hydrogen abundance. In a very recent work,we have shown that quasi-molecular line satellites due to H-He and H-Hcollisions are responsible for the asymmetrical shape of the Lyman-alpha linesobserved with the Cosmic Origin Spectrograph (COS) and that a similar asymmetryexists for the Balmer-alpha line profiles. In continuation with very recentwork, where the n=2, 3 potential energies and transition dipole moments fromthe ground state were determined, here, we present accurate H-He potentialenergies and electronic transition dipole moments concerning the molecularstates correlated with H(n=4)+He and their transition dipole moments with thestates correlated with H(n=2)+He. Those new data are used to provide atheoretical investigation of the collisional effects in the blue wing of theBalmer-beta line of H perturbed by He. Because of the general trendcharacterizing the repulsive Sigma states of the potential energies involved inthe Balmer series, the amplitude in the core of the line is decreasing veryfast with the order of the series when the helium density gets as large as10^21 cm^-3. This study is undertaken by applying a unified theory of spectralline broadening that is valid at very high helium densities found in DZA whitedwarf stars.  The treatment includes collision-induced (CI) line satellites due toasymptotically forbidden transitions, and it explains the asymmetry observed intheir spectra.

Collision-induced satellite in the blue wing of the Balmer-beta line and consequences on the Balmer series