This work communicates a review on Balmer series hydrogen beta line measurements and applications for analysis of white dwarf stars. Laser-induced plasma investigations explore electron density and temperature ranges comparable to white dwarf star signatures such as Sirius B, the companion to the brightest star observable from the earth. Spectral line shape characteristics of the hydrogen beta line include width, peak separation, and central dip-shift, thereby providing three indicators for electron density measurements. The hydrogen alpha line shows two primary line-profile parameters for electron density determination, namely, width and shift. Both Boltzmann plot and line-to-continuum ratios yield temperature. The line-shifts recorded with temporally-and spatially-resolved optical emission spectroscopy of hydrogen plasma in laboratory settings can be larger than gravitational redshifts that occur in absorption spectra from radiating white dwarfs. Published astrophysical spectra display significantly diminished Stark or pressure broadening contributions to red-shifted atomic lines. Gravitational redshifts allow one to assess the ratio of mass and radius of these stars, and, subsequently, the mass from cooling models.

This work communicates a review on Balmer series hydrogen beta line measurements and applications for analysis of white dwarf stars. Laser-induced plasma investigations explore electron density and temperature ranges comparable to white dwarf star signatures such as Sirius B, the companion to the brightest star observable from the earth. Spectral line shape characteristics of the hydrogen beta line include width, peak separation, and central dip-shift, thereby providing three indicators for electron density measurements. The hydrogen alpha line shows two primary line-profile parameters for electron density determination, namely, width and shift. Both Boltzmann plot and line-to-continuum ratios yield temperature. The line-shifts recorded with temporally- and spatially- resolved optical emission spectroscopy of hydrogen plasma in laboratory settings can be larger than gravitational redshifts that occur in absorption spectra from radiating white dwarfs. Published astrophysical spectra display significantly diminished Stark or pressure broadening contributions to red-shifted atomic lines. Gravitational redshifts allow one to assess the ratio of mass and radius of these stars, and subsequently, the mass from cooling models.

Microplasma is generated in an ultra-high-pure H and N gas mixture with a Nd:YAG laser device that is operated at the fundamental wavelength of 1064 nm. The gas mixture ratio of H and N is 9 to 1 at a pressure of 1.21 ± 0.03 10 Pa inside a chamber. A Czerny-Turner-type spectrometer and an intensified charge-coupled device are utilized for the recording of plasma emission spectra. The line-of-sight measurements are Abel inverted to determine the radial distributions of electron number density and temperature. Recently derived empirical formulas are utilized for the extraction of values for electron density. The Boltzmann plot and line-to-continuum methods are implemented for the diagnostic of electron excitation temperature. The expansion speed of the plasma kernel maximum electron temperature amounts to 1  km/s at a time delay of 300 ns. The microplasma, initiated by focusing 14 ns, 140 mJ pulses, can be described by an isentropic expansion model.

This work elaborates on laboratory measurements of hydrogen Balmer series lines and diatomic molecular species in laser-plasma. Comparisons with astrophysical white dwarf spectra, recorded at various observatories and the Hubble space telescope, point out direct applications of experimental results. The recorded general relativity gravitational- or Einstein-shift of the atomic lines allows one to infer the ratio of mass and radius. The Stark-effect redshifts of hydrogen alpha and hydrogen beta lines investigated with time-resolved emission spectroscopy are usually one order of magnitude larger than the gravitational shift. In view of white dwarf atmospheres dominated by hydrogen and the associated absorption spectra, averaging the laser-induced plasma data reveals spectral line shapes that mask the redshift caused by the Stark effect. The available white dwarf data indicate that the collected radiation propagated through regions of different density in the star’s atmosphere. Diatomic spectra are typically recorded as white dwarfs further progress in their transformation.