A set of tables of the Stark width of the first three lines of Lyman and Balmer series of hydrogen, useful for plasma diagnosis purposes, is presented in this work. These tables have been obtained by means of a fully recognized computer simulation technique. Computer experiments have been carried out for density values between and . Simulation temperatures range from 2245 K to 224 856 K. Ion dynamics effects are taken into account in a natural way and the most significative gas mixtures have been covered in the simulations, carried out at the reduced mass of the emitter - perturber pair , 0.6, 0.8, 0.9, 1.0, 1.25, 1.5, 1.75 and 2.0. A detailed discussion of the influence of the relevant plasma parameters on the characteristics of the profiles is also included. The results show an excellent agreement with up-to-date experimental results and confirm these kind of profile calculation techniques as now the most accurate.

https://iopscience.iop.org/article/10.1088/0953-4075/29/20/029/pdf

New plasma diagnosis tables of hydrogen Stark broadening including ion dynamics

High-precision spectroscopy of large stellar samples plays a crucial role for several topical issues in astrophysics. Examples include studying the chemical structure and evolution of the Milky Way Galaxy, tracing the origin of chemical elements, and characterizing planetary host stars. Data are accumulating from instruments that obtain high-quality spectra of stars in the ultraviolet, optical and infrared wavelength regions on a routine basis. These instruments are located at ground-based 2-10 m class telescopes around the world, in addition to the spectrographs with unique capabilities available at the Hubble Space Telescope. The interpretation of these spectra requires high-quality transition data for numerous species, in particular neutral and singly ionized atoms, and di-or triatomic molecules. We rely heavily on the continuous efforts of laboratory astrophysics groups that produce and improve the relevant experimental and theoretical atomic and molecular data. The compilation of the best available data is facilitated by databases and electronic infrastructures such as the NIST Atomic Spectra Database, the VALD database, or the Virtual Atomic and Molecular Data Centre. We illustrate the current status of atomic data for optical stellar spectra with the example of the Gaia-ESO Public Spectroscopic Survey. Data sources for 35 chemical elements were reviewed in an effort to construct a line list for a homogeneous abundance analysis of up to 10(5) stars.

https://iopscience.iop.org/article/10.1088/0031-8949/90/5/054010/pdf

Atomic and Molecular Data for Optical Stellar Spectroscopy

After noting that a generation of large optical telescopes is under construction and commenting briefly on the problems in stellar spectroscopy that these telescopes will address, the review focuses on the need for more complete information on the interactions between H atoms and the atoms whose spectral lines are to be investigated in stellar spectra. The H-atom collisions may determine the atomic lines' widths and may influence the excitation and ionization of the atom.

Quantitative stellar spectroscopy with large optical telescopes

The measurement of stellar properties such as chemical compositions, masses and ages, through stellar spectra, is a fundamental problem in astrophysics. Progress in the understanding, calculation and measurement of atomic properties and processes relevant to the high-accuracy analysis of F-, G-, and K-type stellar spectra is reviewed, with particular emphasis on abundance analysis. This includes fundamental atomic data such as energy levels, wavelengths, and transition probabilities, as well as processes of photoionisation, collisional broadening and inelastic collisions. A recurring theme throughout the review is the interplay between theoretical atomic physics, laboratory measurements, and astrophysical modelling, all of which contribute to our understanding of atoms and atomic processes, as well as to modelling stellar spectra.

Accurate abundance analysis of late-type stars: advances in atomic physics

The central structure of the Stark-broadened Balmer line Hbeta has been analysed in the plasma produced behind the reflected shock in a combustion-driven shock tube of internal diameter 10 cm. The incident shock is propagated at a Mach number typically of M=8 in a mixture of 0.5% H2(D2), 80% Ne, 20% He (Ar) at an initial pressure of 10 Torr creating in the reflected-shock region temperatures close to 104K and electron number densities 1016<Ne<1017. Measuring times are 150 mu s. The variation of centre dip with reduced mass which has now been measured in two widely differing plasma sources strongly suggests that the discrepancy between theory and experiment for the central structure of Hbeta is due to ion dynamical effects.

Measurement of the ion-mass effect on the central structure of Hβ in a plasma produced by a combustion-driven shock tube

The broadening and shift parameters of the sodium D lines perturbed by atomic hydrogen have been measured in the plasma produced behind the reflected shock in a combustion-driven shock tube. The incident shock wave is propagated at a Mach number typically of M=11 in hydrogen with an admixture of Ar (10 to 40% in volume) at an initial pressure of a few Torr. The conditions created in the reflected shock region are the following: temperatures in the range of 4500 to 600K, molecular hydrogen dissociation from 90 to 99% and atomic hydrogen number densities 1017<NH<1019 cm-3. The electron number density is negligible. The line profiles are recorded with an intensified Reticon photodiode array coupled to a high-resolution spectrograph. The instrumental width is about 125 mAA. By varying the gas mixture composition, the initial pressure and the shock strength, and assuming the validity of the impact approximation, the damping constants of the three species Ar, H, H2 can be separated. The values obtained for Ar and H2 agree with previous measurements made in different experimental conditions; for atomic hydrogen, our new, more accurate values differ significantly from the available theoretical results.

J L Chotin

Papers

Measurement of the ion-mass effect on the central structure of Hβ in a plasma produced by a combustion-driven shock tube

Broadening and shift parameters of the sodium D lines perturbed by atomic hydrogen