Processes of (n – n )-mixing in collisions of Rydberg H ∗ (n) atoms with H (1s) in the Solar atmosphere (original) (raw)
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Journal of Physics: Conference Series, 2019
Non-LTE modelling requires accurate atomic data e.g. collisional excitation and ionization cross-sections and rate coefficients. In order to improve the modeling of the solar photosphere, as well as to model atmospheres of other similar and cooler stars where the main constituent is also hydrogen, it is necessary to take into account the influence of all the relevant collisional processes on the excited-atom populations in weakly ionized hydrogen plasmas. In this context we present the data needed for the inclusion of the specific atomic collisional processes in the investigation of the optical and kinetic properties of weakly ionized stellar atmospheres layers. The ionization processes in collisions of excited hydrogen atoms with atoms in ground states were considered for the principal quantum numbers 2 ≤ n ≤ 20 and temperatures 4000 K ≤ T ≤ 20000 K.
The Collisional Atomic Processes of Rydberg Hydrogen and Helium Atoms: Astrophysical Relevance
Elementary processes in astrophysical environments traditionally attract researchers' attention. We present the data needed for the inclusion of the specific atomic collisional processes in the investigation of the optical and kinetic properties of weakly ionized stellar atmosphere layers. The first type of processes are collisional ionisation (chemi-ionization) processes, and the second ones are excitation and de-excitation (i.e., (n − n)-mixing processes). We give the rate coefficients of the aforementioned processes for the conditions that exist in the solar photosphere, the atmosphere of DB white dwarfs, M-type red dwarfs, etc.
Monthly Notices of the Royal Astronomical Society, 2016
In this paper, the rate coefficients of the chemi-ionization processes in H(1s) + H*(n, l) and He(1s 2) + He * (n, l) collisions (where the principal quantum number n 1) are determined for the first time, taking into account the influence of the corresponding (n − n)-mixing processes. It is demonstrated that the inclusion of (n − n) mixing in the calculation influences the values of chemi-ionization rate coefficients significantly, particularly in the lower part of the block of Rydberg states. The interpretation of this influence is based on two existing methods of describing inelastic processes in symmetrical atom-Rydberg-atom collisions. The calculations of the chemi-ionization rate coefficients are performed for the temperature region that is characteristic of solar and DB white-dwarf atmospheres.
Astronomy and Astrophysics, 2003
We study the influence of a group of chemi-ionization and chemi-recombination processes on the populations of higher states of hydrogen in the layers of a stellar atmosphere. The group of processes includes ionization: H * (n) + H(1s) =⇒ H + 2 +e , H * (n)+H(1s) =⇒ H(1s)+H + +e, and inverse recombination: , where H * (n) is the hydrogen atom in a state with the principal quantum number n 1, and H + 2 is the hydrogen molecular ion in a weakly bound rho-vibrational state of the ground state. These processes have been treated within the framework of the semi-classical approximation, developed in several previous papers, and have been included in the general stellar atmosphere code . We present results for an M dwarf atmosphere with T eff = 3800 K and find that the inclusion of chemi-ionization and chemi-recombination processes is significant in the low temperature parts of the atmosphere.
CHEMI-IONIZATION IN SOLAR PHOTOSPHERE: INFLUENCE ON THE HYDROGEN ATOM EXCITED STATES POPULATION
The Astrophysical Journal Supplement Series, 2011
In this paper, the influence of chemi-ionization processes in H * (n ≥ 2)+H(1s) collisions, as well as the influence of inverse chemi-recombination processes on hydrogen atom excited-state populations in solar photosphere, are compared with the influence of concurrent electron-atom and electron-ion ionization and recombination processes. It has been found that the considered chemiionization/recombination processes dominate over the relevant concurrent processes in almost the whole solar photosphere. Thus, it is shown that these processes and their importance for the non-LTE modeling of the solar atmosphere should be investigated further.
In this paper we have presented some of our preliminary results illustrating the influence of a group of symmetrical chemical ionization and chemical recombination processes on the populations of hydrogen-atom Rydberg states in low-temperature layers of stellar photospheres and a part of chromospheres. These processes are H Ã (n) þ H(1s) ! H þ 2 þ e=H(1s) þ H þ e and H 2 þ e ! H (n) þ H(1s), H(1s) þ H þ e ! H (n) þ H(1s), where H Ã (n) is the hydrogen atom in a Rydberg state with the principal quantum number n ) 1, and H þ 2 is the hydrogen molecular ion in a weakly bound rovibrational state. The mentioned processes have been considered within the framework of the semiclassical approximation, developed in several previous papers. Their influence on the populations of hydrogen-atom Rydberg states has been investigated by direct inclusion in a computer code for stellar atmosphere modelling. Here we present some of our preliminary results for the M dwarf atmospheres. Our results show that the influence of these processes is significant for the considered stellar atmospheres, so that they should be taken into account for their modelling.
Proceedings of The International Astronomical Union, 2003
Results of our investigations of the influence of radiation, chemi-ionization and chemi-recombination processes in atom-atom and ion-atom collisions (in the case of the symmetric atom-atom and ion-atom systems) in stellar hydrogen and helium plasmas are presented. The considered ion-atom radiation processes influence significantly on the optical characteristics of stellar plasma, and the considered chemi-ionization/recombination processes on the excited atomic energy level populations, as well as on the electron density. The consequence of the obtained results is that they should be taken into account for the modeling of photosohere and lower chromosphere of the Sun and similar star (hydrogen case) and white dwarfs atmospheres (helium case).
The influence of the H − H + − e and H 2 + − e chemi - recombination processes on the highly excited hydrogen atom population in the photosphere and lower part of the chromosphere has been considered. It has been shown that these chemi - recombination processes have an important role in the large region around the temperature minimum in the Solar atmosphere, where they are comparable to the other relevant recombination processes, or even dominant and that they should be taken into account for the modelling of the weakly ionized layers in the Solar atmosphere.
Astronomy & Astrophysics, 2007
Aims. To estimate the total contribution of the absorption processes λ + H + 2 (X 2 Σ + g) ⇒ H(1s) + H + and λ + H(1s) + H + ⇒ H + + H(1s) to the opacity of Solar atmosphere in UV and VUV region, and compare it with the contribution of other relevant radiative processes included in standard models. Methods. The strict quantum-mechanical method was used for the determination of the average cross-section for the photodissociation of the molecular ion H + 2 (X 2 Σ + g); the previously developed quasi-static method was used for determination of the corresponding spectral coefficient which characterizes the absorption charge exchange in H(1s) + H + collisions. Results. Spectral absorption coefficients characterizing the considered processes were calculated for the solar photosphere and lower chromosphere, within the 90 nm ≤ λ ≤ 370 nm spectral range; the total contribution of the considered processes to the solar opacity was estimated and compared to relevant radiative processes included in standard Solar models. Conclusions. In comparison with other absorption processes included in standard Solar models, the contribution of the considered processes in the UV and VUV regions is so important that they have to be taken into account in modeling the Solar photosphere and the lower chromosphere.