Excitation and deexcitation processes in atom-Rydberg atom collisions in helium-rich white dwarf atmospheres

Abstract

We aim to show the importance of non-elastic excitation and deexcitation processes in He * (n) + He(1s 2 ) collisions with the principal quantum number n ≥ 3 for helium-rich white dwarf atmospheres. We compare the efficiencies of these processes with those of the known non-elastic electron-He * (n) atom processes in the atmospheres of some DB white dwarfs. We show that in significant parts of the considered atmospheres, which contain weakly ionized layers (the ionization degree 10 −3 ), the influence of the studied atomRydberg atom processes on excited helium atom populations is dominant or at least comparable to the influence of the concurrent electron-He * (n)-atom processes.

The Collisional Atomic Processes of Rydberg Hydrogen and Helium Atoms: Astrophysical Relevance

“…The figure shows a monotonous decrease of rate coefficients with the increases of n and p, and a very slow increase as temperature increases, as concluded in [19,20]. Figure 8.…”

“…The values of excitation rate coefficients for 3000 K ≤ T ≤ 7000 K are from [18]. In the extended region of temperature coefficients are determined here using the semi-classical approach similar to that described in [19] or [20]. The de-excitation rate coefficients K n;n−p (T) are determined according to the principle of thermodynamical balance.…”

Influence of the (n-n')-mixing processes on the optical properties of the hydrogen clouds in the broad-line region of AGNs

“…On the basis of the resonant mechanism (Mihajlov et al, 2012;Srećković et al, 2013Srećković et al, , 2018c) the (n−n )-mixing processes (Eq. 1) are characterized as a product of the resonant energy exchange between the outer electron e and the electronic component of the subsystem H + + H (Fig.1).…”

Division B Commission 14 Working Group: Collision Processes

“…Excitation and charge transfer in H + H + collisions have been studied (Tseliakhovich et al 2012) and proton-Rydberg atom (Vrinceanu et al 2012), atom-Rydberg atom (Srećković et al 2013) collisions studied generally. Charge transfer, excitation and ionisation in collisions between ions and neutral atoms play important roles in a number of astrophysical environments.…”