The non-symmetric ion–atom radiative processes in the stellar atmospheres

Abstract

The aim of this research is to show that the processes of absorption chargeexchange and photo-association in A + B + collisions together with the processes of AB + photo-dissociation in the case of strongly non-symmetric ion-atom systems, significantly influence the opacity of stellar atmospheres in ultraviolet (UV) and extreme UV (EUV) region. In this work, the significance of such processes for solar atmosphere is studied. In the case of the solar atmosphere the absorption processes with A = H and B = Mg and Si are treated as dominant ones, but the cases A = H and B = Al and A = He and B = H are also taken into consideration. The choice of just these species is caused by the fact that, of the species relevant for the used solar-atmosphere model, it was only for them that we could determine the necessary characteristics of the corresponding molecular ions, i.e. the molecular potential curves and dipole matrix elements. It is shown that the efficiency of the examined non-symmetric processes within the rather wide corresponding quasi-molecular absorption bands in the far-UV and EUV regions is comparable and sometimes even greater than the intensity of the known symmetric ion-atom absorption processes, which are included now in the models of the solar atmosphere. Consequently, the presented results suggest that the non-symmetric ion-atom absorption processes also have to be included ab initio in the corresponding models of the stellar atmospheres.

Mol-D a Database and a Web Service within the Serbian Virtual Observatory and the Virtual Atomic and Molecular Data Centre

“…Atomic and molecular databases in today's science have become essential for modeling and interpretation of data provided by observations and laboratory measurements (Srećković et al 2014, Mihajlov et al 2012, Mihajlov et al 2013, Marinković et al 2015. Nowadays, very important resources of such data are dissipated, presented in different, non-standardized ways, available through a variety of highly specialized and often not very well documented interfaces.…”

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

“…Helium atoms play an important role in astrophysics [4,31,32]. Ionization processes of excited states of helium and their inverse recombination processes are significant for helium plasmas in the very low-density environment which exists in stellar atmospheres with weakly ionized layers [21].…”

“…The helium molecular ion He + 2 is also present in stellar medium, as well as in the chemistry of the early universe [4,33,34]. Dissociative recombination (right side of Equation (4a)) is an inverse process occurring through the neutralization of the He + 2 ion.…”

“…Many fields in astrophysics, especially the modelling of various stellar atmospheres and the kinetics of stellar and other astrophysical plasmas, depend on data for atomic and molecular collisions [1][2][3][4][5][6]. Modern codes for stellar atmosphere modelling (e.g., [7,8]) require knowledge of atomic data, so the accuracy of these data becomes very important.…”

MOL-D: A Collisional Database and Web Service within the Virtual Atomic and Molecular Data Center

“…For the helium-rich white dwarf atmospheres A denotes He(1s 2 ) and X denotes, H(1s), and eventually C, O. (Mihajlov & Dimitrijevic 1992;Mihajlov et al 2013;Ignjatović et al 2014a). …”