The influence of H- photo-dissociation and (H + H)- radiative collisions on the solar atmosphere opacity in UV and VUV regions

¹ Institute of Physics, PO Box 57, 11001 Belgrade, Serbia e-mail: ljuba@phy.bg.ac.yu
² Isaac Newton Institute of Chile, Yugoslavia Branch
³ Astronomical Observatory, Volgina 7, 11160 Belgrade 74, Serbia

Received: 31 January 2007
Accepted: 16 March 2007

Abstract

Aims.To estimate the total contribution of the absorption processes and 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 photo-dissociation of the molecular ion ; the previously developed quasi-static method was used for determination of the corresponding spectral coefficient which characterizes the absorption charge exchange in  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.