ELECTRON IMPACT DISSOCIATION X (1)Sigma(+)(g) -˃ b (3)Sigma(+)(u) AND EXCITATIONS X (1)Sigma(+)(g) -˃ a (3)Sigma(+)(g) AND X (1)Sigma(+)(g) -˃ B (1)Sigma(+)(u) OF MOLECULAR HYDROGEN IN NONTHERMAL ASTROPHYSICAL PLASMAS

Abstract

We investigate the electronic transitions X 1Σ+ g → b 3Σ u +, X 1Σ+ g → a 3Σ g +, and X 1Σ+ g → B 1Σ u + of molecular hydrogen by studying electron impacts in astrophysical Lorentzian plasmas. Useful fitting formulae for the X 1Σ+ g → b 3Σ u +, X 1Σ+ g → a 3Σ g +, and X 1Σ+ g → B 1Σ u + excitation cross sections are employed in order to obtain the electronic excitation rate coefficients of H2 as functions of the spectral index and temperature. In low-temperature regions, it is found that the excitation rate coefficients $R_{b\,{}^3\Sigma _u^ + }$, $R_{a\,{}^3\Sigma _g^ + }$, and $R_{B\,{}^1\Sigma _u^ + }$ of H2 in non-Maxwellian plasmas are smaller than those in Maxwellian plasmas. However, in high-temperature regions, the excitation rate coefficients of H2 in non-Maxwellian plasmas are greater than those in Maxwellian plasmas. It is also shown that the X 1Σ+ g → b 3Σ u + excitation rate coefficient is the main contributor in low-temperature regions. In contrast, it is found that the X 1Σ+ g → B 1Σ u + electronic excitation is dominant in high-temperature regions.