HeH⁺ in Model Stellar Atmospheres

Citation

Norton, Robert Henry (1964) HeH⁺ in Model Stellar Atmospheres. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/YRJA-NP26. https://resolver.caltech.edu/CaltechETD:etd-10082002-163233

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Approximate quantum-mechanical calculations for the two lowest '[Sigma][superscript +] states of the helium hydride molecule ion HeH[superscript +] have been made. The molecular potential energy curves resulting from these calculations have been found to agree reasonably well with the results of other investigators. Using classical statistics for the distribution of internuclear separations, approximate absorption coefficients for radiative transitions between these two states have been obtained. A program to compute model stellar atmospheres in strict radiative equilibrium is described and was used to compute eight models with log g = 4.0 and effective temperatures between 9500[degrees]K and 30000[degrees]K. Total flux constant to within 1% was attained for these models excluding HeH[superscript +] as a source of opacity. When the final models were re-computed including the opacity of HeH[superscript +], radiative equilibrium was found to be destroyed by as much as 15%. Radiative equilibrium was re-established for the model with T[subscript e] = 16000[degrees] K, and a comparison between this model with and without HeH[superscript +] is given. It is found that HeH[superscript +] introduces a striking discontinuity in the continuous spectrum of the model at 1130 A; the ratio of the emergent monochromatic flux on the red side of the discontinuity to the flux on the violet side is 8.2 for the 16000[degrees]K model. It is concluded that the wings of the Lyman lines, except L[...], are probably weaker than previously supposed. In addition, numerical quadrature formulae of high accuracy and efficiency are given for integrals of the Schwarzschild-Milne type.

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