Theoretical calculations of the H i, He i and He ii free–bound continuous emission spectra |
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Authors: | B Ercolano P J Storey |
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Institution: | sDepartment of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT |
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Abstract: | We present coefficients for the calculation of the continuous emission spectra of H i , He i and He ii due to electron–ion recombination. Coefficients are given for photon energies from the first ionization threshold for each ion to the n = 20 threshold of hydrogen (36.5 μm) , and for temperatures 100 ≤ T ≤ 105 K . The emission coefficients for He i are derived from accurate ab initio photoionization data. The coefficients are scaled in such a way that they may be interpolated by a simple scheme with uncertainties less than 1 per cent in the whole temperature and wavelength domain. The data are suitable for incorporation into photoionization/plasma codes and should aid with the interpretation of spectra from the very cold ionized gas phase inferred to exist in a number of gaseous clouds. |
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Keywords: | atomic data |
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