Open AccessTheoretical calculations of the H i , He i and He ii free–bound continuous emission spectra
Author(s) -
Ercolano B.,
Storey P. J.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10988.x
Subject(s) - photoionization , physics , atomic physics , ionization , spectral line , ion , emission spectrum , ab initio , hydrogen , quantum mechanics , astronomy
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 ≤ 10 5 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.