@article{discovery10066, month = {November}, year = {2006}, number = {4}, volume = {372}, pages = {1875 -- 1878}, title = {Theoretical calculations of the HI, HeI and HeII free-bound continuous emission spectra}, publisher = {BLACKWELL PUBLISHING}, journal = {MON NOT R ASTRON SOC}, author = {Ercolano, B and Storey, PJ}, url = {https://discovery.ucl.ac.uk/id/eprint/10066/}, issn = {0035-8711}, 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 mu m), and for temperatures 100 {\ensuremath{<}}= T {\ensuremath{<}}= 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.}, keywords = {atomic data, TEMPERATURE-FLUCTUATIONS, PLANETARY-NEBULAE, RECOMBINATION, COEFFICIENTS} }