Improved he i emissivities in the case b approximation

R. L. Porter, G. J. Ferland, P. J. Storey, M. J. Detisch

Research output: Contribution to journalLetterpeer-review

86 Scopus citations


We update our prior work on the case B collisional-recombination spectrum of He I to incorporate ab initio photoionization cross-sections. This large set of accurate, self-consistent cross-sections represents a significant improvement in He I emissivity calculations because it largely obviates the piecemeal nature that has marked all modern works. A second, more recent set of ab initio cross-sections is also available, but we show that those are less consistent with bound-bound transition probabilities than our adopted set. We compare our new effective recombination coefficients with our prior work and our new emissivities with those by other researchers, and we conclude with brief remarks on the effects of the present work on the He I error budget. Our calculations cover temperatures 5000 ≤ Te ≤ 25 000 K and densities 101 ≤ ne ≤ 1014 cm-3. Full results are available online (see Supporting Information).

Original languageEnglish
Pages (from-to)L28-L31
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Sep 2012


  • Atomic data

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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