73 citations · 104 across the 2 of their papers we have counts for
4 papers · 1 filter
Uncertainties in Theoretical HeI Emissivities: HII Regions, Primordial Abundance, and Cosmological Recombination
R. L. Porter, G. J. Ferland, K. B. MacAdam +1
A number of recent works in astronomy and cosmology have relied upon theoretical He I emissivities, but we know of no effort to quantify the uncertainties in the atomic data. We an…
He~I Emission in the Orion Nebula and Implications for Primordial Helium Abundance
R. L. Porter, G. J. Ferland, K. B. MacAdam
We apply a recently developed theoretical model of helium emission to observations of both the Orion Nebula and a sample of extragalactic H II regions. In the Orion analysis, we el…
J-resolved He I emission predictions in the low-density limit
R. P. Bauman, R. L. Porter, G. J. Ferland +1
Determinations of the primordial helium abundance are used in precision cosmological tests. These require highly accurate He I recombination rate coefficients. Here we reconsider t…
Theoretical He I Emissivities in the Case B Approximation
R. L. Porter, R. P. Bauman, G. J. Ferland +1
We calculate the He I case B recombination cascade spectrum using improved radiative and collisional data. We present new emissivities over a range of electron temperatures and den…