195 citations · 1.3k across the 49 of their papers we have counts for
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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…
Determination of the Physical Conditions of the Knots in the Helix Nebula from Optical and Infrared Observations
C. R. O'Dell, W. J. Henney, G. J. Ferland
[Abridged] We use new HST and archived images to clarify the nature of the knots in the Helix Nebula. We employ published far infrared spectrophotometry and existing 2.12 micron im…
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…
Determining the H+ Region/PDR Equation of State in Star Forming Regions
N. P. Abel, G. J. Ferland
The emission line regions of starburst galaxies and active nuclei reveal a wealth of spectroscopic information. A unified picture of the relationship between ionized, atomic, and m…
The H II Region/PDR Connection: Self-Consistent Calculations of Physical Conditions in Star-Forming Regions
N. P. Abel, G. J. Ferland, G. Shaw +1
We have performed a series of calculations designed to reproduce infrared diagnostics used to determine physical conditions in star forming regions. We self-consistently calculate…
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…