Work

Improved He I emissivities in the case B approximation

Year: 2012

Type: article

Abstract: 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).

Source: Monthly Notices of the Royal Astronomical Society Letters

DOI: 10.1111/j.1745-3933.2012.01300.x

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

Institutions: University of Georgia, University of Kentucky, University College London

Language: English

Topic: Atomic and Molecular Physics

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, Science and Technology Facilities Council

Award: G1845786289