Dielectronic Recombination in Photoionized Gas: The Importance of Fine-structure Core Excitations

Details Dielectronic Recombination in Photoionized Gas: The Importance of Fine-structure Core Excitations Dielectronic Recombination in Photoionized Gas: The Importance of Fine-structure Core Excitations

Nov 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997apj...489l.115s&link_type=abstract

Astrophysical Journal Letters v.489, p.L115

Astronomy and Astrophysics

Astronomy

63

Atomic Data, Atomic Processes, Line: Formation, X-Rays: General

Scientific paper

At the low electron temperatures existing in photoionized gases with cosmic abundances, dielectronic recombination (DR) proceeds primarily via nlj-->nl^{'}_{j^{'}} excitations of core electrons ( Delta n=0 DR). At these temperatures, the dominant DR channel often involves 2p_{1/2}-->2p_{3/2} fine-structure core excitations, which are not included in LS-coupling calculations or the Burgess formula. Using the heavy-ion storage ring at the Max-Planck-Institut fur Kernphysik in Heidelberg, Germany, we have verified experimentally for Fe XVIII that DR proceeding via this channel can be significant in relation to other recombination rates, especially at the low temperatures characteristic of photoionized gases. At temperatures in photoionized gases near where Fe XVIII peaks in fractional abundance, our measured Fe XVIII to Fe XVII Delta n=0 DR rate coefficient is a factor of ~2 larger than predicted by existing theoretical calculations. We provide a fit to our measured rate coefficient for ionization equilibrium models. We have carried out new fully relativistic calculations using intermediate coupling, which include the 2p_{1/2}-->2p_{3/2} channel and agree to within ~30% with our measurements. DR via the 2p_{1/2}-->2p_{3/2} channel may also have spectroscopic implications, providing unique spectral signatures at soft X-ray wavelengths that could provide good electron temperature diagnostics.

Affiliated with

Also associated with

No associations

Rating

Dielectronic Recombination in Photoionized Gas: The Importance of Fine-structure Core Excitations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Dielectronic Recombination in Photoionized Gas: The Importance of Fine-structure Core Excitations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectronic Recombination in Photoionized Gas: The Importance of Fine-structure Core Excitations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1685692