Astronomy and Astrophysics – Astronomy
Scientific paper
Jun 1998
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998apj...500..507b&link_type=abstract
Astrophysical Journal v.500, p.507
Astronomy and Astrophysics
Astronomy
42
Atomic Processes, Plasmas, Radiative Transfer
Scientific paper
The J = 0 --> J' = 0 radiative transitions, usually viewed as allowed through two-photon decay, may also be induced by the hyperfine (HPF) interaction in atoms or ions having a nonzero nuclear spin. We compute new and review existing decay rates for the nsnp 3 PoJ --> ns2 1SJ'=0 transitions in ions of the Be (n = 2) and Mg (n = 3) isoelectronic sequences. The HPF induced decay rates for the J = 0 --> J' = 0 transitions are many orders of magnitude larger than those for the competing two-photon processes, and when present are typically 1 or 2 orders of magnitude smaller than the decay rates of the magnetic quadrupole (J = 2 --> J' = 0) transitions for these ions. Several HPF induced transitions are potentially of astrophysical interest in ions of C, N, Na, Mg, Al, Si, K, Cr, Fe, and Ni. We highlight those cases that may be of particular diagnostic value for determining isotopic abundance ratios and/or electron densities from UV or EUV emission-line data. We present our atomic data in the form of scaling laws so that, given the isotopic nuclear spin and magnetic moment, a simple expression yields estimates for HPF induced decay rates. We examine some UV and EUV solar and nebular data in light of these new results and suggest possible applications for future study. We could not find evidence for the existence of HPF induced lines in the spectra we examined, but we demonstrate that existing data have come close to providing interesting upper limits. For the planetary nebula SMC N2, we derive an upper limit of 0.1 for 13C/12C from Goddard High-Resolution Spectrograph data obtained by Clegg. It is likely that more stringent limits could be obtained using newer data with higher sensitivities in a variety of objects.
Aboussaid Abdellatif
Brage Tomas
Froese Fischer Charlotte
Godefroid Michel R.
Joensson Per
No associations
LandOfFree
Hyperfine Induced Transitions as Diagnostics of Isotopic Composition and Densities of Low-Density Plasmas 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 Hyperfine Induced Transitions as Diagnostics of Isotopic Composition and Densities of Low-Density Plasmas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hyperfine Induced Transitions as Diagnostics of Isotopic Composition and Densities of Low-Density Plasmas will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1331324