%0 Journal Article
%@ 0035-8711
%A Casassus, S
%A Storey, PJ
%A Barlow, MJ
%A Roche, PF
%D 2005
%F discovery:10067
%I BLACKWELL PUBLISHING
%J MON NOT R ASTRON SOC
%K atomic data, atomic processes, line : identification, line : profiles, ISM : abundances, planetary nebulae : individual : NGC 6302, PLANETARY-NEBULAE, RADIOACTIVE AL-26, AGB STARS, SPECTROSCOPY, LINE
%N 4
%P 1386 - 1392
%T Hyperfine splitting of [Al VI] 3.66 mu m and the Al isotopic ratio in NGC 6302
%U https://discovery.ucl.ac.uk/id/eprint/10067/
%V 359
%X The core of planetary nebula NGC 6302 is filled with high-excitation photoionized gas at low expansion velocities. It represents a unique astrophysical situation in which to search for hyperfine structure (HFS) in coronal emission lines from highly ionized species. HFS is otherwise blended by thermal or velocity broadening. Spectra containing [Al vr] 3.66 mu m P-3(2) <- P-3(1), obtained with Phoenix on Gemini South at resolving powers of up to 75000, resolve the line into five hyperfine components separated by 20-60 km s(-1) as a result of the coupling of the I = 5/2 nuclear spin of Al-27 with the total electronic angular momentum J. The isotope Al-26 has a different nuclear spin of I = 5, and a different HFS, which allows us to place a 3 sigma upper limit on the Al-26/Al-27 abundance ratio of 1/33. We measure the HFS magnetic dipole coupling constants for [Al vr], and provide the first estimates of the electric quadrupole HFS coupling constants obtained through astronomical observations of an atomic transition.