Determination of hyperfine-induced transition rates from observations of a planetary nebula
Observations of the planetary nebula NGC3918 made with the STIS instrument on the Hubble Space Telescope reveal the first unambiguous detection of a hyperfine-induced transition 2s2p P-3(0)o-->2s(2) S-1(0) in the berylliumlike emission line spectrum of N IV at 1487.89 Angstrom. A nebular model allows us to confirm a transition rate of 4x10(-4) sec(-1)+/-33% for this line. The measurement represent
