Yohkoh observation of a gamma-ray flare on November 6, 1997 Original Research Article

Yohkoh observed strong γ-ray emission from a flare (X92B) at 11:52 UT on November 6, 1997. We found that fluxes of narrow lines from elements with similar FIPs correlated with one another during the flare, while there is a temporal variation of a ratio of low-FIP (Mg, Si and Fe) to high-FIP (C, N, O and Ne) narrow line fluxes. The ratio measured for the decay phase was enhanced by about factor of 3 compared to those for the rise and peak phases. It suggests two possibilities: (1) the low-FIP/high-FIP elemental abundance ratio at the γ-ray emission site was increased in the decay phase or (2) the location of the γ-ray production site could have changed with time, progressing from the chromosphere-photosphere toward the corona.