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Evidence for intense coronal prompt gamma-ray line emission from a solar flare

DOI

42

Citations

0

References

1994

Year

C. Barat, G. Trottet, Nicole Vilmer, J. P. Dezalay, Régine Talòn, R. Sunyaev, O. Terekhov, A. A. Kuznetsov
The Astrophysical Journal

Abstract

We present hard X-ray/gamma-ray measurements, obtained with the PHEBUS experiment onboard GRANAT, of the intense solar flare which occurred on 1991 June 1 at 14:56 UT beyond the east limb. The gamma-ray spectrum displays strong prompt lines in the 1-2 and 4-7 MeV energy ranges but no significant neutron capture line. Although the flare location prevents emission at heights below (3000-7000) km from being observed, the total fluence due to prompt nuclear lines in the 4-7 MeV range is found to be one of the largest measured so far. We argue that the prompt gamma-ray line emission takes place in the lower corona at densities below (10<SUP>11</SUP> to 5 x 10<SUP>11</SUP>)/cu cm.