Paula Cleggett-Haleim Headquarters, Washington, D.C. July 15, 1992 (Phone: 202/453-1547) EMBARGOED Until 1 p.m. EDT Jim Elliott Goddard Space Flight Center, Greenbelt, Md. (Phone: 301/286-6256) RELEASE: 92-112 COMPTON DISCOVERS "GAMMA RAY AFTERGLOW" ON THE SUN Solar scientists are puzzling over an unexpected "gamma ray afterglow" discovered on the sun by NASA's Compton Gamma Ray Observatory. The glow, a strong emanation of high-energy gamma rays, persisted for more than 5 hours after a solar flare explosion on June 11, 1991, Dr. James M. Ryan, of the University of New Hampshire, reported at a briefing at NASA Headquarters in Washington, D.C., today. A similar phenomenon occurred four days later, this time lasting more than 90 minutes, he said. One theory is that the glow resulted when protons, boosted to energies of tens and hundreds of millions of electron volts by magnetic processes in the explosion, were stored in a series of magnetic loops, Ryan explained. They apparently constituted a coronal arcade or so-called "magnetic slinky" in the sun's outer atmosphere or corona, he said. Protons are subatomic particles resulting from a nuclear reaction. If the theory is correct, Ryan said, the protons are stored at the sun much the same way as protons are stored in the Earth's Van Allen radiation belts. However, on the sun, he explained, they slowly leak out to produce the gamma rays seen by the Compton Observatory. - more - - 2 - Under those circumstances, scientists can draw an analogy from the Earth environment and apply it to the sun's environment, Ryan explained. Thus, if scientists' understanding of how particles behave in the Van Allen radiation belts can be applied to the sun, that knowledge would improve their understanding of what's happening on the sun, he continued. The work was accomplished using the Energetic Gamma Ray Experiment Telescope and Imaging Compton Telescope instruments on the observatory by Drs. Gottfried Kanbach and Mark McConnell of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and the University of New Hampshire, respectively. The Compton Gamma Ray Observatory is managed by the Goddard Space Flight Center, Greenbelt, Md., for NASA's Office of Space Science and Applications, Washington, D.C. - end - EDITORS NOTE: To illustrate this story, three photographs are available to the news media by calling NASA's Broadcast and Imaging Branch on 202/453-8375. The photo numbers are: Color B&W 92-HC-451 thru -453 92-H-501 thru -503