Soft x-ray imaging of impulsive evaporation

Conference · Wed Jan 01 04:00:00 EST 1992 · American Astronomical Society, Bulletin; (United States)

OSTI ID:6646072

Hudson, H; Nitta, N; Strong, K; Takakura, T

The time development of a solar flare can often be broken into two phases, viz. the impulsive phase and the gradual phase. For many reasons the impulsive phase is known to result from powerful electron acceleration, to energies of tens of keV (and higher), with a total energy that is a large fraction of the energy subsequently radiated in various flare emissions. A grazing-incidence soft X-ray telescopes on board the Yohkoh spacecraft now enables us to study the few-keV properties of the impulsive phase for the first time. In a representative set of impulsive solar flares, we find an excellent match between the soft X-ray time profiles at the footpoints of coronal magnetic flux tubes and the hard X-ray impulsive emission. The hard X-ray images directly show the sites of the particle precipitation. The impulsive soft X-ray emission could arise directly as non-thermal bremsstrahlung, extending to the few-keV ranged; or it could contain contributions from the impulsively evaporating plasma seen during the process of the flare explosion from the chromosphere. We discuss these interpretations and the physics resulting from them.

• OSTI ID: 6646072
• Report Number(s): CONF-930189--
• Conference Information: Journal Name: American Astronomical Society, Bulletin; (United States) Journal Volume: 24:4
• Country of Publication: United States
• Language: English

Related Subjects

440100 -- Radiation Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BREMSSTRAHLUNG
CHROMOSPHERE
DETECTION
ELECTROMAGNETIC RADIATION
HARD X RADIATION
IMAGES
IONIZING RADIATIONS
MAGNETIC FLUX
MONITORING
PLASMA
RADIATION DETECTION
RADIATIONS
SOFT X RADIATION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR FLARES
SPACE VEHICLES
STELLAR ATMOSPHERES
STELLAR CORONAE
TELESCOPES
VEHICLES
X RADIATION