Chromospheric evaporation in a well-observed compact flare
We have observed the flare of 1980 May 7 1456 UT with several Solar Meaximum Mission instruments, in coordination with the Sacramento Peak Observatory vacuum tower telescope. From the X-ray data we are able to determine the total emission measure of all material at T>2 x 10/sup 6/ K, commonly attributed to chromospheric evaporation. Volume estimates from X-ray and H..cap alpha.. images lead to an estimate of the number of electrons in the soft X-ray plasma. Comparison of theoretical calculations of the H..cap alpha.. signature of an evaporated state of the chromosphere to H..cap alpha.. line profile observations shows that chromospheric evaporation indeed has taken place concurrently with the appearance of the X-ray plasma. We have determined the amount of material that has been evaporated from the chromosphere, relative to the preflare state. This leads us to the conclusion that more than enough material has been evaporated from the chromosphere to account for the material in the X-ray plasma. Taken together, the H..cap alpha.., soft, and hard X-ray images suggest that chromospheric evaporation is driven by two mechanisms. During the impulsive phase, there is evidence that chromospheric evaporation is due to flare-accelerated electrons. During the thermal phase, it appears to be driven by thermal conduction from the hot coronal plasma created earlier in the flare.
- Research Organization:
- Lockhead Palo Alto Research Laboratory, Lockhead Missiles and Space Co., Inc.
- OSTI ID:
- 5503432
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 263:1; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BALMER LINES
CHROMOSPHERE
ELECTROMAGNETIC RADIATION
EMISSION
ENERGY TRANSFER
EVAPORATION
HEAT TRANSFER
IMAGES
IONIZING RADIATIONS
PHASE TRANSFORMATIONS
PLASMA
RADIATIONS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR FLARES
SPECTRA
THERMAL CONDUCTION
X RADIATION
X-RAY SPECTRA