Momentum balance in four solar flares

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168240· OSTI ID:6956099

Canfield, R C; Metcalf, T R; Zarro, D M; Lemen, J R ^[1]

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1. Hawaii Univ., Honolulu (USA) California Univ., San Diego (USA) Applied Research Corp., Greenbelt, MD (USA) Lockheed Research Laboratories, Palo Alto, CA (USA)

Solar Maximum Mission soft X-ray spectra and National Solar Observatory (Sacramento Peak) H-alpha spectra were combined in a study of high-speed flows during the impulsive phase of four solar flares. In all events, a blue asymmetry (indicative of upflows) was observed in the coronal Ca XIX line during the soft X-ray rise phase. In all events a red asymmetry (indicative of downflows) was observed simultaneously in chromospheric H-alpha. These oppositely directed flows were concurrent with impulsive hard X-ray emission. Combining the velocity data with estimates of the density based on emission measurements and volume estimates, it is shown that for the impulsive phase as a whole the total momentum of upflowing soft X-ray plasma equaled that of the downflowing H-alpha plasma, to within an order of magnitude, in all four events. Only the chromospheric evaporation model predicts equal total momentum in the upflowing soft X-ray-emitting and downflowing H-alphba-emitting materials. 54 refs.

• OSTI ID: 6956099
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 348; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BALMER LINES
CHROMOSPHERE
ELECTROMAGNETIC RADIATION
FLUID FLOW
FLUID MECHANICS
GAS FLOW
HYDRODYNAMICS
IONIZING RADIATIONS
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
RADIATIONS
SOFT X RADIATION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR FLARES
SPECTRA
STELLAR ATMOSPHERES
STELLAR CORONAE
X RADIATION
X-RAY SPECTRA