H-alpha redshifts as a diagnostic of solar flare heating

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185394· OSTI ID:6033857

Zarro, D M; Canfield, R C

The dynamics of chomospheric condensations formed during chromospheric evaporation are studied using coordinated X-ray and H-alpha observations of five solar flares. It is shown that the peak downflow velocity of condensations predicted by simple hydrodynamic compression of the chromosphere is in good agreement with empirical downflow velocities implied by impulsive phase H-alpha red wing Doppler shifts. It is found that the H-alpha wing redshift provides a diagnostic of the pressure excess in the evaporating region and the coronal energy flux driving chromospheric evaporation. Because preflare coronal pressures derived for each of the flares are high, it is suggested that the chromosphere succeeds in radiating excess flare heat energy without undergoing explosive chromospheric evaporation. 15 refs.

• Research Organization: National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center; NASA, Goddard Space Flight Center; Applied Research Corp., Greenbelt, MD; Hawaii, University, Honolulu
• OSTI ID: 6033857
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 338; ISSN ASJOA
• 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
CONDENSATES
DATA PROCESSING
DOPPLER EFFECT
ELECTROMAGNETIC RADIATION
EVAPORATION
HEATING
IONIZING RADIATIONS
PHASE TRANSFORMATIONS
PROCESSING
RADIATIONS
RED SHIFT
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR FLARES
STELLAR ATMOSPHERES
STELLAR CORONAE
X RADIATION