Impulsive phase soft X-ray blueshifts at a loop footpoint

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185296· OSTI ID:6795871

Zarro, D M; Slater, G L; Freeland, S L

Solar Maximum Mission (SMM) observations of a solar flare that occurred on May 24, 1987 are described. The event was noteworthy in that it was observed during the impulsive phase with the SMM X-ray Poly-chromator (XRP) pointed at a location associated with the chromospheric footpoints of a system of coronal loops. Density-sensitive line ratios at the flare site imply an initially large electron density of 5 x 10 to the 12th/cu cm, which decreased an order of magnitude during the flare. Spectral scans of the soft X-ray Mg XI line at the site reveal asymmetric blueshifted (200 km/s) profiles concurrent with impulsive hard X-ray emission. The blueshift amplitude was correlated with the intensity of hard X-rays (with a phase delay of about 30 s) and showed fluctuations on a time scale comparable with the variation of hard X-ray emission. These observations are interpreted as evidence for chromospheric evaporation produced by heating and expansion of footpoint plasma. 13 references.

• Research Organization: Applied Research Corp., Greenbelt, MD (SUA); Lockheed Research Laboratories, Palo Alto, CA (USA)
• OSTI ID: 6795871
• Journal Information: Astrophys. J.; (United States), Vol. 333
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
SOLAR FLARES
SOFT X RADIATION
CHROMOSPHERE
DOPPLER EFFECT
ELECTRON DENSITY
EXPANSION
FLUCTUATIONS
HARD X RADIATION
HEATING
SOLAR CORONA
SPATIAL RESOLUTION
ATMOSPHERES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS
RESOLUTION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
STELLAR ATMOSPHERES
STELLAR CORONAE
VARIATIONS
X RADIATION
640104* - Astrophysics & Cosmology- Solar Phenomena