Active region coronal loops - Structural and variability

• Published in: The Astrophysical journal. Supplement series Vol. 68; p. 371
• Main Authors: Haisch, Bernhard M., Strong, Keith T., Harrison, Richard A., Gary, G. A.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS 01.10.1988
• Subjects: Solar Physics
• ISSN: 0067-0049; 1538-4365
• DOI: 10.1086/191292

X-ray images of a pair of active region loops are studied which show significant, short time-scale variability in the line fluxes of O VIII, Ne IX, and Mg XI and in the 3.5-11.5 keV soft X-ray bands. Vector magnetograms and high-resolution UV images were used to model the three-dimensional characteristics of the loops. X-ray light curves were generated spanning four consecutive orbits for both loops individually, and light curves of the loop tops and brightest points were also generated. The largest variations involve flux changes of up to several hundred percent on time scales of 10 minutes. No significant H-alpha flare activity is reported, and loop temperatures remain in the four to six million K range. The decay phases of the light curves indicate radiative cooling, inhibition of conduction, and some type of 'continued heating' due to ongoing, underlying activity at the microflare level.