Abstract
We present a detailed study of coronal loop brightenings observed in an active region on the solar limb. These brightening loops show expanding and shrinking motions in EUV coronal line images and also show downflow along the loops in Lα and Hα images. By means of time-slice analysis of the images, we found that both the expanding and shrinking motions of the loops are not real motions of plasma but apparent motions like post-flare loops, where the loops at the different height are successively heated and cooled. From a temperature analysis, the time delay between the brightenings of hot 195 Å and cool Lα loops is found to be nearly equal to the time-scale of the conduction cooling. We conclude that these loop brightenings are sources of so called Hα coronal rains.
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Shimojo, M., Kurokawa, H. & Yoshimura, K. Dynamical Features and Evolutional Characteristics of Brightening Coronal Loops. Sol Phys 206, 133–142 (2002). https://doi.org/10.1023/A:1014939525194
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DOI: https://doi.org/10.1023/A:1014939525194