Title: Temporal variability of YOHKOH SXT X-ray spectral irradiance
Author: K. B. Ramesh
Affil: Indian Institute of Astrophysics
Email: kbramesh@iiap.ernet.in
Abstract: Measure of the coronal emission is generally associated with the emergence of magnetic fields in the photosphere. earlier studies have shown that the brightness of the corona is directly related to the strength of the photospheric field. Some studies have shown that the brightness of the corona is related to the geometrical properties of the loops and other complexities in the active regions. We present here the results of the analysis of YOHKOH SXT X-ray spectral irradi- ance. We identify that the 10-20 A X-ray irradiance, when compared to other spectral ranges, correlates well with the photospheric magnetic flux on longer time scales. 2-10 A range seems to be more sensitive while others show large scatter with photospheric magnetic flux. Further analysis show that the entire spectral band (2-50 A) can be broadly classified into two groups, namely, 2-20 A and 20-50 A based on the similarities in their spectral behaviour.