Ram Ajor Maurya
Articles written in Journal of Astrophysics and Astronomy
Volume 29 Issue 1-2 March 2008 pp 103-105
We study the magnetic and velocity field evolution in the two magnetically complex active regions NOAA 10486 and NOAA 10488 observed during October–November 2003.We have used the available data to examine net flux and Doppler velocity time profiles to identify changes associated with evolutionary and transient phenomena. In particular, we report detection of rapid moving features observed in NOAA 10486 during the maximum phase of the X17.2/4B superflare of October 28, 2003. The velocity of this moving feature is estimated around 40 km/s, i.e., much greater than the usual H𝛼 flare-ribbons’ separation speed of 3–10 km/s, but similar to the velocity of seismic waves, i.e., ∼ 45 km/s reported earlier by Kosovichev & Zharkova (1998).
Volume 29 Issue 1-2 March 2008 pp 249-252
We reinvestigate the problem of Hα intensity oscillations in large flares, particularly those classified as X-class flares. We have used high spatial and temporal resolution digital observations obtained from Udaipur Solar Observatory during the period 1998–2006 and selected several events. Normalized Lomb–Scargle periodogram method for spectral analysis was used to study the oscillatory power in quiet and active chromospheric locations, including the flare ribbons.
Volume 40 | Issue 5
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