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HINODE Observations of Coherent Lateral Motion of Penumbral Filaments during a X-class Flare
S. Gosain, P. Venkatakrishnan, Sanjiv Kumar Tiwari
The X-3.4 class flare of 13 December 2006 was observed with a high cadence of 2 minutes at 0.2 arc-sec resolution by HINODE/SOT FG instrument. The flare ribbons could be seen in G-…
On the Absence of Photospheric Net Currents in Vector Magnetograms of Sunspots Obtained From Hinode (SOT/SP)
P. Venkatakrishnan, Sanjiv Kumar Tiwari
Various theoretical and observational results have been reported regarding the presence/absence of net electric currents in the sunspots. The limited spatial resolution of the earl…
Global Twist of Sunspot Magnetic Fields Obtained from High Resolution Vector Magnetograms
Sanjiv Kumar Tiwari, P. Venkatakrishnan, K. Sankarasubramanian
The presence of fine structures in the sunspot vector magnetic fields has been confirmed from Hinode as well as other earlier observations. We studied 43 sunspots based on the data…
Effect of Polarimetric Noise on the Estimation of Twist and Magnetic Energy of Force-Free Fields
Sanjiv Kumar Tiwari, P. Venkatakrishnan, Sanjay Gosain +1
The force-free parameter , also known as helicity parameter or twist parameter, bears the same sign as the magnetic helicity under some restrictive conditions. The single global…
Evolution of helicity in NOAA 10923 over three consecutive solar rotations
Sanjiv Kumar Tiwari, Jayant Joshi, Sanjay Gosain +1
We have studied the evolution of magnetic helicity and chirality in an active region over three consecutive solar rotations. The region when it first appeared was named NOAA10923 a…