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Evolution of Magnetic Field Twist and Tilt in Active Region NOAA 10930
B. Ravindra, P. Venkatakrishnan, Sanjiv Kumar Tiwari
Magnetic twist of the active region has been measured over a decade using photospheric vector field data, chromospheric H_alpha data, and coronal loop data. The twist and tilt of t…
Are the photospheric sunspots magnetically force-free in nature?
Sanjiv Kumar Tiwari
In a force-free magnetic field, there is no interaction of field and the plasma in the surrounding atmosphere i.e., electric currents are aligned with the magnetic field, giving ri…
Helicity of the solar magnetic field
Sanjiv Kumar Tiwari
Helicity measures complexity in the field. Magnetic helicity is given by a volume integral over the scalar product of magnetic field {\bf B} and its vector potential {\bf A}. A dir…
Magnetic Non-Potentiality of Solar Active Regions and Peak X-Ray Flux of the Associated Flares
Sanjiv Kumar Tiwari, P. Venkatakrishnan, Sanjay Gosain
Predicting the severity of the solar eruptive phenomena like flares and Coronal Mass Ejections (CMEs) remains a great challenge despite concerted efforts for several decades. The a…
On the estimate of magnetic non-potentiality of sunspots derived using Hinode SOT/SP observations: Effect of polarimetric noise
Sanjay Gosain, Sanjiv Kumar Tiwari, P. Venkatakrishnan
The accuracy of Milne-Eddington (ME) inversions, used to retrieve the magnetic field vector, depends upon the signal-to-noise ratio (SNR) of the spectro-polarimetric observations.…
Magnetic Tension of Sunspot Fine Structures
P. Venkatakrishnan, Sanjiv Kumar Tiwari
The equilibrium structure of sunspots depends critically on its magnetic topology and is dominated by magnetic forces. Tension force is one component of the Lorentz force which bal…