Tag Archives: magnetic field

84. Abrupt and Permanent Changes of the Photospheric Magnetic Field During 75 flares observed with HMI

Contributed by Sebastián Castellanos Durán. Posted on January 16, 2018

Magnetic field changes associated with solar flares, observed by the SDO/HMI, are surveyed, and permanent changes of magnetic field are found in the majority of flare events. Properties of the magnetic field changes are further investigated.

79. Homologous Circular-Ribbon Flares Driven by Twisted Flux Emergence

Contributed by Zhi Xu. Posted on December 18, 2017

Two homologous circular-ribbon flares associated with two filament eruptions were observed and analyzed. The emergence of magnetic flux ropes helped to inject free energy into the region and drive the magnetic reconnection above it.

51. Magnetic Field Reconstruction Based on Sunspot Oscillations

Contributed by Johannes Löhner-Böttcher. Posted on April 25, 2016

We observed magnetoacoustic waves propagating along the magnetic field lines of a sunspot. Based on the wave periods and atmospheric characteristics, we reconstructed the magnetic field topology of the sunspot.

38. Subsurface Structure of Pores and Sunspots

Contributed by Robert Stein. Posted on May 12, 2015

Numerical simulation of sunspots indicate that different subsurface structures are possible. They may be deep coherent flux tubes or twisted spaghetti or shallow structures. It may well be that all the models proposed for sunspot structures are correct for some spot somewhere.

33. Comparing nonlinear force-free and potential field modeling using full-disk HMI data

Contributed by Tilaye Tadesse. Posted on January 23, 2015

We present potential filed and nonlinear force-free magnetic field (NLFFF) extrapolations of full-disk magnetogram observed by SDO/HMI instrument. The study shows that NLFFF model agrees significantly better with coronal magnetic loops as observed in SDO/AIA images.