Inverse Evershed flow is derived from chromospheric observations. Coupling these flow with the non force-free model, the authors find that the flow is driven along magnetic field lines connecting network elements with the outer penumbra by a gas pressure difference.
A segment of bald patch in AR 12673 disintegrated rapidly during solar cycle 24’s most intense flare. The horizontal magnetic field perpendicular to the polarity inversion line changed sign, while the parallel component permanently increased.
Instead of the center-annulus measurement geometry that time-distance helioseismology typically uses, a new one-sided center-arc measurement scheme is developed. This method shows advantage in measuring subsurface flows in in a close neighborhood of magnetic regions.
To search for signatures of Alfvénic waves in the solar photosphere, the authors analyze the oscillation amplitudes, phases and time-distance behavior between different observables in a sunspot umbra, its polarity inversion line, and surrounding area.
This study explores the magnetic triggers of recurrent active region jets. Both widely debated triggers, namely, flux cancellation and flux emergence, are associated alternatively to the apparently homologous jets.
Of three consecutive flares that occurred in a same active region within 4 hours, why were two non-eruptive and one eruptive? Non-linear force-free modeling suggest that breakout reconnection during the first two flares weakened the overlying field, allowing the flux rope to erupt in the third.
In an MHD simulation of flux emergence, a δ-sunspot is formed spontaneously by a collision of areas with opposite polarities. Driven by convective flows and counter-streaming flows, sheared polarity inversion lines form and flux ropes are created above.
A deep learning code is trained using the Sun’s front-side observations, HMI’s magnetograms and AIA’s 304Å EUV images, to establish a relation between magnetic field and EUV flux. Then the code is applied on the STEREO/EUVI 304Å data to obtain the Sun’s far-side magnetic field.
Both magnetic flux emergence and shearing flows occurred before the X9.3 flare on 2017 September 6. This analysis shows that shearing flows played a more significant role in leading to the helicity and electric currents buildup before the major eruption.
Heat flux delivered by magnetic reconnection is calculated based on a model using magnetic field observations, and the calculation is then compared with AIA EUV observations.