Tag Archives: active region

150. Photospheric Oscillations in and around Active Region 11158, including the Polarity Inversion Line

Contributed by Aimee Norton. Posted on January 20, 2021

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.

136. The Trigger Mechanism of Recurrent Solar Active Region Jets Revealed by the Magnetic Properties of a Coronal Geyser Site

Contributed by Alin Paraschiv. Posted on February 27, 2020

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.

135. Serial Flaring in an Active Region: Exploring Why Only One Flare is Eruptive

Contributed by Magnus Woods. Posted on February 26, 2020

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.

134. The First Numerical Modeling of Spontaneous Generation of δ-sunspots

Contributed by Shin Toriumi. Posted on December 17, 2019

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.

125. Solar Farside Magnetograms from Deep Learning Analysis of STEREO/EUVI Data

Contributed by Yong-Jae Moon. Posted on April 29, 2019

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.

119. Roles of Photospheric Motions and Flux Emergence in the Major Solar Eruption on 2017 September 6

Contributed by Rui Wang. Posted on January 31, 2019

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.

97. Successive X-class Flares and Coronal Mass Ejections Driven by Shearing Motion and Sunspot Rotation in Active Region NOAA 12673

Contributed by Xiaoli Yan. Posted on April 26, 2018

Shearing motions and sunspot rotations found in NOAA AR 12673 are believed to lead the free energy buildup and flux rope formation, which are responsible for the two successive X-class flares.

92. Photospheric Magnetic Properties of Active Regions: Br or Blos?

Contributed by Jordan A. Guerra Aguilera. Posted on March 26, 2018

The majority of flare forecasting methods rely on observations of magnetic field on the Sun’s surface, but which observable, Br or Blos, is a better predictor? Through comparing a few magnetic properties derived from both observables, this nugget gives some suggestion.