Category Archives: Magnetic Field

114. What We Learned from a Long-term Study of Sunspot Physical Parameters

Contributed by Jing Li. Posted on November 20, 2018

Physical parameters, including sunspots tilt angles, total magnetic flux, polarity pole separations, and magnetic areas, are measured for most sunspot groups in solar cycles 23 and 24. Differences between Hale and anti-Hale sunspots in separate hemispheres and cycles are studied statistically.

113. What Makes CME-producing Solar Eruptions Happen?  Insight from Coronal Jets

Contributed by Alphonse Sterling. Posted on September 28, 2018

Jets resulting from eruption of minifilaments have lots of similarities to CMEs resulting from eruptions of large-scale filaments. This study on occurrences of jets can shed light on our understanding of what causes CME eruptions.

111. Synoptic Q-Maps — Insight into the Topology of the Coronal Magnetic Field

Contributed by Todd Hoeksema. Posted on September 26, 2018

Synoptic Q-maps, which display a geometric parameter describing the squashing factor of elemental flux tubes, are computed using both HMI and MDI magnetic field observations. These maps are useful for understanding coronal configurations relevant to space weather.

99. A Comparative Study between A Failed and A Successful Eruption Initiated from the Same Polarity Inversion Line in AR 11387

Contributed by Lijuan Liu. Posted on May 22, 2018

Two flares occurred in a same active region above a same polarity inversion line, but one had a failed CME eruption but another one had a successful CME eruption. This study explored why that was the case.

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.

96. Evaluation of Applicability of a Flare Trigger Model
 Based on a Comparison of Geometric Structures


Contributed by Yumi Bamba. Posted on April 23, 2018

A sample of 32 flare events are analyzed to evaluate how these events agree with a flare-triggering model, which examines shear angles of large-scale magnetic field and small-scale dipole field during the flares’ precursor brightening.