Category Archives: Magnetic Field

182. The magnetic topology of the inverse Evershed flow

Contributed by Avijeet Prasad. Posted on July 29, 2022

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.

176. On the Hemispheric Bias Seen in Vector Magnetic Field Data

Contributed by Yang Liu. Posted on March 22, 2022

The authors show that the new inversion code for the HMI’s vector field reduces the number of pixels that reverse signs after passing the central meridian. The analysis also reveals that the radial components of the HMI’s vector magnetic fields have a hemispheric bias, too.

175. Solving a long-standing problem with the HMI data products

Contributed by Ana Griñón-Marín. Posted on March 21, 2022

For weak magnetic regions, HMI’s vector magnetic fields are known to give ambiguous signs in the east-west direction. A new inversion strategy is developed to address this problem, and the follow-up analysis shows that the new code improves HMI’s weak vector magnetic fields.

174. Toward Improved Understanding of Magnetic Fields Participating in Solar Flares: Statistical Analysis of Magnetic Fields within Flare Ribbons

Contributed by Maria Kazachenko. Posted on February 24, 2022

Through analyzing a number of active regions, this analysis finds that while flares are guided by the physical properties that scale with AR size, CMEs are guided by mean properties, with little dependence on the amount of shear at the polarity inversion line or the net current.

173. Buildup of the Magnetic Flux Ropes in Homologous Solar Eruptions

Contributed by Rui Wang. Posted on February 17, 2022

This analysis shows that a new bipolar emergence, whose positive polarity collided with the pre-existing negative polarity, in AR11283 led to energy and helicity buildup in the form of magnetic flux ropes. Recurrent energy releases caused a few homologous CMEs from this region.

168. Introducing the SPEAR Catalogue from HMI Data

Contributed by Aimee Norton. Posted on October 29, 2021

In order to make the properties of magnetic features observed by SDO/HMI more accessible, the Solar Photospheric Ephemeral and Active Region (SPEAR) catalogue has been created as an easy-to-read tabulated text file. Tilt angles from the SPEAR catalogue are shown as a histogram (top) and as a function of latitude (bottom) with colors indicating all regions (blue), regions with anti-Joy (red), and anti-Hale (purple) tilts. Over 40% of regions disobey the laws of Joy and Hale.