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.
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.
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.
Contributed by David Korda. Posted on October 25, 2021
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.
Contributed by Bibhuti Kumar Jha. Posted on June 15, 2021
Magnetic-field dependence of active regions’ tilt angles are analyzed using the MDI and HMI observations for two solar cycles. The variation of the tilt angles with the maximum magnetic-field strength of the ARs indicates a nonlinear tilt quenching in the Babcock–Leighton process.
Contributed by Marta García Rivas. Posted on June 14, 2021
Similar to sunspots, the stable regions of pores on the Sun are also found to be defined by a critical value of the vertical component of the magnetic field. The critical value is comparable to that found in stable sunspots.
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.
Contributed by Suman Dhakal. Posted on October 14, 2020
Through studying three homologous eruptive events in an active region, the authors conclude that shearing motions and magnetic flux cancellation play a dominant role leading to the recurrent eruptions, and are key processes forming the eruptive structures.
Contributed by Leif Svalgaard. Posted on October 9, 2020
Using the solar axial magnetic dipole moment obtained prior to the solar minimum, the author predicts that the maximum sunspot number of Solar Cycle 25 is about 128.
Contributed by Julia Thalmann. Posted on September 10, 2020
Analysis of magnetic helicity of eruptive and confined flaring events indicates that non-potential magnetic helicity is indicative to eruptive potentials of active regions.