Udaipur Solar Observatory

Abstract We present observations of and a magnetic reconnection scenario for a twin pair of “atypical flares” that occurred on 2022 April 22 in a quadrupolar magnetic configuration formed by two active regions. The spatiotemporal evolution of the two flares is examined using images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and from the ground-based Multi-Application Solar Telescope in Udaipur, India. Characteristic of atypical flares and indicative of slipping reconnection, the ribbons of each of our atypical flares: (1) do not spread apart; and (2) grow longer by the sequential brightening of new flare kernels. The two atypical flares are homologous and plausibly have homologous triggers. There are four additional pairs of flare ribbons, each from a different flaring event releasing much less energy than the atypical flares. Two of these four pairs are each made by a precursor, each possibly triggering one of the two atypical flares. The remaining two pairs accompany a filament’s activation, occurring twice within the span of the two atypical flares. Using a nonlinear force-free-field extrapolation model, we approximate the coronal magnetic field and find two quasi-separatrix layers (QSLs) that are nearly rooted in the flare ribbons of the atypical flares. The observations and the extrapolated field together suggest a scenario in which the nearly simultaneous occurrence of many reconnections between magnetic field lines crossing each other at small angles (slipping reconnection) within each of the two QSLs makes the observed pair of atypical flares.

Abstract Coronal jets are collimated plasma eruptions that are ubiquitous in the solar atmosphere. Believed to be triggered by magnetic reconnection, these jets can contribute to various phenomena, including coronal heating and particle acceleration. Coronal jets are a contemporary area of research, with their onset mechanism meriting further attention. Importantly, a subclass of jets, the blowout jets, is particularly interesting because of their broad spire, suggesting substantial 3D reconnection between open and closed field lines involving 3D null points. Consequently, here we explore the onset of a blowout jet associated with Active Region SPoCA 29093 detected by the Spatial Possibilistic Clustering Algorithm (SPoCA). This AR produced a C1.1-class flare on 2022 November 10, and we investigate it using a data-constrained magnetohydrodynamic simulation initiated with a non-force-free field extrapolation of the photospheric magnetic field. Key elements of the extrapolated field lines are the presence of a 3D null and a magnetic flux rope (MFR) colocated with the jet activity region, the evolution of which is further traced in the simulation. The simulation suggests that magnetic reconnection is responsible for the evolution of the MFR, leading to a near-simultaneous onset of the flare and jet as observed by the Atmospheric Imaging Assembly/Solar Dynamics Observatory. In particular, the simulation shows spontaneous creation and annihilation of 3D null pairs via magnetic reconnection near the jet region. Such spontaneous null pair generation, in principle, can trigger or contribute to coronal jets, opening up a new avenue for further research.

It is by now a common trope that youth climate activism has become a ‘global phenomenon’. Yet, it also has significant regional variations. This literature review analyses eighteen academic articles on the topic of youth climate activism in Asia. We found that the literature from Asia overall had ambitions to contextualise and nuance international scholarship on youth climate activism. This was achieved by emphasising social and cultural constructions of youth in different Asian contexts; by exploring inequality-related barriers for young people to enter into climate activism; by emphasising solidarity across classes and ages as a particular aspect of much Asian youth climate activism; and by showcasing the political restrictions in many Asian states, which inhibit (scholarship on) activism. We conclude that Asian avatars of youth climate activism have evolved in response to their distinct social, cultural, and political contexts, and that they challenge not easily transferable concepts such as ‘school strike’ and ‘future generations’. At the end, we offer suggestions for future research, including the need for going beyond desk studies when documenting discrete movements and for conceptualisations of youth climate activism that are inclusive of diverse contexts.

Aim/Purpose: This study aims to design and validate an evaluation instrument for a didactic strategy based on gamification, specifically adapted to e-learning contexts in higher education. It addresses the ongoing challenge of enhancing student motivation, engagement, and retention in virtual learning environments. Background: With the sustained growth of online education, higher education institutions need to develop and evaluate coherent pedagogical strategies that promote active learning. Although gamification has shown the potential to increase student participation, there is a lack of validated instruments to measure its effectiveness. This study responds to that need by proposing a validated framework for evaluating a gamified instructional model. Methodology: A non-experimental, descriptive, cross-sectional design with a mixed-methods approach was used. The Delphi method was applied, involving 33 experts who evaluated the validity and reliability of the proposed strategy. Content validity was assessed using the Content Validity Coefficient (CVC), and reliability was confirmed through Cronbach’s alpha. Contribution: This study provides an empirically validated instrument for implementing and evaluating gamification-based strategies in e-learning environments. It offers a structured and reliable tool for enhancing instructional planning and student engagement in virtual settings. Findings: Experts showed high levels of agreement regarding the structure, clarity, and pedagogical coherence of the strategy’s components. The instrument demonstrated strong reliability and validity, confirming its suitability for evaluating gamified instructional models. The proposed framework is expected to inform future research and serve as a practical guide for educators integrating gamification into online learning. Recommendations for Practitioners: Educators and instructional designers should consider integrating gamification elements such as narratives, levels, and rewards to enhance student motivation and participation in e-learning environments. Recommendation for Researchers: Future research should explore the long-term effects of gamification on academic performance and assess its adaptability across different disciplines and educational levels. Impact on Society: The validated gamification strategy can improve online education accessibility and effectiveness, reduce dropout rates, and foster more engaging and interactive learning experiences. Future Research: Further studies should investigate how different game mechanics influence student engagement and learning outcomes in diverse cultural and academic settings.

The hosting capacity (HC) of additional distributed energy resources (DERs) integrated into the distribution grids is limited by multiple technical factors defined by international and national regulations. In this paper, a generic methodology for the HC calculation is presented considering the HC influence on other interconnected grids. The technical constraints include bounds for the voltage quality, and the loading of grid assets. Next, a specific use case based on the Spanish regulation is developed, considering various limits for the loading of grid assets, voltage quality, power capacity, and the short-circuit power ratio. For mesh grids, the unavailability of supply through N-1 analyses is also evaluated. It is evident that the HC is more realistically calculated due to the impact of interconnected grids, while the constraints of the Spanish regulation can restrict further the HC.

Three-dimensional (3D) magnetic nulls are abundant in the solar atmosphere, as been firmly established through contemporary observations. They are established to be important magnetic structures in, for example, jets and circular ribbon flares. While simulations and extrapolations support this, the mechanisms behind 3D null generation remain an open question. Recent magnetohydrodynamics (MHD) simulations propose that magnetic reconnection is responsible for both generating and annihilating 3D nulls, a novel concept. However, these simulations began with initial magnetic fields already supporting pre-existing nulls, raising the question of whether magnetic reconnection can create nulls in fields initially devoid of them. Previously, this question was briefly explored in a simulation with an initial chaotic magnetic field. However, the study failed to precisely identify locations, topological degrees, and natures (spiral or radial) of nulls, and it approximated magnetic reconnection without fully tracking field line in time. In this paper these findings are revisited in light of recent advancements and tools used to locate and trace nulls, along with the tracing of field lines, through which the concept of generation/annihilation of 3D nulls from chaotic fields is established in a precise manner.

Coronal fan loops rooted in sunspot umbra show outward propagating waves with subsonic phase speed and a period around 3 min. However, their source region in the lower atmosphere is still ambiguous. We performed multi-wavelength observations of a clean fan loop system rooted in a sunspot utilizing data from the Interface Region Imaging Spectrograph (IRIS) and the Solar Dynamics Observatory (SDO). We explored the less studied property of frequency modulation of these 3-min waves from the photosphere to the corona, and identified periodicities in the ranges of 14-20 min, and 24-35 min. Based on our findings, we interpret that the 3-min slow waves observed in the coronal fan loops are driven by 3-min oscillations observed at the photospheric footpoints of these fan loops in the umbral region. We also investigated possible connections between the 3-min and 5-min oscillations observed at the photosphere, which are still poorly understood. Our results provide clear evidence of magnetic coupling of the solar umbral atmosphere through the propagation of 3-min waves along the fan loops at different atmospheric heights.

Extreme-ultraviolet (EUV) waves are one of the large-scale phenomena on the Sun. They are defined as large propagating fronts in the low corona with speeds ranging from a few tens km s−1 to several 1000 km s−1. They are often associated with solar filament eruptions, flares, and/or coronal mass ejections (CMEs). EUV waves exhibit various features, including wave and non-wave components, stationary fronts, reflection, refraction, and mode conversion. Additionally, they can hit the nearby coronal loops and filaments/prominences during their propagation, triggering oscillations. These oscillations in loops and filaments/prominences enable us to diagnose coronal parameters such as the strength of the coronal magnetic field. In this article, we present the different observed features of the EUV waves along with existing models.