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The solar physics community is entering a golden era that is ripe with next-generation ground- and space-based facilities, advanced spectral inversion techniques, and realistic simulations that are becoming more computationally streamlined and efficient. With ever-increasing resolving power stemming from the newest observational telescopes, it becomes more challenging to obtain (near-)simultaneous measurements at high spatial, temporal and spectral resolutions, while operating at the diffraction limit of these new facilities. Hence, in recent years there has been increased interest in the capabilities integral field units (IFUs) offer towards obtaining the trifecta of high spatial, temporal and spectral resolutions contemporaneously. To date, IFUs developed for solar physics research have focused on mid-optical and infrared measurements. Here, we present an IFU prototype that has been designed for operation within the near-ultraviolet to mid-optical wavelength range, which enables key spectral lines (e.g., Ca ii H/K, H β , Sr ii, Na i D1/D2, etc.) to be studied, hence providing additional spectral coverage to the instrument suites developed to date. The IFU was constructed as a low-budget proof-of-concept for the upcoming 2 m class Indian National Large Solar Telescope and employs circular cross-section fibres to guide light into a Czerny–Turner configuration spectrograph, with the resulting spectra captured using a high quantum efficiency scientific CMOS camera. Mapping of each input fibre allows for the reconstruction of two-dimensional spectral images, with frame rates exceeding 20 s − 1 possible while operating in a non-polarimetric configuration. Initial commissioning of the instrument was performed at the Dunn Solar Telescope, USA, during August 2022. The science verification data presented here highlights the suitability of fibre-fed IFUs operating at near-ultraviolet wavelengths for solar physics research. Importantly, the successful demonstration of this type of instrument paves the way for further technological developments to make a future variant suitable for upcoming ground-based and space-borne telescope facilities. [ABSTRACT FROM AUTHOR]

Detailed study of the solar magnetic field is crucial to understand its generation, transport, and reversals. The timing of the reversals may have implications on space weather and thus identification of the temporal behaviour of the critical surges that lead to the polar field reversals is important. We analyse the evolution of solar activity and magnetic flux transport in Cycles 21–24. We identify critical surges of remnant flux that reach the Sun's poles and lead to the polar field reversals. We reexamine the polar field build-up and reversals in their causal relation to the Sun's low-latitude activity. We further identify the major remnant flux surges and their sources in the time-latitude aspect. We find that special characteristics of individual 11-yr cycles are generally determined by the spatiotemporal organization of emergent magnetic flux and its unusual properties. We find a complicated restructuring of high-latitude magnetic fields in Cycle 21. The global rearrangements of solar magnetic fields were caused by surges of trailing and leading polarities that occurred near the activity maximum. The decay of non-Joy and anti-Hale active regions resulted in the remnant flux surges that disturbed the usual order in magnetic flux transport. We finally show that the leading-polarity surges during cycle minima sometimes link the following cycle and a collective effect of these surges may lead to secular changes in the solar activity. The magnetic field from a Babcock–Leighton dynamo model generally agrees with these observations. [ABSTRACT FROM AUTHOR]

Solar prominences are structures of importance because of their role in polar field reversal. We study the long‐term variation of the time latitude distribution of solar prominences in this article. To accomplish this, we primarily used the digitized disc‐blocked Ca II K spectroheliograms as recorded from Kodaikanal Solar Observatory for the period of 1906–2002. For improving the data statistics we included full disc H α images from Meudon and Kanzelhohe Observatory, which are available after 1980. We developed an automated technique to identify the latitudinal locations of prominences in daily images from all three data sets. Derived time‐latitude distribution clearly depicted poleward migration of prominence structures for 10 cycles (15–24). Unlike previous studies, we separated the rate of poleward migration during onset and near pole, using piece‐wise linear fits. In most cases, we found acceleration in poleward migration with the change occurring near ±70° latitudes. The derived migration rates for such large number of solar cycles can provide important inputs toward understanding polar field buildup process. Key Points: Calibration of Ca II K disc‐blocked digitized images as recorded in Kodaikanal observatory for the period of 1906–2002Automated detection of prominences for 10 solar cycles (1906–2018) using images from Kodaikanal, Meudon and Kanzelhohe ObservatoryClear identification of nonlinear poleward migration, estimation of migration rates through piecewiselinear fits for 10 solar cycles [ABSTRACT FROM AUTHOR]

Outcomes of the workshop resulted in this Topical Collection which consists of seven comprehensive review papers. Oscillatory Processes in Solar and Stellar Coronae Edited by Valery M. Nakariakov, Dipankar Banerjee, Bo Li, Tongjiang Wang, Ivan Zimovets and Maurizio Falanga In 2019 the solar physics research community celebrated the 50th anniversary of the first detection of oscillatory processes in the solar corona as a quasi-periodic pulsation (QPP) of an X-ray and radio emission produced by a solar flare (Parks, G.K. Another review summarises the current state of the physical mechanisms and observational properties of QPPs in solar flares and considers their analogy with QPPs in stellar flares. [Extracted from the article]

Recent dedicated Hinode polar region campaigns revealed the presence of concentrated kilogauss patches of the magnetic field in the polar regions of the Sun, which are also shown to be correlated with facular bright points at the photospheric level. In this work, we demonstrate that this spatial intermittency of the magnetic field persists even up to the chromospheric heights. The small-scale bright elements visible in the bright network lanes of the solar network structure as seen in the Ca ii H images are termed network bright points. We use special Hinode campaigns devoted to the observation of polar regions of the Sun to study the polar network bright points during the phase of the last extended solar minimum. We use Ca ii H images of chromosphere observed by the Solar Optical Telescope. For magnetic field information, level-2 data of the spectro-polarimeter is used. We observe a considerable association between the polar network bright points and magnetic field concentrations. The intensity of such bright points is found to be correlated well with the photospheric magnetic field strength underneath with a linear relation existing between them. [ABSTRACT FROM AUTHOR]