Solar Physics最新文献

{"title":"Aditya Solar Wind Particle Experiment (ASPEX) on Board Aditya—L1: The Solar Wind Ion Spectrometer (SWIS)","authors":"Prashant Kumar,&nbsp;Bhas Bapat,&nbsp;Manan S. Shah,&nbsp;Hiteshkumar L. Adalja,&nbsp;Arpit R. Patel,&nbsp;Pranav R. Adhyaru,&nbsp;M. Shanmugam,&nbsp;Dibyendu Chakrabarty,&nbsp;Swaroop B. Banerjee,&nbsp;K. P. Subramanian,&nbsp;Aveek Sarkar,&nbsp;Tinkal Ladiya,&nbsp;Jacob Sebastian,&nbsp;Abhishek Kumar,&nbsp;Sushil Kumar,&nbsp;Nishant Singh,&nbsp;M. B. Dadhania,&nbsp;Santosh V. Vadawale,&nbsp;Shiv Kumar Goyal,&nbsp;Neeraj Kumar Tiwari,&nbsp;Aaditya Sarda,&nbsp;Deepak Kumar Painkra,&nbsp;Piyush Sharma,&nbsp;Abhishek J. Verma,&nbsp; Yogesh,&nbsp;P. Janardhan,&nbsp;Anil Bhardwaj","doi":"10.1007/s11207-025-02443-x","DOIUrl":"10.1007/s11207-025-02443-x","url":null,"abstract":"<div><p>The Solar Wind Ion Spectrometer (SWIS) instrument is a part of the Aditya Solar Wind Particle Experiment (ASPEX), one of the three in situ observation instruments on board India’s Aditya-L1 spacecraft. SWIS comprises two Top-Hat analysers (THA-1 and THA-2), which have a 360^∘ angular coverage in the ecliptic plane and in the plane perpendicular to the ecliptic plane, respectively, with opening angles of <span>(pm 1.5^{circ })</span>. Both are electrostatic scanning instruments designed to measure the flux, the energy distribution and the angular distribution of the solar wind particles, covering the energy range of 0.1 – 20.0 keV with a 5 s cadence and 8% energy resolution. THA-1 has an additional species separation capability, based on a magnetic mass analyser (MMA) primarily designed to separate H⁺ and He²⁺, giving us the ability to measure the energy-, angle-, and time-dependent variation of the all-important helium abundance ratio in the ambient solar wind and in transient structures like interplanetary coronal mass ejections (ICME), stream interaction regions (SIR) passing through the location of the spacecraft. Over the life of the mission, the multidirectional observational capabilities of SWIS are expected to provide valuable data on the variations in the primary composition of solar wind, its velocity distribution, and its directional anisotropy. The SWIS instrument will also capture the low-energy end of the supra-thermal population in the solar wind. A special feature of the instrument is its user-level configurability for specific studies. The instrument will generate detailed information on helium abundance, its variability, and its connection to the solar wind speed.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143698530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aditya Solar Wind Particle Experiment on Board Aditya–L1: The Supra-Thermal and Energetic Particle Spectrometer","authors":"Shiv Kumar Goyal,&nbsp;Neeraj Kumar Tiwari,&nbsp;Arpit R. Patel,&nbsp;M. Shanmugam,&nbsp;Santosh V. Vadawale,&nbsp;Dibyendu Chakrabarty,&nbsp;Jacob Sebastian,&nbsp;Bijoy Dalal,&nbsp;Piyush Sharma,&nbsp;Aveek Sarkar,&nbsp;Aaditya Sarda,&nbsp;Tinkal Ladiya,&nbsp;Abhishek J. Verma,&nbsp;Nishant Singh,&nbsp;Sushil Kumar,&nbsp;Deepak Kumar Painkra,&nbsp;Prashant Kumar,&nbsp;Manan S. Shah,&nbsp;Pranav R. Adhyaru,&nbsp;Hiteshkumar L. Adalja,&nbsp;Swaroop B. Banerjee,&nbsp;K. P. Subramanian,&nbsp;Bhas Bapat,&nbsp;M. B. Dadhania,&nbsp;Abhishek Kumar,&nbsp;P. Janardhan,&nbsp;Anil Bhardwaj","doi":"10.1007/s11207-025-02441-z","DOIUrl":"10.1007/s11207-025-02441-z","url":null,"abstract":"<div><p>Aditya–L1, the first dedicated Indian solar mission, was launched on 02 September 2023 and has been placed in a halo orbit around the first Lagrange point (L1) of the Sun-Earth system on 06 January 2024. Aditya Solar wind Particle EXperiment (ASPEX) is one of the three in situ science experiments on board the Aditya–L1 mission that provides measurements of primarily protons and alpha particles in the solar wind, suprathermal, and energetic particles in the energy range from 100 eV to 6 MeV/nucleon. ASPEX consists of two independent spectrometers: the Solar Wind Ion Spectrometer (SWIS: 100 eV – 20 keV) and Supra Thermal and the Energetic Particle Spectrometer (STEPS: 20 keV/nucleon – 6 MeV/nucleon). In this article, we provide the details of the STEPS configuration, ground calibration, and in–flight performance. After the launch of Aditya–L1, two STEPS units were switched–on during the Earth-bound phase on 10 September 2023. STEPS has carried out measurements in the Earth-bound orbit for altitudes <span>(gtrsim 8)</span> R_<i>E</i>, and also in the cruise phase from the Earth to the halo orbit, and has been continuously operational after insertion to the L1 orbit. The performance of STEPS is as expected during all the phases of the mission so far and all its observations are found to be consistent with similar measurements from other contemporary instruments at the L1 point.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of Photospheric Magnetic Field and Electric Currents During the X1.6 Flare in Active Region NOAA 12192","authors":"Partha Chowdhury,&nbsp;Belur Ravindra,&nbsp;Sanjiv Kumar Tiwari","doi":"10.1007/s11207-025-02451-x","DOIUrl":"10.1007/s11207-025-02451-x","url":null,"abstract":"<div><p>The dynamics of magnetic fields in the Sun’s active regions play a key role in triggering solar eruptions. Studies have shown that changes in the photosphere’s magnetic field can destabilize the large-scale structure of the corona, leading to explosive events such as flares and coronal mass ejections (CMEs). This paper delves into the magnetic field evolution associated with a powerful X1.6 class flare that erupted on October 22, 2014, from the flare-rich active region NOAA 12192. We track these changes using high-resolution vector magnetograms from the Helioseismic and Magnetic Imager (HMI) on NASA’s Solar Dynamic Observatory (SDO). Our analysis reveals that a brightening, a precursor to the flare, began near the newly emerged, small-scale bipolar flux regions. During the X1.6 flare, the magnetic flux in both polarities displayed emergence and cancellation. The total current within the active region peaked during the flare. However, it is a non-CME event, and the ratio of direct-to-return current value remains close to 1. The large flare in this active region occurred when the net current in both polarities attained the same sign. This implies that the Lorentz force, a consequence of the interaction between currents and magnetic fields, would have pushed the field lines together in this scenario. This reconnection of opposing magnetic fields is believed to be the driving force behind the major flare in this active region.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"N-S Asymmetry and Periodicity of Solar Activity from Solar Cycles 21 – 24","authors":"S. F. Ibrahim,&nbsp;N. K. Hafez,&nbsp;M. A. El-Borie,&nbsp;A. A. Bishara,&nbsp;A. M. El-Taher","doi":"10.1007/s11207-025-02442-y","DOIUrl":"10.1007/s11207-025-02442-y","url":null,"abstract":"<div><p>Continuous wavelet power spectrum approach has been utilized to examine the short- and long-term fluctuations of solar plage area (PA), solar flare index (SFI), and sunspot numbers (SSNs) from 1976 to 2022. Based on the distribution of monthly data from the hemisphere SSNs, the monthly average of the solar parameters under consideration has been divided into northern and southern groups. Besides, the N-S asymmetry, the periodicity, the interconnection, and phase synchronization between the northern and southern groups of the solar flare index and plage area have been presented using the wavelet technique. The findings show that the northern group of PAs has short and intermediate periods of 0.9, 1.5, 2.5, and 3.5 years, whereas the southern group shows the prevalence of periods of 0.7, 1.9, and 3.2 years. In contrast, the northern group of SFI displays periods of 0.6, 0.8, 1.5, and 3.5 years, whereas the southern group confirms the presence of discrete periods of 0.7 and 1.9 years. The PA and SFI data sets for the Solar Cycles (SCs) 21 – 24 show little correlation and fewer short periods in the cross-wavelet power spectra (XWT) and wavelet coherence (WTC) spectra between the northern and southern hemispheres.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-025-02442-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Fluxgate Magnetometer (MAG) on Board Aditya-L1 Spacecraft","authors":"Vipin K. Yadav,&nbsp;Y. Vijaya,&nbsp;B. Krishnam Prasad,&nbsp;P. T. Srikar,&nbsp;Monika Mahajan,&nbsp;K. V. L. N. Mallikarjun,&nbsp;Syeeda N. Zamani,&nbsp;Satyanarayana Kumari B.,&nbsp;K. A. Lohar,&nbsp;M. M. Kandpal,&nbsp;S. Narendra,&nbsp;Vijay S. Rai,&nbsp;Abhijit A. Adoni,&nbsp;D. R. Veeresha,&nbsp;Smaran T.S.,&nbsp;Kalpana A.,&nbsp;Nandita Srivastava,&nbsp;Geeta Vichare","doi":"10.1007/s11207-025-02440-0","DOIUrl":"10.1007/s11207-025-02440-0","url":null,"abstract":"<div><p>The Fluxgate Magnetometer (MAG) is one of the seven instruments on board Aditya-L1 spacecraft to sample the local magnetic field environment around the first Lagrangian point (L1) while continuously observing the Sun. These in situ magnetic field measurements are crucial in detecting coronal mass ejections (CMEs), as well for space weather studies in the vicinity of the Earth, and the apparent detection of solar plasma wave signatures at L1. The MAG payload has a set of fluxgate magnetic sensors mounted on the Sun-viewing panel deck and is configured to deploy along the negative roll direction of the spacecraft. Two sets of triaxial fluxgate sensors are mounted on a 6-m long boom with one set at the tip of the boom and the other at the centre of the boom around 3 m away from the spacecraft towards the boom tip. The boom is mounted to be deployed along the –roll axis of the spacecraft. The power supply and the processing electronics for the MAG payload are enclosed in a box, which is placed inside the +yaw panel of the spacecraft. Each of the two triaxial fluxgate sensors measures the interplanetary magnetic field vectors at L1 in the default range of ± 256 nT per axis once every 125 ms. The observed magnetic field data is time stamped at the spacecraft with the on board clock and transmitted to ground once every day when the visibility is for 12 hours, along with the house-keeping parameters, ephemeris, and the science data from the other six payloads.</p><p>In this technical paper, the Aditya-L1 MAG instrument details are presented, along with the initial observations in the halo-orbit around L1.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ASHI: The All Sky Heliospheric Imager: August 22 – 26, 2022, NASA Balloon Flight and Image Data Reduction Analysis","authors":"Bernard V. Jackson,&nbsp;Matthew Bracamontes,&nbsp;Andrew Buffington,&nbsp;Stuart Volkow,&nbsp;Stephen White,&nbsp;Mario M. Bisi,&nbsp;Edward Stephan,&nbsp;Philippe Leblanc,&nbsp;Ron Quillin","doi":"10.1007/s11207-025-02448-6","DOIUrl":"10.1007/s11207-025-02448-6","url":null,"abstract":"<div><p>We have conceived, designed, and evaluated components for an All Sky Heliospheric Imager (ASHI), suitable for flight on future space missions both in Earth orbit and in deep space. ASHI was tested in the summer of 2022 on a NASA-sponsored topside balloon flight; in this paper, we highlight the images taken and the current state of the data reduction from this instrument’s successful overnight flight. The data reduction involves the removal of starlight, zodiacal light, and atmospheric glow to enable the measurements of the outward flow of heliospheric structures. A key photometric specification for ASHI is better than 0.05% differential photometry in one-degree sky bins at 90° elongation. The ASHI balloon flight exceeded expectations and reached to a background white light level of small-scale solar wind structure variations beyond ∼ 60° from the Sun considerably lower than this. Used as a simple, light weight (∼ 8 kg) and relatively inexpensive spaceflight instrument, ASHI has the principal objective of providing a minute-by-minute and day-by-day near real time acquisition of precision Thomson-scattering photometric maps of the inner heliosphere over nearly a hemisphere of sky starting a few degrees from the Sun. This has large potential benefits for improving space-weather nowcast and forecast capabilities of small heliospheric structures.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-025-02448-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Connections Between the Quiet Corona Magnetic Topology and the Velocity Field of Propagating Disturbances","authors":"Nina Stankovic,&nbsp;Huw Morgan","doi":"10.1007/s11207-025-02446-8","DOIUrl":"10.1007/s11207-025-02446-8","url":null,"abstract":"<div><p>The magnetic field of the low corona above quiet Sun regions is extremely challenging to observe directly, and the topology is difficult to discern from extreme ultraviolet (EUV) image data due to the lack of distinct loops that are present in, for example, active regions. We aim to show that the velocity field of faint propagating disturbances (PD) observed on-disk in the quiet corona can be interpreted in terms of the underlying magnetic topology. The PD are observed in Atmospheric Imaging Assembly/Solar Dynamics Observatory (AIA/SDO) time series in three channels: 304, 171, and 193 Å corresponding to the high chromosphere, transition region/low corona, and the corona, respectively. An established Time-Normalised Optical Flow method enhances the PD and applies a Lucas–Kanade algorithm to gain their velocity field. From the velocity field, we identify the source and sink locations of the PDs, and compare these locations between channels and with the underlying photospheric network. Source regions tend to be located above the photospheric network, and sink regions with the internetwork. Sink regions in the internetwork suggest either that closed field can be concentrated rather than evenly distributed in the internetwork, or that fieldlines opening into the corona can sometimes be concentrated above internetwork regions. We find regions of almost exact alignment between channels, and other regions where similar-shaped structures are offset by a few pixels between channels. These are readily interpreted as vertical or non-vertical alignment of the magnetic field relative to the observer viewing from above. Regions of isolated source regions in the cold (304 Å) or hotter (171 and 193 Å) channels can be interpreted in terms of the magnetic topology, but support for this is weaker. These results offer support for the future use of PD velocity fields as a coronal constraint on magnetic extrapolation models.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-025-02446-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Solar Ultraviolet Imaging Telescope on Board Aditya-L1","authors":"Durgesh Tripathi,&nbsp;A. N. Ramaprakash,&nbsp;Sreejith Padinhatteeri,&nbsp;Janmejoy Sarkar,&nbsp;Mahesh Burse,&nbsp;Anurag Tyagi,&nbsp;Ravi Kesharwani,&nbsp;Sakya Sinha,&nbsp;Bhushan Joshi,&nbsp;Rushikesh Deogaonkar,&nbsp;Soumya Roy,&nbsp;V. N. Nived,&nbsp;Rahul Gopalakrishnan,&nbsp;Akshay Kulkarni,&nbsp;Aafaque Khan,&nbsp;Avyarthana Ghosh,&nbsp;Chaitanya Rajarshi,&nbsp;Deepa Modi,&nbsp;Ghanshyam Kumar,&nbsp;Reena Yadav,&nbsp;Manoj Varma,&nbsp;Raja Bayanna,&nbsp;Pravin Chordia,&nbsp;Mintu Karmakar,&nbsp;Linn Abraham,&nbsp;H. N. Adithya,&nbsp;Abhijit Adoni,&nbsp;Gazi A. Ahmed,&nbsp;Dipankar Banerjee,&nbsp;B. S. Bhargava Ram,&nbsp;Rani Bhandare,&nbsp;Subhamoy Chatterjee,&nbsp;Kalpesh Chillal,&nbsp;Arjun Dey,&nbsp;Achim Gandorfer,&nbsp;Girish Gowda,&nbsp;T. R. Haridas,&nbsp;Anand Jain,&nbsp;Melvin James,&nbsp;R. P. Jayakumar,&nbsp;Evangeline Leeja Justin,&nbsp;K. Nagaraju,&nbsp;Deepak Kathait,&nbsp;Pravin Khodade,&nbsp;Mandeep Kiran,&nbsp;Abhay Kohok,&nbsp;Natalie Krivova,&nbsp;Nishank Kumar,&nbsp;Nidhi Mehandiratta,&nbsp;Vilas Mestry,&nbsp;Srikanth Motamarri,&nbsp;Sajjade F. Mustafa,&nbsp;Dibyendu Nandy,&nbsp;S. Narendra,&nbsp;Sonal Navle,&nbsp;Nashiket Parate,&nbsp;Anju M. Pillai,&nbsp;Sujit Punnadi,&nbsp;A. Rajendra,&nbsp;A. Ravi,&nbsp;Bijoy Raha,&nbsp;K. Sankarasubramanian,&nbsp;Ghulam Sarvar,&nbsp;Nigar Shaji,&nbsp;Nidhi Sharma,&nbsp;Aditya Singh,&nbsp;Shivam Singh,&nbsp;Sami K. Solanki,&nbsp;Vivek Subramanian,&nbsp;Rethika T,&nbsp;Srikanth T,&nbsp;Satyannarayana Thatimattala,&nbsp;Hari Krishna Tota,&nbsp;T. S. Vishnu,&nbsp;Amrita Unnikrishnan,&nbsp;Kaushal Vadodariya,&nbsp;D. R. Veeresha,&nbsp;R. Venkateswaran","doi":"10.1007/s11207-025-02423-1","DOIUrl":"10.1007/s11207-025-02423-1","url":null,"abstract":"<div><p>The Solar Ultraviolet Imaging Telescope (SUIT) is an instrument on the Aditya-L1 mission of the Indian Space Research Organization (ISRO) launched on 2 September 2023. SUIT continuously provides near-simultaneous full-disk and region-of-interest images of the Sun, slicing through the photosphere and chromosphere and covering a field of view up to 1.5 solar radii. For this purpose, SUIT uses 11 filters tuned at different wavelengths in the 200 – 400 nm range, including the Mg <span>ii</span> h and k and Ca <span>ii</span> H spectral lines. The observations made by SUIT help us understand the magnetic coupling of the lower and middle solar atmosphere. In addition, for the first time, this allows for the measurements of spatially resolved solar broad-band radiation in the near- and mid-ultraviolet, which will help constrain the variability of the solar ultraviolet irradiance in a wavelength range that is central for the chemistry of ozone and oxygen the Earth’s stratosphere. This paper discusses the details of the instrument and data products.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mysteries of the 17 May 2012 Solar Event Responsible for GLE71: II. Features of the Flare and Its Atypical Microwave Emission","authors":"V. V. Grechnev,&nbsp;V. I. Kiselev,&nbsp;A. M. Uralov,&nbsp;N. S. Meshalkina,&nbsp;A. L. Lysenko","doi":"10.1007/s11207-025-02437-9","DOIUrl":"10.1007/s11207-025-02437-9","url":null,"abstract":"<div><p>As known, large near-Earth proton enhancements usually occur after major eruptive solar flares accompanied by strong microwave bursts. Typically, the spectral-maximum frequency of such a burst exceeds 10 GHz, and the flux exceeds <span>(10^{4})</span> sfu. Ground-level cosmic-ray enhancements (GLEs) are the most energetic subset of large proton events, and it seems that microwave bursts in GLE-associated flares should follow this pattern. This is true in most cases, but in individual events that have produced GLEs, only moderate microwave bursts have been observed. In particular, in the SOL2012-05-17 event responsible for GLE71, the spectral-maximum frequency of the microwave burst did not exceed 10 GHz, and the flux did not reach <span>(10^{3})</span> sfu. We found that the temporal profile of the microwave burst followed the smoothed magnetic-reconnection rate, lagging behind it by about 50 s and that the burst properties were determined by the following circumstances: i) the magnetic configuration was asymmetric, and ii) the sources of the gyrosynchrotron emission were the entire flare arcade and a compact region above the sunspot umbra. Observations directly demonstrated these features, which were previously inferred for the SOL2001-12-26 event responsible for GLE63. A long-known discrepancy was observed between the estimates of the electron spectrum obtained from hard X-rays and microwaves. However, the hardening of the spectrum of trapped electrons that has been invoked to explain this discrepancy was not found in this event. Indications of a relationship between flare processes and proton acceleration are discussed.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neural-Based Compression for the Spectral Data of the New Vacuum Solar Telescope","authors":"Yan Dong,&nbsp;Zhenping Qiang,&nbsp;Jiayan Yang,&nbsp;Yunfang Cai,&nbsp;Qingyang Chen,&nbsp;Jia Cao","doi":"10.1007/s11207-025-02447-7","DOIUrl":"10.1007/s11207-025-02447-7","url":null,"abstract":"<div><p>Due to the rapid increase in spectral data generation as well as storage and transmission constraints, data compression has become particularly important for the New Vacuum Solar Telescope (NVST) at Yunnan Observatory. In this paper, we present a method for compressing NVST Ca II (8542 Å) spectral data based on a Convolutional Variational Autoencoder (VAE). Our results show that the compression ratios of the VAE-based approach may achieve as high as 107, while keeping the error between the decompressed data and the original data within the inherent error range of the raw data. This is much better than the appropriate compression ratio of 30 that is attained using the current PCA-based approach. Furthermore, the stability of the VAE approach is demonstrated by the almost constant differences between the VAE-compressed data and the raw data when the compression ratio ranges from 8 to 107. We also investigated Doppler velocity images deduced from the VAE-compressed data and found that the error in Doppler velocity is significantly less than 5 km s⁻¹ when the compression ratio does not exceed 107.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143564468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}