Solar Physics最新文献

{"title":"Characterizing High-Energy Solar Proton Events with Energies Below and Above 100 MeV","authors":"Dheyaa Ameri, Eino Valtonen, Amjad Al-Sawad, Rami Vainio","doi":"10.1007/s11207-024-02378-9","DOIUrl":"10.1007/s11207-024-02378-9","url":null,"abstract":"<div><p>We analyzed 58 high-energy proton events that occurred during the years 1996 – 2022. In 32 out of the 58 (55%) events, the proton energies extended up to <span>(sim 68)</span> MeV but did not reach 100 MeV. In the remaining 26 events, the proton energies exceeded 100 MeV. We studied the differences in the characteristics of these proton events and their associations with solar and interplanetary phenomena to improve understanding proton sources and acceleration processes.</p><p>The coronal mass ejections (CMEs) associated with <span>(>100)</span> MeV proton events appeared to be, on average, more energetic than those associated with <span>(< 100)</span> MeV proton events. The peak and integrated fluxes (fluence) of the soft X-ray (SXR) flares were higher in > 100 MeV proton events, but there was almost no difference in the rise times of the flares. In a major part of the <span>(> 100)</span> MeV proton events, protons were released over the rise phase of the SXR flares, whereas in most of the <span>(<100)</span> MeV events the proton releases occurred after the peak of the SXR flares. We established limits for the CME speed V<sub>CME</sub> and SXR peak flux F<sub>pk</sub> or total fluence F<sub><i>i</i></sub>, which helped us to distinguish the events in the two groups. Solar eruptions with V<sub>CME</sub> <span>(> 1000)</span> km s<sup>−1</sup> and F<span>(_{mathrm{pk}} > 5 cdot 10^{-5} )</span> W m<sup>−2</sup> had a high probability to produce proton events of <span>(> 100)</span> MeV. On the other hand, eruptions with V<span>(_{mathrm{CME}} > 900)</span> km s<sup>−1</sup> and F<span>(_{i} <5 cdot 10^{-4} )</span> J m<sup>−2</sup> and eruptions with V<span>(_{ mathrm{CME}} < 900)</span> km s<sup>−1</sup> irrespective of the SXR total fluence were very likely to produce proton events of <span>(< 100)</span> MeV.</p><p>All proton events were associated with decametric Type III radio bursts, and most of them had Type II bursts associations either in metric or decametric–hectometric (DH) wavelengths or both. Both metric- and DH-Type II emissions were observed in 50% of <span>(<100)</span> MeV proton events while they were observed in 88% of <span>(>100)</span> MeV events. Our analysis showed that protons in most of the <span>(>100)</span> MeV events were released low in the corona (<span>(leq 3.0)</span> R<sub>⊙</sub>) before the onsets of the DH-Type II radio bursts. Conversely, protons in most of the <span>(<100)</span> MeV events were released higher in the corona (<span>(>3)</span> R<sub>⊙</sub>) and after the DH-Type II onsets.</p><p>We conclude that protons in most of the <span>(> 100)</span> MeV events are accelerated either by the flare reconnection processes or by shocks low in the corona and could undergo reacceleration higher in the corona in CME shocks manifested in DH-Type II radio emission. In the <span>(<100)</span> MeV events, protons are mainly accelerated in CME sho","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02378-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413778","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":"Latitudinal Dependence of Variations in the Frequencies of Solar Oscillations Above the Acoustic Cut-Off","authors":"Laura Jade Millson,&nbsp;Anne-Marie Broomhall,&nbsp;Tishtrya Mehta","doi":"10.1007/s11207-024-02369-w","DOIUrl":"10.1007/s11207-024-02369-w","url":null,"abstract":"<div><p>At high frequencies beyond the acoustic cut-off, a peak-like structure is visible in the solar power spectrum. Known as the pseudo-modes, their frequencies have been shown to vary in anti-phase with solar magnetic activity. In this work, we determined temporal variations in these frequencies across the solar disc, with the aim of identifying any potential latitudinal dependence of pseudo-mode frequency shifts. We utilised nearly 22 years of spatially resolved GONG data for all azimuthal orders, <span>(textit{m})</span>, for harmonic degrees <span>(0leq lleq 200)</span>, and determined shifts using the resampled periodogram method. Periodogram realisations were created from overlapping, successive 216 day-long segments in time, and cropped to 5600 – 6800 μHz. Cross-correlation functions were then repeatedly generated between these realisations to identify any variation in frequency and the uncertainty. We categorised each mode by its latitudinal sensitivity and used this categorisation to produce average frequency shifts for different latitude bands (15^∘ and 5^∘ in size) which were compared to magnetic proxies, the <span>(F_{mathrm{10.7}})</span> index and GONG synoptic maps. Morphological differences in the pseudo-mode shifts between different latitudes were found, which were most pronounced during the rise to solar maximum where shifts reach their minimum values. At all latitudes, shift behaviour was strongly in anti-correlation with the activity proxy. Additionally, periodicities shorter than the 11-year cycle were observed. Wavelet analysis was used to identify a periodicity of four years at all latitudes.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02369-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413711","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 Spectro-Polarimeter of the Andrei B. Severny Solar Tower Telescope at the Crimean Astrophysical Observatory: Optical Design and Implementation","authors":"Alexander Kutsenko,&nbsp;Valery Terebizh,&nbsp;Andrei Dolgopolov,&nbsp;Valentina Abramenko,&nbsp;Andrei Plotnikov,&nbsp;Dmitriy Semyonov,&nbsp;Vladimir Skiruta,&nbsp;Vyacheslav Lopukhin","doi":"10.1007/s11207-024-02380-1","DOIUrl":"10.1007/s11207-024-02380-1","url":null,"abstract":"<div><p>The <i>Spectro-Polarimeter</i> (SP) is a new instrument installed at the upgraded <i>Andrei B. Severny Solar Tower Telescope</i> (STT) at the <i>Crimean Astrophysical Observatory</i>. The instrument is a traditional echelle slit dual-beam spectropolarimeter with temporal modulation of the polarization. STT-SP provides simultaneous spectropolarimetric observations of the Sun within three 15 Å wide spectral ranges around photospheric Fe I 5250 Å, Fe I 5324 Å, and chromospheric Mg I b2 5172 Å spectral lines. The spectral resolution of the instrument reaches 70,000 with the seeing-constrained slit width of 1 arcsec. The field-of-view of STT-SP is 200 arcsec allowing one to map a moderate size active region within a single raster scan. The instrument will provide new opportunities in the analysis of magnetic fields and thermodynamics of the lower atmosphere of the Sun. In this paper we describe the optical design of STT-SP and present the preliminary results acquired during the commissioning of the instrument.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413773","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":"A Linear Analysis of Torsional Alfvén Waves in Open Twisted Divergent Magnetic Flux Tubes for Coronal Heating","authors":"Bivek Pradhan,&nbsp;Gobinda Chandra Mishra,&nbsp;Pralay Kumar Karmakar,&nbsp;Utpal Deka","doi":"10.1007/s11207-024-02372-1","DOIUrl":"10.1007/s11207-024-02372-1","url":null,"abstract":"<div><p>The torsional Alfvén wave is highly regarded as the carrier of the energy from the photosphere to the corona in the solar atmosphere. This paper presents a comprehensive linear analysis of the wave behavior and energy transfer within an open, twisted, divergent magnetic flux tube configuration, considering the impact of wave guide structure on the propagation of these waves using the magneto-hydrodynamic approach. The study shows that waves with frequencies between 0.001 Hz and 1 Hz can effectively penetrate the transition region, with the most efficient energy transfer occurring in the 0.1 Hz to 1 Hz frequency range. The research findings suggest that waves with certain intermediate frequencies are able to transmit energy to the coronal region of the Sun, contributing to its active heating.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02372-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412781","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 Current State of the Controversy over Screening in Nuclear Reactions","authors":"Werner Däppen","doi":"10.1007/s11207-024-02377-w","DOIUrl":"10.1007/s11207-024-02377-w","url":null,"abstract":"<div><p>A controversy about the possibility of dynamic effects in nuclear screening has been around for several decades. On the one hand, there is the claim that there are no dynamic effects and that the classic Salpeter correction based on static Debye screening is all that is needed for astrophysical applications. The size of the correction is on the order of 5% in typical solar fusion reactions. On the other hand, numerical simulations have shown that there is a dynamical effect, which essentially cancels the Salpeter correction. The results of the numerical simulations were later independently confirmed. The astrophysical community, however, has so far largely ignored the possibility of dynamical screening. The present paper is meant to serve as a reminder of the controversy. Not only does the claim of an absence of a dynamical effect equally warrant an independent confirmation, but there is motivation for further investigation, such as the assessment of current laboratory experiments and a quantitative study of the dynamical effect in case it will turn out to be real.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412774","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":"Comparative Study of Solar Rotation of Transition Region and Corona using Solar Irradiance and Radio Flux","authors":"Avneesh Kumar,&nbsp;Nagendra Kumar,&nbsp;Hari Om Vats","doi":"10.1007/s11207-024-02375-y","DOIUrl":"10.1007/s11207-024-02375-y","url":null,"abstract":"<div><p>We study the temporal variation of solar rotation profiles based on solar irradiance at 93.5 nm and solar radio flux at 10.7 cm originating from the transition region and lower corona, respectively. The autocorrelation technique is used to calculate the period in periodic time series data. The sidereal rotation periods for normalized and detrended data are studied for 2011 – 2021. The sidereal rotation periods for solar irradiance and radio flux for 2011 – 2021 vary from 22.75 to 26.17 days and 19.42 to 28.14 days, respectively. The mean of the sidereal rotation periods for solar irradiance and radio flux are 24.76 and 23.76 days, respectively. The mean sidereal rotation period for solar irradiance is higher than the mean sidereal rotation period for solar radio flux. The sidereal rotation period for solar irradiance is greater than or equal to the sidereal rotation period for solar radio flux for almost all the years between 2011 and 2021. It is found that the lower corona rotates faster than the transition region during 2011 – 2021, i.e., the lower corona is found to be moving 4% faster than the transition region during 2011 – 2021. We found a linear relationship between the normalized daily irradiance and radio flux with a correlation coefficient of 0.986. Using cross-correlation analysis, we investigated a phase relationship between solar irradiance and radio flux and found no time lag between solar irradiance and radio flux.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412811","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. I. CME Development and the Role of Disturbances Excited by Eruptions","authors":"V. V. Grechnev,&nbsp;V. I. Kiselev,&nbsp;A. M. Uralov,&nbsp;N. S. Meshalkina,&nbsp;K. A. Firoz,&nbsp;A. L. Lysenko","doi":"10.1007/s11207-024-02373-0","DOIUrl":"10.1007/s11207-024-02373-0","url":null,"abstract":"<div><p>The SOL2012-05-17 event is remarkable in that it caused one of two ground-level enhancements (GLE71) in Solar Cycle 24. Despite the efforts spent studying this solar event, some aspects of it remain unclear. This relates to the development of a coronal mass ejection (CME), the history of the shock wave, and the flare. Our measurements reveal the following chain of phenomena. Two successive eruptions occurred within a few minutes. The rate of change of the reconnected magnetic flux shows a series of increases corresponding to the acceleration or deceleration of the erupting structures. The temporal profile of the magnetic-flux change rate is similar to the hard X-ray burst. Each eruption excited a disturbance that, propagating outward, accelerated all structures above it. This led to complex kinematic characteristics of the erupting structures that eventually formed a self-similarly expanding CME. The two disturbances became piston shocks and merged into a single, stronger shock. There are indications of transformation of the piston shock into a bow shock, but this occurs at distances exceeding ten solar radii. Components of the described picture were observed in a number of events and can serve as a guide for studies of eruptive flares.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412683","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":"The “SEP Clock”: A Discussion of First Proton Arrival Times in Wide-Spread Solar Energetic Particle Events","authors":"A. Posner,&nbsp;I. G. Richardson,&nbsp;R. D.-T. Strauss","doi":"10.1007/s11207-024-02350-7","DOIUrl":"10.1007/s11207-024-02350-7","url":null,"abstract":"<div><p>This work analyzes the appearance of wide-spread deka-MeV solar energetic proton (SEP) events, in particular the arrival of the first protons within ≈ 4.5 – 45 MeV measured at Earth–Sun L1, and their relationship with their relative solar source longitude. The definition of “wide-spread SEP event” for this study refers to events that are observed as a 25 MeV proton intensity increase at near 1 AU locations that are separated by at least 130^∘ in solar longitude. Many of these events are seen at all three of the spacecraft, STEREO (Solar-Terrestrial Relations Observatory) A, STEREO B, and SOHO (Solar and Heliospheric Observatory), and may therefore extend far beyond 130^∘ in longitude around the Sun. A large subset of these events have already been part of a study by Richardson et al. (<i>Solar Phys</i>., <b>289</b>, 3059, 2014). The event source region identifications draw from this study; more recent events have also been added. Our focus is on answering two specific questions: (1) What is the maximum longitude over which SEP protons show energy dispersion, i.e., a clear sign of arrival of higher-energy protons before those of lower energy? (2) What implications can be drawn from the ensemble of events observed regarding either direct magnetic connectivity to shocks and/or cross-field transport from the site of the eruption in the onset phase of the event?</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02350-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412773","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":"Online Catalog of Activity Events of Solar Cycle 24 Related to Active Regions","authors":"Tsvetan Tsvetkov,&nbsp;Yoana Nakeva,&nbsp;Nikola Petrov","doi":"10.1007/s11207-024-02351-6","DOIUrl":"10.1007/s11207-024-02351-6","url":null,"abstract":"<div><p>We present a statistical study on the relationship of solar dynamic events (solar flares and coronal mass ejections) with active regions during Solar Cycle 24 (December 2008–December 2019). Combining data from NOAA Space Weather Prediction Center and observations of Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft, we found that more than a half of the coronal mass ejections were generated inside active regions. Geostationary Operational Environmental Satellite (GOES) soft X-ray flare listing data completed our study showing that almost 83% of Solar Cycle 24 flares are connected with active regions. Finally, we summarize the details for the related phenomena into an online catalog based on a list of all 1533 active regions that produced at least one flare and/or coronal mass ejection during Solar Cycle 24 and explore their properties like flare class, coronal mass ejection speed, and angular width paying special attention to the most powerful and threatful to Earth solar events.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412601","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":"Is There a Synchronizing Influence of Planets on Solar and Stellar Cyclic Activity?","authors":"V. N. Obridko,&nbsp;M. M. Katsova,&nbsp;D. D. Sokoloff,&nbsp;N. V. Emelianov","doi":"10.1007/s11207-024-02365-0","DOIUrl":"10.1007/s11207-024-02365-0","url":null,"abstract":"<div><p>This work continues our research of the connection between the long-term activity of stars and their planets. We analyze new data on the previously considered two dozen solar-type stars with identified cycles, adding the results of studying the long-term variability of two more solar-type G stars and 15 cooler M dwarfs with planets. If the cyclic activity is determined by a strong tidal influence of the planet, then the cycle duration of the star should be synchronized with the period of orbital revolution of the planet. We calculate the gravitational effect of planets on their parent stars. The results obtained confirm the earlier conclusion that exoplanets do not influence the formation of the stellar cycle. We examine the change in the position of the barycenter of the solar system relative to the center of the Sun over 420 years. A comparison of these data with the most reliable 120-year SSN (sunspot number) series as the index of solar activity has shown that they are not synchronized.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219147","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}