Solar Physics最新文献

{"title":"Improved Tomographic Reconstruction of 3D Global Coronal Density from STEREO/COR1 Observations","authors":"Tongjiang Wang,&nbsp;C. Nick Arge,&nbsp;Shaela I. Jones","doi":"10.1007/s11207-025-02454-8","DOIUrl":"10.1007/s11207-025-02454-8","url":null,"abstract":"<div><p>Tomography is a powerful technique for recovering the three-dimensional (3D) density structure of the global solar corona. In this work, we present an improved tomography method by introducing radial weighting in the regularization term. Radial weighting provides balanced smoothing of density values across different heights, helping to recover finer structures at lower heights while also stabilizing the solution and preventing oscillatory artifacts at higher altitudes. We apply this technique to reconstruct the 3D electron density of Carrington Rotation (CR) 2098 using two weeks of polarized brightness (pB) observations from the inner coronagraph (COR1) on board spacecraft-B of the twin Solar Terrestrial Relations Observatory (STEREO), where the radial weighting function is taken as the inverse intensity background, calculated by averaging all the pB images used. Comparisons between density distributions at various heights from the tomography and magnetohydrodynamics (MHD) simulations show good agreement. We find that radial weighting not only effectively corrects the oversmoothing effect near the inner boundary in reconstructions using second-order smoothing but also significantly improves reconstruction quality when using zero-order smoothing. Additionally, comparing reconstructions for CR 2091 from single-satellite data with that from multiviewpoint data suggests that coronal evolution and dynamics may significantly impact on the reconstructed density structures. This improved tomography method has been used to create a database of 3D densities for CRs 2052 to 2154, based on STEREO/COR1-B data, covering the period from 08 January 2007 to 17 September 2014.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761772","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":"Turbulence Evolution Between 0.5 and 1 AU for the Solar Wind of Various Origins","authors":"Liudmila Rakhmanova,&nbsp;Maria Riazantseva,&nbsp;Yuri Yermolaev,&nbsp;Alexander Khokhlachev,&nbsp;Georgy Zastenker","doi":"10.1007/s11207-025-02458-4","DOIUrl":"10.1007/s11207-025-02458-4","url":null,"abstract":"<div><p>Probing the solar wind at different distances from the Sun provides a great opportunity to explore turbulence development in the unlimited space. Recent measurements from the near-Sun plasma demonstrate the evolution of turbulence from an undeveloped to a fully developed state on the path from the Sun to the Earth. On the other hand, the properties of turbulence are known to be altered for the solar-wind streams of different origin. The present study adopts measurements during two Solar Orbiter and Wind alignments with separations of 0.1 and 0.5 AU to analyze changes in the properties of turbulence for the same plasma parcels embedded in the solar-wind streams of various origins. The results demonstrate that at scales spectra become shallower toward the Earth’s orbit, while Kolmogorov scaling stays unchanged at the MHD scales. The power of the fluctuations within the inertial range is shown to be an important factor that determines the evolution of the turbulent fluctuations in the inner heliosphere, regardless of the origin of the solar-wind stream.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761707","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 Study on the Transition-Range Spectral Index of the Solar Wind Turbulence in the Inner Heliosphere","authors":"Haifeng Yang,&nbsp;Guoqing Zhao,&nbsp;Hengqiang Feng,&nbsp;Liang Xiang","doi":"10.1007/s11207-025-02439-7","DOIUrl":"10.1007/s11207-025-02439-7","url":null,"abstract":"<div><p>Based on observations from Parker Solar Probe, this paper studies the dependence of the correlations between the transition-range spectral index of the magnetic energy spectrum and four parameters (inertial-range cross-helicity and magnetic energy density, transition-range magnetic helicity, and bulk proton temperature) on solar wind speed and heliocentric distance. Results show significant correlations between the spectral index and both cross-helicity and magnetic energy density. Notably, at lower speeds or closer distances, the correlation coefficient (CC) between the cross-helicity and spectral index is smaller than that between the magnetic energy density and spectral index. Conversely, at higher speeds or greater distances, the correlation with cross-helicity becomes comparable to or even exceeds that with magnetic energy density. Additionally, as the speed increases or the heliocentric distance decreases, cross-helicity, magnetic energy density, proton temperature, and the absolute values of the spectral index show a mostly upward trend. Moreover, cross-helicity, absolute values of the spectral index, and CC between the magnetic energy density and spectral index exhibit a similar trend with the speed, initially rising and then declining at the highest speed bin. We discuss the results using the recently proposed “helicity barrier” effect.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761709","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":"Coronal Electric Currents and Kink Instability of Magnetic Flux Rope","authors":"Yuriy T. Tsap,&nbsp;Alexander V. Stepanov,&nbsp;Yulia G. Kopylova","doi":"10.1007/s11207-025-02461-9","DOIUrl":"10.1007/s11207-025-02461-9","url":null,"abstract":"<div><p>Using the energy method and the thin magnetic flux tube approximation, we find the wave dispersion relation for magnetohydrodynamic kink oscillations of a force-free magnetic flux rope with uncompensated longitudinal electric current under solar coronal conditions. The eigenvectors are shown to impose restrictions on the conditions of the kink instability of a flux rope. The observed weak twist of coronal loops with a small (<span>(lesssim 1)</span>) number of turns of the magnetic field lines around the axis indicates the dominance of unshielded magnetic flux ropes in the corona of the Sun, in which the longitudinal electric currents do not exceed <span>(10^{11})</span> – <span>(10^{12})</span> A. These restrictions can be associated with the absence of solar superflares. The period of kink oscillations of twisted coronal loops should decrease with decreasing longitudinal electric current, which can be used to study its dynamics in solar flares. No dependence of compact and eruptive solar flares on the twist of flux ropes can be explained by the coexistence of both shielded and unshielded electric currents in the corona.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761706","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":"Turbulent Power: A Discriminator Between Sheaths and CMEs","authors":"Deep Ghuge,&nbsp;Debesh Bhattacharjee,&nbsp;Prasad Subramanian","doi":"10.1007/s11207-025-02457-5","DOIUrl":"10.1007/s11207-025-02457-5","url":null,"abstract":"<div><p>Solar coronal mass ejections (CMEs) directed at the Earth often drive large geomagnetic storms. Here, we use velocity, magnetic field, and proton density data from 152 CMEs that were sampled in situ at 1 AU by the Wind spacecraft. We Fourier analyze fluctuations of these quantities in the quiescent pre-CME solar wind, sheath, and magnetic cloud. We quantify the extent by which the power in turbulent (magnetic field, velocity, and density) fluctuations in the sheath exceeds that in the solar wind background and in the magnetic cloud. For instance, the mean value of the power per unit volume in magnetic field fluctuations in the sheath is 76.7 times that in the solar wind background, while the mean value of the power per unit mass in velocity fluctuations in the sheath is 9 times that in the magnetic cloud. Our detailed results show that the turbulent fluctuation power is a useful discriminator between the ambient solar wind background, sheaths, and magnetic clouds and can serve as an input for space weather prediction.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761710","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":"Investigating Solar Wind Outflows from Open–Closed Magnetic Field Structures Using Coordinated Solar Orbiter and Hinode Observations","authors":"Nawin Ngampoopun,&nbsp;Roberto Susino,&nbsp;David H. Brooks,&nbsp;Roberto Lionello,&nbsp;Lucia Abbo,&nbsp;Daniele Spadaro,&nbsp;Deborah Baker,&nbsp;Lucie M. Green,&nbsp;David M. Long,&nbsp;Stephanie L. Yardley,&nbsp;Alexander W. James,&nbsp;Marco Romoli,&nbsp;Silvio M. Giordano,&nbsp;Aleksandr Burtovoi,&nbsp;Federico Landini,&nbsp;Giuliana Russano","doi":"10.1007/s11207-025-02438-8","DOIUrl":"10.1007/s11207-025-02438-8","url":null,"abstract":"<div><p>ESA/NASA’s Solar Orbiter (SO) enables us to study the solar corona at closer distances and from different perspectives, which helps us to gain significant insights into the origin of the solar wind. In this work, we present the analysis of solar wind outflows from two locations: a narrow open-field corridor and a small, mid-latitude coronal hole. These outflows were observed off-limb by the Metis coronagraph onboard SO and on-disk by the Extreme Ultraviolet Imaging Spectrometer (EIS) onboard Hinode. Magnetic field extrapolations suggest that the upflow regions seen in EIS were the sources of the outflowing solar wind observed with Metis. We find that the plasma associated with the narrow open-field corridor has higher electron densities and lower outflow velocities compared to the coronal hole plasma in the middle corona, even though the plasma properties of the two source regions in the low corona are found to be relatively similar. The speed of the solar wind from the open-field corridor also shows no correlation with the magnetic field expansion factor, unlike the coronal hole. These pronounced differences at higher altitudes may arise from the dynamic nature of the low-middle corona, in which reconnection can readily occur and may play an important role in driving solar wind variability.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-025-02438-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761708","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":"Transverse Oscillations in Thin Magnetic Tubes with Elliptical Cross-Sections: The Effect of Field Aligned Flow","authors":"Igor Lopin","doi":"10.1007/s11207-025-02460-w","DOIUrl":"10.1007/s11207-025-02460-w","url":null,"abstract":"<div><p>The effect of longitudinal plasma flow on transverse oscillations in the thin magnetic tubes with elliptical cross-sections is examined. The backward propagating waves of the <span>(M)</span>-kink mode (polarized along the major axis) and <span>(m)</span>-kink mode (polarized along the minor axis) are found to reverse their propagation direction at certain flow thresholds. The critical flow for the <span>(M)</span>-kink mode is lower than in a circular tube and is close to the internal Alfvén speed. This result is of particular interest within the concept of existence of negative energy waves in solar waveguides. Both modes are subjected to the Kelvin–Helmholtz (KH) instability, and the <span>(M)</span>-mode is more stable than the <span>(m)</span>-mode. Magnetic tubes with significant ellipticity are more resistant to the KH instability than circular tubes. In the quasi-standing wave regime, the frequencies of both modes decrease and the frequency ratio <span>(omega _{m}/omega _{M})</span> increases with faster flows. The obtained results are used to interpret the observed transverse oscillations of the solar limb spicules and their helical motions in terms of the <span>(M)</span>- and <span>(m)</span>-kink modes.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749170","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 New Implementation of a Fourth-Order CESE Scheme for 3D MHD Simulations","authors":"Chaowei Jiang,&nbsp;Ling Zhang","doi":"10.1007/s11207-025-02452-w","DOIUrl":"10.1007/s11207-025-02452-w","url":null,"abstract":"<div><p>This paper is devoted to the description and validation of a new implementation of a fourth-order space–time conservation-element and solution-element (CESE) scheme to numerically solve the time-dependent, three-dimensional (3D) magnetohydrodynamic (MHD) equations. The core of the scheme is that, with the aid of a grid staggered in space and time, the conservative variables are advanced by integration of the controlling equation in the space–time four-dimensional domain by utilizing Taylor expansion, and their spatial derivatives are computed by finite difference with <span>(p)</span> order derivatives from <span>(p-1)</span> order ones. The new scheme achieves fourth-order accuracy in both space and time simultaneously, using a compact stencil identical to that in the second-order CESE scheme. We provide a general framework for convenience of programming such that the scheme can be easily extended to arbitrarily higher order by including higher-order terms in the Taylor series. A suite of 3D MHD tests demonstrate that the fourth-order CESE scheme at relatively low grid resolutions can obtain reliable solution comparable to the second-order CESE scheme at four-times higher resolution, and showing a very high efficiency in computing by using only around <span>(5%)</span> of the computing resources.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716806","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":"Arecibo Multifrequency IPS Observations: Solar-Wind Density Turbulence Scale Sizes and Their Anisotropy","authors":"P. K. Manoharan,&nbsp;C. J. Salter","doi":"10.1007/s11207-025-02445-9","DOIUrl":"10.1007/s11207-025-02445-9","url":null,"abstract":"<div><p>We present an analysis of interplanetary scintillation (IPS) observations conducted with the Arecibo 305-m radio telescope during the minimum phase at the end of Solar Cycle 24 and the onset of Solar Cycle 25. These observations span a broad frequency range of ∼ 300 to 3100 MHz, encompassing the P-, L-, and S-bands, and cover heliocentric distances from ∼ 5 to 200 solar radii. Each L-band observation provided simultaneous measurements across a bandwidth of approximately 600 MHz. Furthermore, whenever feasible, the near-simultaneous measurements of a source acquired across all three frequency bands were useful to study the scintillation characteristics over a much wider frequency band along the same line of sight through the heliosphere. The dynamic spectrum of the scintillations obtained at the L-band shows a systematic decrease in the scintillation index from the lowest to the highest frequency, offering valuable insight into the influence of the solar wind density microstructures responsible for scintillation. Analyses of the scintillation index (<span>(m)</span>) for multiple sources at the L-band, along with near-simultaneous observations of selected sources covering the P-, L-, and S-bands, clearly demonstrate a wavelength dependence of <span>(m propto lambda ^{omega })</span>, which inherently leads to a dependence of <span>(m)</span> on the Fresnel scale, when considering the effective distance to the scattering screen, <span>(z)</span>. The index <span>(omega )</span> ranges between ∼ 1 and 1.8. The average <span>(omega )</span> value of a source, determined from observations made on multiple days (i.e., at a range of solar offsets to mitigate the influence of possible day-to-day variations in solar-wind turbulence) exhibits variability across sources. The results on the radial dependence of scintillation agree with earlier IPS measurements. The temporal power spectra obtained over the wide frequency range exhibit a power-level evolution in accordance with the wavelength dependence and a broadening with an increasing observation frequency. Furthermore, the increased temporal–frequency rounding of the “Fresnel knee” in the spectrum with the observing frequency suggests a novel phenomenon: an increase in anisotropy as the scale size of the density–turbulence structure decreases.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716809","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":"Influence of the Deformation of Coronal Mass Ejections on Their in-Situ Fitting with Circular-Cross-Section Flux Rope Models","authors":"Bin Zhuang,&nbsp;Noé Lugaz,&nbsp;Nada Al-Haddad,&nbsp;Charles J. Farrugia,&nbsp;Ute Amerstorfer,&nbsp;Emma E. Davies,&nbsp;Manuela Temmer,&nbsp;Hannah T. Rüdisser,&nbsp;Wenyuan Yu,&nbsp;Tingyu Gou,&nbsp;Réka M. Winslow","doi":"10.1007/s11207-025-02444-w","DOIUrl":"10.1007/s11207-025-02444-w","url":null,"abstract":"<div><p>Understanding the properties, especially the magnetohydrodynamic (MHD) invariants, of coronal mass ejections (CMEs) measured in-situ is key to bridging the CME properties from the Sun to interplanetary space. In order to investigate CMEs based on in-situ measurements that provide a one-dimensional (1D) cut of the CME parameters over the spacecraft trajectory, various magnetic flux rope (MFR) models have been developed, among which the models with a circular cross section are the most popular and widely used. CMEs are found to be deformed during their propagation in interplanetary space, in which the cross section may be flattened in the direction of propagation, leading to the development of an elliptical or even pancake-like shape. We use numerical MHD simulations in 2.5D to investigate the influence of the CME deformation on the in-situ fitting using two linear force-free MFR models with a circular cross section, and we focus on the axial and poloidal magnetic fluxes, which are conserved in the ideal MHD frame. We quantitatively compare the fitted axial and poloidal fluxes with those in the simulations. We find that both models underestimate the axial flux compared to that in the simulations and that such underestimations depend on the CME deformation. However, the fitting of the poloidal flux is independent of the deformation. We discuss the reasons for the axial flux underestimation and the implication of the CME deformation for the CME in-situ fitting.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"300 4","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707131","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}