Astrophysics and Space Science最新文献_第5页

Characterizing the Stannern-trend eucrite Berthoud: micro-Raman, FTIR, XRD, EDXRF, and petrographic approach 斯坦纳倾向白绿晶的表征：微观拉曼、FTIR、XRD、EDXRF和岩石学方法

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-28 DOI: 10.1007/s10509-026-04610-3

Ozan Unsalan, Irmak Ayvaz, Ceren Ertatis, Cisem Altunayar-Unsalan, Michael E. Zolensky, Osman Candan, Ceren Kamil

{"title":"Characterizing the Stannern-trend eucrite Berthoud: micro-Raman, FTIR, XRD, EDXRF, and petrographic approach","authors":"Ozan Unsalan, Irmak Ayvaz, Ceren Ertatis, Cisem Altunayar-Unsalan, Michael E. Zolensky, Osman Candan, Ceren Kamil","doi":"10.1007/s10509-026-04610-3","DOIUrl":"10.1007/s10509-026-04610-3","url":null,"abstract":"<div><p>This study aims to address the mineralogical and compositional complexities of the HED meteorite clan, which is thought to have originated from the regolith of asteroid 4 Vesta, and which is characterized by a diverse assemblage of igneous minerals, including olivine, pyroxene (orthopyroxene and clinopyroxene), and plagioclase, reflecting the intricate geologic history of its parent body. While the HED meteorites have been extensively studied, detailed investigations into the mineralogical composition of the Berthoud eucrite (sample BRT-01) are still required. This research endeavours to bridge this knowledge gap by employing advanced analytical techniques-micro-Raman spectroscopy, energy-dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and petrography-to provide a comprehensive characterization of BRT-01. Through the identification and quantification of its mineral phases, this study contributes to a more nuanced understanding of the petrological and geochemical evolution of the HED parent body and the processes governing the formation of 4 Vesta’s regolith. Micro-Raman spectroscopy of selected plagioclase-rich domains indicates an anorthite-rich composition close to An85, whereas XRD and EDXRF results suggest that the bulk sample contains multiple plagioclase phases and/or compositionally heterogeneous plagioclase domains. Our integrated approach not only characterizes the mineralogy and compositional phases of Berthoud but also provides evidence supporting its classification within the Stannern trend, contributes to its deformation history and to broader understanding of crustal evolution processes on asteroid 4 Vesta.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

The Roche-lobe radius in Newtonian and non-Newtonian gravity 牛顿和非牛顿引力中的罗氏叶半径

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-28 DOI: 10.1007/s10509-026-04611-2

A. M. Velásquez-Toribio

引用次数: 0

Optical monitoring and variability analysis of the blazar 1ES 0806+524 耀变体1ES 0806+524的光学监测与变异性分析

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-28 DOI: 10.1007/s10509-026-04609-w

W. X. Liu, Q. Z. Zhang, Y. H. Yuan

{"title":"Optical monitoring and variability analysis of the blazar 1ES 0806+524","authors":"W. X. Liu, Q. Z. Zhang, Y. H. Yuan","doi":"10.1007/s10509-026-04609-w","DOIUrl":"10.1007/s10509-026-04609-w","url":null,"abstract":"<div><p>We present optical monitoring of the BL Lac object 1ES 0806+524 using the 1.26 m National Astronomical Observatory-Guangzhou University Infrared/Optical telescope (NGT) on 13 nights from 22 February to 1 October 2023. We use several methods to analyse the intraday optical variability (IDV), reporting a faint IDV result on one night, and find a maximum magnitude variation of 0.101 ± 0.045 in 35.583 minutes. We analyse the relation between spectral indices (<span>(alpha )</span>) and flux densities (<span>(F_{mathit{gri}})</span>) on several timescales. On a short-term timescale, the linear correlation between spectral indices and flux densities is weak. A redder-when-brighter (RWB) trend is observed in the <span>(mathit{i})</span> band on an intraday timescale, differing from the typical bluer-when-brighter (BWB) behaviour reported in previous long-term studies. Furthermore, we find complex behaviour, including clockwise and anticlockwise loops, possibly related to electron acceleration and cooling processes in the jet. Time evolution of colour is found on one night, which may be caused by magnetic reconnection. These results provide new insights into the emission from the jet of 1ES 0806+524 in the optical regime.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

A statistical analysis of total solar eclipses’ influence on magnetospheric complexity 日全食对磁层复杂性影响的统计分析

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-28 DOI: 10.1007/s10509-026-04607-y

Sajith Babu S, K. Unnikrishnan

{"title":"A statistical analysis of total solar eclipses’ influence on magnetospheric complexity","authors":"Sajith Babu S, K. Unnikrishnan","doi":"10.1007/s10509-026-04607-y","DOIUrl":"10.1007/s10509-026-04607-y","url":null,"abstract":"<div><p>As evident from previous studies, the reduction in ionization of the E layer during total solar eclipse influences the geomagnetic field effects. We have investigated eclipse-induced variations in the complex behaviour of the magnetosphere, by studying 8 total solar eclipse events from 1997 to 2019. The effect of modulations in the geomagnetic field due to solar eclipse is reflected in the complex behaviour of magnetosphere, and these effects are studied using different dynamical complexity measures, namely: Tsallis entropy, Renyi entropy, Hurst exponent, Beta exponent, and Fractal dimension. The geomagnetic field component data recorded by the magnetic observatories (MOs) located close to the place of occurrence of the greatest eclipse, are used to analyse the eclipse effect on the magnetospheric complexity. Analysis of both the daily average and eclipse hour average values of the horizontal component of geomagnetic field (H component) revealed that, the eclipse induced change on H component was relatively small. Out of the 12 magnetic observatories (MOs) that we used for this study, data from 11 MOs have shown a minimal increase in the daily average value of the H component in different magnitudes. The average values of Tsallis and Renyi entropies showed an increase during the eclipse period, indicating an increase in the magnetospheric complexity close to the totality path of eclipse; but these changes are not abnormal. The variations in the Hurst exponent, Beta exponent, and Fractal dimension values during the eclipse period can be interpreted as the system’s departure from its stable state during the eclipse period.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

Global (m=1) bending instabilities in radially hot galactic discs 径向热星系盘的全局(m=1)弯曲不稳定性

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-22 DOI: 10.1007/s10509-026-04606-z

Sagar S. Goyary

{"title":"Global (m=1) bending instabilities in radially hot galactic discs","authors":"Sagar S. Goyary","doi":"10.1007/s10509-026-04606-z","DOIUrl":"10.1007/s10509-026-04606-z","url":null,"abstract":"<div><p>We investigate the global <span>(m=1)</span> bending mode instability in radially hot, Milky Way-like galactic discs using a linear perturbation framework. Our analysis shows that radial heating plays a key role in driving the instability: as the Toomre parameter <span>(Q)</span> increases, the disc becomes progressively more susceptible to bending instability, accompanied by a systematic decrease in the growth timescale of the unstable <span>(m=1)</span> mode. This behaviour reflects the enhanced in-plane random motions that weaken the effective restoring forces and facilitate the growth of bending modes. We further demonstrate that the dark matter halo significantly influences the stability properties of the disc, with low-mass halo systems supporting a larger number of unstable modes, while more massive halos enhance the vertical restoring force and suppress bending instabilities, leading to slower growth of the <span>(m=1)</span> mode. Our results suggest that radially hot discs are inherently prone to global <span>(m=1)</span> bending instabilities even in isolation, whereas massive dark matter halos act to stabilize the disc against such vertical distortions.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

Optical colour variability and inter-band timing of the HSP blazar 4FGL J0540.5+5823 with ZTF HSP耀变体4FGL J0540.5+5823与ZTF的光学颜色变化和带间时序

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-17 DOI: 10.1007/s10509-026-04603-2

Xiao-Pan Li, Haitao Yang, Rong Rong, Taimin Yuan

{"title":"Optical colour variability and inter-band timing of the HSP blazar 4FGL J0540.5+5823 with ZTF","authors":"Xiao-Pan Li, Haitao Yang, Rong Rong, Taimin Yuan","doi":"10.1007/s10509-026-04603-2","DOIUrl":"10.1007/s10509-026-04603-2","url":null,"abstract":"<div><p>Optical colour variability and inter-band timing probe synchrotron evolution in blazar jets, but survey cadence can bias colour–magnitude trends and apparent lags when multi-band sampling is non-simultaneous and interrupted by seasonal gaps. We analyse Zwicky Transient Facility (ZTF) <span>(g)</span>- and <span>(r)</span>-band photometry of the high-synchrotron-peaked blazar 4FGL J0540.5+5823. Quasi-simultaneous colours are constructed by nearest-neighbour pairing within <span>(Delta t_{max }=0.03-0.05)</span> d, and two-band activity episodes are defined objectively via Bayesian Blocks restricted to the <span>(g/r)</span> overlap. Colour–magnitude slopes are measured with robust regression, and their significance is assessed with a season-wise block-permutation test to account for clustered cadence. Inter-band delays are estimated with the z-transformed discrete correlation function (ZDCF) and, for the three best-sampled episodes, with flare peak-time offsets from asymmetric envelope fits. We find a persistent bluer-when-brighter trend (<span>(b=0.063pm 0.013)</span> for <span>(Delta t_{max }=0.05)</span> d) with sampling-aware significance <span>(p_{mathrm{block}}=6.3times 10^{-3})</span>. The global ZDCF prefers a positive lag of order 10 d but with broad uncertainty, while episode-level ZDCF lags are consistent with zero; envelope fits reveal one episode with an <span>(r)</span>-leading peak offset of <span>(8.2pm 2.2)</span> d. The coexistence of a stable baseline colour trend with episode-dependent timing behaviour favours band-dependent profile evolution rather than a rigid inter-band delay, motivating denser multi-band and polarimetric follow-up.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

New analytic solutions with thrust tangential or perpendicular to the flight direction: a class of generalized parabolas 推力与飞行方向相切或垂直的新解析解：一类广义抛物线

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-14 DOI: 10.1007/s10509-026-04604-1

Eric Guiot

引用次数: 0

Artificial Neural Network–based prediction of D-region electron density variations during solar flares using ground-based VLF observations over low-latitude Indian region 基于人工神经网络的低纬度印度地区地面VLF观测预测太阳耀斑期间d区电子密度变化

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-07 DOI: 10.1007/s10509-026-04602-3

Shivani Chandra, Sudipta Sasmal, Abhirup Datta, Rajesh Singh, Sampad Kumar Panda, Yasuhide Hobara, Ajeet K. Maurya

{"title":"Artificial Neural Network–based prediction of D-region electron density variations during solar flares using ground-based VLF observations over low-latitude Indian region","authors":"Shivani Chandra, Sudipta Sasmal, Abhirup Datta, Rajesh Singh, Sampad Kumar Panda, Yasuhide Hobara, Ajeet K. Maurya","doi":"10.1007/s10509-026-04602-3","DOIUrl":"10.1007/s10509-026-04602-3","url":null,"abstract":"<div><p>The ionospheric D-region (60–90 km) critically controls very low frequency (VLF) radio wave propagation and responds rapidly to solar flare radiation. Accurate prediction of D-region electron density is therefore essential for reliable space weather nowcasting. We develop an artificial neural network (ANN) framework to predict flare-induced electron density enhancements using ground-based VLF observations from Dehradun and Indore, India (2020–2025). A total of 244 solar flares (157 C-class, 87 M-class) were analyzed. Seven physically motivated inputs: time of day, day of year, VLF amplitude perturbation, reflection height (H′), sharpness factor (<span>(beta )</span>), F10.7 flux, and GOES X-ray flux were used to train a feed-forward backpropagation network. The model achieved excellent skill for C-class flares (R = 0.98; MSE = 8.735 × 10<sup>−5</sup>; RMSE = 0.0295; and MAE = 0.0182) and moderate performance for M-class flares (R = 0.74; MSE = 4.06 × 10<sup>−1</sup>; RMSE = 0.63; MAE = 0.47), reflecting increased ionospheric variability under stronger solar forcing. These results demonstrate the robustness of ANN-based approaches for real-time D-region electron density estimation and operational space weather forecasting.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148389076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

An effective double-layer stellar structure 一个有效的双层恒星结构

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-30 DOI: 10.1007/s10509-026-04601-4

K. Campos, J. Andrade, O. F. Bustos, D. Santana, C. Usca

引用次数: 0

Imaging black holes: a VLBI success story 黑洞成像：VLBI的成功案例。

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-30 DOI: 10.1007/s10509-026-04598-w

J. Anton Zensus

{"title":"Imaging black holes: a VLBI success story","authors":"J. Anton Zensus","doi":"10.1007/s10509-026-04598-w","DOIUrl":"10.1007/s10509-026-04598-w","url":null,"abstract":"<div><p>Advances in Very Long Baseline Interferometry (VLBI) have enabled, for the first time, horizon-scale images of the two most accessible supermassive black hole candidates: M87* at the centre of the elliptical galaxy Messier 87 and Sgr A* at the centre of the Milky Way. These images reveal ring-like emission surrounding central brightness depressions whose angular sizes are consistent with the black-hole signatures predicted by general relativity. The theoretical framework and early predictions of observable black hole signatures, developed from the 1970s onward, established the scientific motivation and defined the instrumental requirements for this endeavour. Achieving the required angular resolution and sensitivity demanded transformational enhancements to existing VLBI arrays, pursued along two complementary paths: space VLBI, extending baselines beyond the Earth, and mm-VLBI, observing at the shortest accessible radio wavelengths from the ground. The latter strategy, realised through the addition of the Atacama Large Millimeter Array to a global network of mm-wavelength telescopes, advances in receiver technology, data processing, and image reconstruction methods, and the formation of an international collaboration, yielded the first images of the predicted black hole shadows. This established the observational foundation for a broad programme of follow-up studies.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 6","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13320083/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148374342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0