Astrophysics and Space Science最新文献

A study on star formation in rotating and magnetized filamentary molecular clouds 旋转磁化丝状分子云中恒星形成的研究

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-12 DOI: 10.1007/s10509-026-04653-6

Ashok Mondal

引用次数: 0

Error analysis of ionospheric VTEC inversion over China via a single-parameter directional perturbation method 中国电离层VTEC反演的单参数定向摄动误差分析

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-08 DOI: 10.1007/s10509-026-04644-7

Fuying Zhu, Chao Xiong, Jian Lin

{"title":"Error analysis of ionospheric VTEC inversion over China via a single-parameter directional perturbation method","authors":"Fuying Zhu, Chao Xiong, Jian Lin","doi":"10.1007/s10509-026-04644-7","DOIUrl":"10.1007/s10509-026-04644-7","url":null,"abstract":"<div><p>Disentangling individual error sources in regional ionospheric modeling remains difficult because multiple uncertainties are strongly coupled during the Vertical Total Electron Content (VTEC) inversion. To address this issue, we develop a single-parameter directional perturbation framework and apply it to GNSS observations from more than 250 stations of the Crustal Movement Observation Network of China (CMONOC), with the aim of identifying and quantifying the dominant drivers of inversion error. The results show that phase-smoothed pseudorange (P<sub>4</sub>) noise and elevation mask angle (EMA) dictate inversion stability, revealing a critical trade-off between low-elevation noise suppression and spatial coverage. Specifically, increasing P<sub>4</sub> noise (0.1 to 0.5 m) escalates the Mean Absolute Error (MAE) from 0.88 to 5.66 TECu (1 TECu = 10<sup>16</sup> el⋅m<sup>−2</sup>), while raising the EMA (20° to 30°) increases the MAE from 0.44 to 1.05 TECu. Furthermore, the Spherical Harmonic Order (SHO) exhibits a non-linear impact: the K=M=8 configuration is optimal, whereas over-parameterization (K=M=10) triggers severe boundary oscillations, driving the MAE up to 19.45 TECu under weak observation geometry. Our results also indicate a strong environmental dependence of systematic biases. In the low-TEC morning sector (06:00–08:00 LT), Differential Code Bias (DCB) perturbations inflate the MAPE to 24.85%, and this sensitivity is further amplified during geomagnetic disturbances, causing a significant drop in inversion accuracy (MAE=0.60 TECu). Under these same conditions, the optimized high-order SH scheme proves its robustness, maintaining an MAE of only 0.08 TECu. These results provide a quantitative assessment of the error budget in regional VTEC inversion and offer practical benchmarks for improving regional ionospheric modeling under different space weather conditions.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 10","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149133059","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

Generation of spiral bending waves in a rotating galactic stellar disk of finite thickness 有限厚度旋转星系恒星盘中螺旋弯曲波的产生

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-08 DOI: 10.1007/s10509-026-04651-8

Evgeny Griv, Asher Yahalom

{"title":"Generation of spiral bending waves in a rotating galactic stellar disk of finite thickness","authors":"Evgeny Griv, Asher Yahalom","doi":"10.1007/s10509-026-04651-8","DOIUrl":"10.1007/s10509-026-04651-8","url":null,"abstract":"<div><p>A self-gravitating rotation-flattened galactic disk of finite thickness composed of identical stars is considered, taking into account the stellar random motions. A dispersion relation is derived to describe the dynamics of spontaneous bending gravity perturbations developing in the system by exploring a linear kinetic theory based on the Poisson and collisionless Boltzmann equations. These perturbations, or vertical corrugations, compress/disperse the medium in the direction normal to the midplane and propagate horizontally, making the disk rippled. The self-excitation of oscillatory-growing, spiral bending waves via the wave-star resonant interaction is proposed to be responsible for the vertically short (<span>({sim } 200text{--}300)</span> pc), still radially long (<span>({sim} 2text{--}3)</span> kpc) wavelength corrugation. It is a collective effect, meaning it arises from the interaction of many stars with the perturbation’s gravitational field. Self-gravity effects, acting both in the disk’s vertical dimension and in dimensions parallel to the plane, are critically important for the formation and evolution of weakly unstable waves. The free kinetic energy associated with the disk’s circular rotation is one possible source of the wave energy’s growth. Such ripple structures antisymmetric to the midplane are often observed in disk galaxies seen edge-on, even in isolation, including the Milky Way.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 10","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04651-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149133060","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

Surrogate-based rapid accessibility assessment of Kuiper Belt object transfers 基于代理的柯伊伯带天体转移快速可达性评价

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-08 DOI: 10.1007/s10509-026-04650-9

Linzhi Meng, Xingyu Zhou, Dong Qiao, Xiangyu Li

{"title":"Surrogate-based rapid accessibility assessment of Kuiper Belt object transfers","authors":"Linzhi Meng, Xingyu Zhou, Dong Qiao, Xiangyu Li","doi":"10.1007/s10509-026-04650-9","DOIUrl":"10.1007/s10509-026-04650-9","url":null,"abstract":"<div><p>Rapid accessibility assessment is needed for Kuiper Belt Objects (KBOs), because direct multiple-gravity-assist trajectory optimisation is too costly for screening large target populations. This study developed a surrogate-based method for rapid assessment of prescribed KBO transfers. High-fidelity multiple-gravity-assist trajectory optimisation with deep-space manoeuvres provided labels for a Gaussian process regression (GPR) model that predicted the deep-space-manoeuvre-only transfer objective and time of flight from target-state representations. Seven representations were compared, including orbital elements and Cartesian, cylindrical, and spherical states sampled at fixed epochs. A multi-epoch Cartesian representation gave the most balanced performance across prediction and ranking tasks. Logarithmic target scaling improved prediction accuracy in the low-cost region, whereas uncertainty-guided adaptive sampling improved screening precision and recall at the tested 10% and 20% screening fractions. On an independent test set, GPR achieved a global mean absolute transfer-objective error of 0.673 km/s and a mean absolute time-of-flight error of 537.5 days. The mean absolute error was 0.133 km/s for cases whose validated transfer objective was below 1 km/s, and 0.245 km/s for cases selected by the surrogate as having a predicted transfer objective below the same threshold. The larger global mean reflected the sparse high-cost tail of the objective distribution. Applied to 2223 representative catalogue targets, the surrogate identified ten targets with the lowest predicted transfer objectives for subsequent multiple-gravity-assist and deep-space-manoeuvre validation. These results provide a rapid screening approach for the prescribed Earth–Jupiter–KBO transfer scenario.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 10","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132612","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

On the generation of magnetic helicity by the Kelvin-Helmholtz instability in 2.5D incompressible MHD 论2.5D不可压缩MHD中Kelvin-Helmholtz不稳定性产生的磁螺旋度

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-05 DOI: 10.1007/s10509-026-04648-3

Mahboub Hosseinpour

{"title":"On the generation of magnetic helicity by the Kelvin-Helmholtz instability in 2.5D incompressible MHD","authors":"Mahboub Hosseinpour","doi":"10.1007/s10509-026-04648-3","DOIUrl":"10.1007/s10509-026-04648-3","url":null,"abstract":"<div><p>We present an exact analytical theory demonstrating that the linear, ideal, incompressible Kelvin-Helmholtz instability (KHI) in a 2.5-dimensional magnetized plasma intrinsically generates a gauge-invariant regional relative magnetic helicity flux. The mechanism arises from the non-self-adjoint, non-normal nature of the MHD KHI operator, which produces a complex phase asymmetry in the eigenfunctions across the shear layer. This phase asymmetry drives a non-zero time-averaged helicity flux through the boundaries of any subvolume enclosing the shear layer, redistributing magnetic helicity within the closed system. We derive a closed-form analytical expression for the helicity injection rate. We apply our theory to solar coronal jets, where the KHI is frequently observed at the interface between the jet and the ambient plasma. For typical jet parameters—<span>(B_{0}approx 10)</span> G, a shear-flow Alfvén Mach number <span>(M_{A}approx 1.36)</span>, a layer half-width <span>(aapprox 100text{ km})</span>, and a perturbation wavelength <span>(lambda approx 10^{4}text{ km})</span>—the linear KHI injects helicity at a rate of <span>(sim 10^{14})</span> Wb<sup>2</sup> s<sup>−1</sup> into the jet boundary region. Over an e-folding time of 8 seconds, the accumulated helicity is comparable to the observed twist in active-region jets, suggesting that the KHI alone can provide the magnetic helicity needed for the helical structure and stability of coronal jets.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 10","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149098269","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

Light scattering from graphite powders - an experimental investigation 石墨粉末的光散射实验研究

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-02 DOI: 10.1007/s10509-026-04646-5

Dwaipayan Deb

{"title":"Light scattering from graphite powders - an experimental investigation","authors":"Dwaipayan Deb","doi":"10.1007/s10509-026-04646-5","DOIUrl":"10.1007/s10509-026-04646-5","url":null,"abstract":"<div><p>The light scattering behavior of powdered surfaces is of fundamental importance in planetary science, remote sensing, aerosol physics, and optical material characterization. Airless planetary bodies such as asteroids and the Moon are covered with regolith, a layer of unconsolidated particulate material whose optical response carries information about surface composition and physical properties. In this work, laboratory-based light scattering measurements are reported for two well-characterized graphite powder samples of different particle size ranges. Graphite is a relevant analog material due to its presence in carbonaceous (B- and C-type) asteroids and its strong optical absorption. Angular-dependent bidirectional reflectance measurements were performed using a goniometric setup described in (Deb 2020) with monochromatic illumination at <span>(535~nm)</span>. The samples were independently characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and particle size analysis (PSA). The resulting scattering phase curves reveal a non-trivial dependence on particle size, a crossover behavior is observed in the reflectance curves, consistent with Kamei and Nakamura (2002) for their graphite samples. at intermediate phase angles. These experimental datasets provide reliable ground-truth inputs for theoretical modeling of light scattering from irregular, absorbing particulate surfaces and are relevant for the interpretation of remote sensing and in-situ spacecraft observations.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 10","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149098596","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

Cumulative gravitational time dilations across the universe 整个宇宙的累积引力时间膨胀

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-10-01 DOI: 10.1007/s10509-026-04645-6

Richard Petarius III, Robert J. Nemiroff

引用次数: 0

Long-term X-ray variability of the NLS1 Ark 564 NLS1 Ark 564的长期x射线变异

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-09-30 DOI: 10.1007/s10509-026-04643-8

P R Neha, Nikita S. Arun, Savithri H. Ezhikode, Ranjeev Misra, Bari Maqbool, Jeena K, Joe Jacob

{"title":"Long-term X-ray variability of the NLS1 Ark 564","authors":"P R Neha, Nikita S. Arun, Savithri H. Ezhikode, Ranjeev Misra, Bari Maqbool, Jeena K, Joe Jacob","doi":"10.1007/s10509-026-04643-8","DOIUrl":"10.1007/s10509-026-04643-8","url":null,"abstract":"<div><p>We present a systematic spectral study of the X-ray emission from the Narrow-Line Seyfert 1 (NLS1) galaxy Ark 564 using <i>Swift</i>/XRT observations spanning sixteen years. The source exhibits significant variability in both the soft and hard X-ray bands, along with a strong positive correlation between them, indicating a closely coupled emission mechanism within the accretion flow-corona system. A simple absorbed power-law model is statistically insufficient to describe the spectra, confirming the presence of an additional soft component. To investigate the origin of the soft excess, we performed multi-model spectral fitting. Incorporating a warm Comptonization component yields a statistically improved fit, supporting the scenario in which the soft excess arises from Comptonization in a warm, optically thick corona. We also applied a relativistic reflection model to representative observations; however, given the moderate spectral resolution and limited high-energy coverage of <i>Swift</i>/XRT, the current data do not allow us to robustly determine whether reflection provides a superior or physically preferred description. Our results indicate that warm Comptonization offers a consistent explanation for the observed soft excess in Ark 564 within the limitations of the available data, while deeper broadband observations are required to definitively distinguish between competing models and comprehensively characterise the long-term X-ray spectral variability of the source.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 9","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149133384","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

Closed-field electron acceleration in the solar corona: insights from J- and U-type solar radio bursts 日冕中的闭合场电子加速：来自J型和u型太阳射电暴的见解

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-09-29 DOI: 10.1007/s10509-026-04639-4

Shirsh Lata Soni, Vandna Luthra, Jaskirat Singh, Rakhi Suklan, Tushar Kumar N. Bhatt, Rajmal Jain

{"title":"Closed-field electron acceleration in the solar corona: insights from J- and U-type solar radio bursts","authors":"Shirsh Lata Soni, Vandna Luthra, Jaskirat Singh, Rakhi Suklan, Tushar Kumar N. Bhatt, Rajmal Jain","doi":"10.1007/s10509-026-04639-4","DOIUrl":"10.1007/s10509-026-04639-4","url":null,"abstract":"<div><p>Solar radio bursts (SRBs) provide key diagnostics of energetic electron propagation and coronal magnetic field structures. Among them, J- and U-type bursts are particularly valuable for tracing electron motion along closed magnetic loops, yet they remain less explored than type III bursts in open field lines. Using high-resolution dynamic spectra from the e-CALLISTO network, we analyzed a total of 38 SRB events (J-type 18 events and U-type 20 events) observed during the ascending phase of Solar Cycle 25, from June 2020 to December 2024, to characterize their spectral morphology, frequency drift, and magnetic connectivity. Complementary, Solar Dynamic Observatory/Helioseismic Magnetic Imager (SDO/HMI), Potential-Field Source-Surface Models (PFSS) extrapolations, and SDO/Atmospheric Imaging Assembly (AIA) extreme ultraviolet (EUV) imaging have been used to identify associated active regions and loop geometries. Approximately 30% of the events occurred without associated flares, indicating that small-scale reconnections can also produce SRBs. Application of the Newkirk density model yielded that the drift-rate analysis reveals broadly similar descending branches for J- and U-type SRBs but subtle asymmetries in ascending branches; steeper drift in J-type and smoother drift in U-type, indicating differences in electron propagation and density structuring between low-lying and extended closed coronal loops. For 19 of 38 events, constrained by the PFSS upper boundary (2.5 Rs), the loop heights inferred from the Newkirk model agree with PFSS within ±0.5 Rs, although PFSS tends to underestimate more extended structures. These results demonstrate the diagnostic potential of J- and U-type SRBs for probing electron propagation and closed magnetic structures in the solar corona.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 9","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04639-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149133197","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

Coronal mass ejections from young Suns: an observational view through the solar–stellar connection 年轻太阳的日冕物质抛射：通过日-星联系的观测视图

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-09-24 DOI: 10.1007/s10509-026-04641-w

Kosuke Namekata

{"title":"Coronal mass ejections from young Suns: an observational view through the solar–stellar connection","authors":"Kosuke Namekata","doi":"10.1007/s10509-026-04641-w","DOIUrl":"10.1007/s10509-026-04641-w","url":null,"abstract":"<div><p>Kepler and TESS have revealed that magnetically active stars frequently produce flares and superflares, raising the possibility that frequent, fast, and massive coronal mass ejections (CMEs) may affect planetary space weather environments. However, observational constraints on stellar CMEs remain extremely limited. Several diagnostics, including Doppler-shifted spectral lines, coronal dimming, and radio bursts, have been explored mainly for cool dwarfs, while recent observations have begun to extend these searches to young solar-type stars, which serve as important benchmarks for the solar–stellar connection. The goal of this review is to summarize the current understanding and recent observational progress on CME signatures from young solar-type stars, with a primary focus on Doppler-shift methods. It examines how these signatures resemble solar observations and models, what the inferred physical properties can tell us about the occurrence of stellar CMEs and their contribution to stellar mass loss, and how Doppler-shift signatures can be connected with multi-wavelength diagnostics. Comparisons with CME candidates from cool dwarfs and close binaries further place these signatures in the broader context of stellar CMEs in different stellar environments. These results have important implications for the space weather environments of young planets, while also pointing to key directions for future observations and modeling.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 9","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04641-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149034972","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