Frontiers in Astronomy and Space Sciences最新文献_第3页

Dispersive propagation of nuclear electromagnetic pulse in the ionosphere 核电磁脉冲在电离层中的色散传播

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-09 DOI: 10.3389/fspas.2023.1201921

Yongli Wei, Dinghan Zhu, Zongxiang Li, Lihua Wang, Yuan Wang, Tianchi Zhang, Bin Xing, Baofeng Cao, Peng Li

{"title":"Dispersive propagation of nuclear electromagnetic pulse in the ionosphere","authors":"Yongli Wei, Dinghan Zhu, Zongxiang Li, Lihua Wang, Yuan Wang, Tianchi Zhang, Bin Xing, Baofeng Cao, Peng Li","doi":"10.3389/fspas.2023.1201921","DOIUrl":"https://doi.org/10.3389/fspas.2023.1201921","url":null,"abstract":"Introduction: On the propagation path to the satellite, the ionosphere will distort the nuclear electromagnetic pulse (NEMP) and change its physical properties. Methods: This paper proposes a method for calculating the propagation of NEMP to the satellite. The method decomposes NEMP into the superposition of simple harmonic waves, and each simple harmonic wave is calculated separately in the ionosphere. With the consideration of different time of arrival and critical frequency of the ionosphere, the NEMP after propagating in the ionosphere is obtained by superposition of simple harmonic waves in time domain rather than the inverse Fourier transform which will erase the time domain information. Results: The results show that NEMP is dispersive in ionosphere with the pulse broadened, the speeds changed and the bandwidth narrowed. The time-frequency spectrum can provide the frequency band where the signal energy is located. Discussion: Our proposed method provides a simple and effective way to calculate the NEMP propagation in the ionosphere, which should afford help to the design of NEMP receivers and the selection of satellite orbit altitude.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":" 36","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135291808","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}

引用次数: 0

2a Results: galaxy to cloud scales 2a结果:星系到云的尺度

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-09 DOI: 10.3389/fspas.2023.1272771

Clare Dobbs

{"title":"2a Results: galaxy to cloud scales","authors":"Clare Dobbs","doi":"10.3389/fspas.2023.1272771","DOIUrl":"https://doi.org/10.3389/fspas.2023.1272771","url":null,"abstract":"Simulations from the scales of isolated galaxies to clouds have been instrumental in informing us about molecular cloud formation and evolution. Simulations are able to investigate the roles of gravity, feedback, turbulence, heating and cooling, and magnetic fields on the physics of the interstellar medium, and star formation. Compared to simulations of individual clouds, galactic and sub-galactic scale simulations can include larger galactic scale processes such as spiral arms, bars, and larger supernovae bubbles, which may influence star formation. Simulations show cloud properties and lifetimes in broad agreement with observations. Gravity and spiral arms are required to produce more massive GMCs, whilst stellar feedback, likely photoionisation, leads to relatively short cloud lifetimes. On larger scales, supernovae may be more dominant in driving the structure and dynamics, but photoionisation may still have a role. In terms of the dynamics, feedback is probably the main driver of velocity dispersions, but large scale processes such as gravity and spiral arms may also be significant. Magnetic fields are generally found to decrease star formation on galaxy or cloud scales, and simulations are ongoing to study whether clouds are sub or supercritical on different scales in galaxy scale simulations. Simulations on subgalactic scales, or zoom in simulations, allow better resolution of feedback processes, filamentary structure within clouds, and the study of stellar clusters.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":" 38","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135292445","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}

引用次数: 0

Study of the isomeric yield ratio in the photoneutron reaction of natural holmium induced by laser-accelerated electron beams 激光加速电子束诱导天然钬光-中子反应中异构体产率的研究

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-08 DOI: 10.3389/fspas.2023.1265919

Jingli Zhang, Wei Qi, Wenru Fan, Zongwei Cao, Kaijun Luo, Changxiang Tan, Xiaohui Zhang, Zhigang Deng, Zhimeng Zhang, Xinxiang Li, Yun Yuan, Wen Luo, Weimin Zhou

{"title":"Study of the isomeric yield ratio in the photoneutron reaction of natural holmium induced by laser-accelerated electron beams","authors":"Jingli Zhang, Wei Qi, Wenru Fan, Zongwei Cao, Kaijun Luo, Changxiang Tan, Xiaohui Zhang, Zhigang Deng, Zhimeng Zhang, Xinxiang Li, Yun Yuan, Wen Luo, Weimin Zhou","doi":"10.3389/fspas.2023.1265919","DOIUrl":"https://doi.org/10.3389/fspas.2023.1265919","url":null,"abstract":"Introduction: An accurate knowledge of the isomeric yield ratio (IR) induced by the photonuclear reaction is crucial to study the nuclear structure and reaction mechanisms. 165 Ho is a good candidate for the investigation of the IR since the Ho target has a natural abundance of 100% and the residual nuclide has a good decay property. Methods: In this study, the photoneutron production of 164m, g Ho induced by laser-accelerated electron beams is investigated experimentally. The γ-ray spectra of activated Ho foils are off-line detected. Since the direct transitions from the 164m Ho are not successfully observed, we propose to extract the IRs of the 164m, g Ho using only the photopeak counts from the ground-state decay. Results: The production yields of 164m, g Ho are extracted to be (0.45 ± 0.10) × 10 6 and (1.48 ± 0.14) × 10 6 per laser shot, respectively. The resulting IR is obtained to be 0.30 ± 0.08 at the effective γ-ray energy of 12.65 MeV. Discussion: The present data, available experimental data, and TALYS calculations are then compared to examine the role of the excitation energy. It is found that besides the giant dipole resonance, the excitation energy effect also plays a key role in the determination of the IRs.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"359 20","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135393246","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}

引用次数: 0

Statistical analysis of equatorial electrojet responses to the transient changes of solar wind conditions 赤道电喷流对太阳风瞬态变化响应的统计分析

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-07 DOI: 10.3389/fspas.2023.1306279

Jiawei Zhang, Qiaoling Li, Shuhan Li, Jing Liu

{"title":"Statistical analysis of equatorial electrojet responses to the transient changes of solar wind conditions","authors":"Jiawei Zhang, Qiaoling Li, Shuhan Li, Jing Liu","doi":"10.3389/fspas.2023.1306279","DOIUrl":"https://doi.org/10.3389/fspas.2023.1306279","url":null,"abstract":"Introduction: Prior case studies have indicated that changes in solar wind conditions have a significant impact on equatorial ionospheric electrodynamics. However, there have been limited statistical studies on this topic, impairing our understanding of the coupling between solar wind, magnetosphere, and equatorial ionosphere electrodynamics. Methods: In this study, we conducted a superposed epoch analysis of long-term data from the South America equatorial electrojet (EEJ) spanning from 2001 to 2021 examining the responses of the equatorial ionospheric electric field to step-like changes in solar wind velocity, density, dynamic pressure, and interplanetary magnetic field (IMF) B z . Result: Our study shows that step-like changes in solar wind velocity, density, and dynamic pressure can trigger changes in EEJ within ∼20–40 min. EEJ exhibits the highest sensitivity to variations in solar wind velocity while being relatively less sensitive to changes in dynamic pressure. Furthermore, the response of EEJ shows greater responsiveness to northward IMF B z compared to southward IMF B z . Discussion: Our work provides statistical evidence of how changes in solar wind can lead to changes in low-latitude ionospheric EEJ. We inferred that the changes in solar wind conditions cause magnetospheric deformation and changes in magnetic reconnection rates, leading to the fluctuations of the ionospheric electric field and the resultant EEJ variations.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"69 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135476705","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}

引用次数: 0

Thermal fluctuations, QNMs, and emission energy of charged ADS black hole with nonlinear electrodynamics 非线性电动力学下带电ADS黑洞的热涨落、QNMs和发射能量

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-07 DOI: 10.3389/fspas.2023.1174029

Faisal Javed, Abdul Basit, Aylin Caliskan, Ertan Güdekli

引用次数: 0

Electron cyclotron harmonic waves in Jovian magnetosphere as seen by Juno 朱诺号观测到的木星磁层中的电子回旋谐波

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-07 DOI: 10.3389/fspas.2023.1274760

J. Joseph, A. N. Jaynes, W. S. Kurth, J. D. Menietti, J. E. P. Connerney, S. J. Bolton

引用次数: 0

Corrigendum: Hydrogen atoms near the exobase are cold: independent observations do not support the hot exosphere concept 勘误:靠近外逸层的氢原子是冷的:独立观测不支持热的外逸层概念

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-07 DOI: 10.3389/fspas.2023.1320143

Dmytro Kotov, Oleksandr Bogomaz

{"title":"Corrigendum: Hydrogen atoms near the exobase are cold: independent observations do not support the hot exosphere concept","authors":"Dmytro Kotov, Oleksandr Bogomaz","doi":"10.3389/fspas.2023.1320143","DOIUrl":"https://doi.org/10.3389/fspas.2023.1320143","url":null,"abstract":"• please read through all the templates before choosing • pick the most relevant text template(s) from the following page and delete all others.• edit the text as necessary, ensuring that the original incorrect text is included for the record, please see the below. • please do not use any extra formatting when editing the templates, and only modify the red text unless absolutely necessary • submit to Frontiers following the instructions on this page.When the original text contained incorrect information, to preserve the scientific record, please include that text when editing the below templates. For example:There was a mistake in the Funding statement, an incorrect number was used. The correct number is \"2015C03Bd051.\". The publisher apologizes for this mistake.The original version of this article has been updated. In the published article, there was an error. [In the published article, there was a typo in the Text. The word \"hot\" was used incorrectly instead of a proper word \"cold\" as shown below. Despite the rest of phrase after the word indicate for the readers that the \"hot\" is incorrect, this typo may certainly confuse the readers].","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"217 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135476248","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}

引用次数: 0

Ion kinetic effects linked to magnetic field discontinuities in the slow Alfvénic wind observed by Solar Orbiter in the inner heliosphere 由太阳轨道器在内日球层观测到的与慢alfv<s:1>风中磁场不连续有关的离子动力学效应

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-06 DOI: 10.3389/fspas.2023.1250219

Denise Perrone, Adriana Settino, Rossana De Marco, Raffaella D’Amicis, Silvia Perri

引用次数: 0

Progress and prospects for research on Martian topographic features and typical landform identification 火星地形特征与典型地貌识别研究进展与展望

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-02 DOI: 10.3389/fspas.2023.1275516

Liu Danyang, Cheng Weiming

引用次数: 0

The evolution of our understanding of coronal mass ejections 我们对日冕物质抛射理解的演变

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-11-02 DOI: 10.3389/fspas.2023.1264226

Russell A. Howard, Angelos Vourlidas, Guillermo Stenborg

{"title":"The evolution of our understanding of coronal mass ejections","authors":"Russell A. Howard, Angelos Vourlidas, Guillermo Stenborg","doi":"10.3389/fspas.2023.1264226","DOIUrl":"https://doi.org/10.3389/fspas.2023.1264226","url":null,"abstract":"The unexpected observation of a sudden expulsion of mass through the solar corona in 1971 opened up a new field of interest in solar and stellar physics. The discovery came from a white-light coronagraph, which creates an artificial eclipse of the Sun, enabling the viewing of the faint glow from the corona. This observation was followed by many more observations and new missions. In the five decades since that discovery, there have been five generations of coronagraphs, each with improved performance, enabling continued understanding of the phenomena, which became known as Coronal Mass Ejection (CME) events. The conceptualization of the CME structure evolved from the elementary 2-dimensional loop to basically two fundamental types: a 3-dimensional magnetic flux rope and a non-magnetic eruption from pseudo-streamers. The former persists to 1 AU and beyond, whereas the latter dissipates by 15 R ⊙ . Historically, most of the studies have been devoted to understanding the CME large-scale structure and its associations, but this is changing. With the advent of the fourth and fifth coronagraph generations, more attention is being devoted to the their internal structure and initiation mechanisms. In this review, we describe the evolution of CME observations and their associations with other solar and heliospheric phenomena, with one of the more important correlations being its recognition as a driver of space-weather. We conclude with a brief overview of open questions and present some ideas for future observations.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"16 46","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135973768","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}

引用次数: 0