Pub Date : 2023-11-09DOI: 10.3389/fspas.2023.1201921
Yongli Wei, Dinghan Zhu, Zongxiang Li, Lihua Wang, Yuan Wang, Tianchi Zhang, Bin Xing, Baofeng Cao, Peng Li
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.
{"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}
Pub Date : 2023-11-09DOI: 10.3389/fspas.2023.1272771
Clare Dobbs
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.
{"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}
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.
准确地了解光核反应引起的异构体产率(IR)对于研究核结构和反应机理至关重要。由于Ho靶的自然丰度为100%，并且其残余核素具有良好的衰变特性，因此Ho是红外研究的一个很好的候选者。方法:实验研究了激光加速电子束诱导164m, g Ho的光子中子产生。离线检测了活化Ho箔的γ射线能谱。由于164m Ho的直接跃迁没有被成功地观测到，我们建议仅使用基态衰变的光峰计数来提取164m, g Ho的IRs。结果:提取164m, g Ho的产率分别为(0.45±0.10)× 10.6和(1.48±0.14)× 10.6 /次激光。所得IR为0.30±0.08，有效γ射线能量为12.65 MeV。讨论:然后将现有数据、可用实验数据和TALYS计算结果进行比较，以检验激发能的作用。研究发现，除了巨偶极子共振外，激发能效应对红外光谱的测定也起着关键作用。
{"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}
Pub Date : 2023-11-07DOI: 10.3389/fspas.2023.1306279
Jiawei Zhang, Qiaoling Li, Shuhan Li, Jing Liu
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.
先前的案例研究表明，太阳风条件的变化对赤道电离层电动力学有显著影响。然而，关于这一主题的统计研究有限，削弱了我们对太阳风、磁层和赤道电离层电动力学之间耦合的理解。方法:对2001 ~ 2021年南美赤道电喷流(EEJ)的长期数据进行年代叠加分析，研究赤道电离层电场对太阳风速度、密度、动压和行星际磁场(IMF) B z的阶跃变化的响应。结果:我们的研究表明，太阳风速度、密度和动压的阶梯变化可以在~ 20-40 min内触发EEJ的变化。EEJ对太阳风速度变化的敏感性最高，而对动压变化的敏感性相对较低。此外，EEJ对北向IMF B z的响应比南向IMF B z的响应更大。讨论:我们的工作提供了太阳风变化如何导致低纬度电离层EEJ变化的统计证据。我们推测太阳风条件的变化引起磁层变形和磁重联率的变化，从而导致电离层电场的波动和由此产生的EEJ变化。
{"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}
Pub Date : 2023-11-07DOI: 10.3389/fspas.2023.1174029
Faisal Javed, Abdul Basit, Aylin Caliskan, Ertan Güdekli
This study examines the thermodynamics of charged anti-de Sitter (AdS) black holes (BHs) with nonlinear electrodynamics (NED) using quasinormal modes (QNMs) and thermal fluctuations. For this purpose, we calculate the Hawking temperature and discuss the stable configuration of the considered black hole using heat capacity. First, we study the interesting aspects of the emission of energy. Then, we explore the effects of thermal corrections on thermodynamic quantities and their corrected energies. We study the phase transitions of the system in the background of thermal fluctuations. It is concluded that the presence of a coupling constant enhances the thermodynamically stable configuration of uncharged and charged AdS BH geometries. We highlight that our results are in good agreement with the thermodynamics of the previous black hole solutions and assumptions presented in the literature.
{"title":"Thermal fluctuations, QNMs, and emission energy of charged ADS black hole with nonlinear electrodynamics","authors":"Faisal Javed, Abdul Basit, Aylin Caliskan, Ertan Güdekli","doi":"10.3389/fspas.2023.1174029","DOIUrl":"https://doi.org/10.3389/fspas.2023.1174029","url":null,"abstract":"This study examines the thermodynamics of charged anti-de Sitter (AdS) black holes (BHs) with nonlinear electrodynamics (NED) using quasinormal modes (QNMs) and thermal fluctuations. For this purpose, we calculate the Hawking temperature and discuss the stable configuration of the considered black hole using heat capacity. First, we study the interesting aspects of the emission of energy. Then, we explore the effects of thermal corrections on thermodynamic quantities and their corrected energies. We study the phase transitions of the system in the background of thermal fluctuations. It is concluded that the presence of a coupling constant enhances the thermodynamically stable configuration of uncharged and charged AdS BH geometries. We highlight that our results are in good agreement with the thermodynamics of the previous black hole solutions and assumptions presented in the literature.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"152 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135476120","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}
Pub Date : 2023-11-07DOI: 10.3389/fspas.2023.1274760
J. Joseph, A. N. Jaynes, W. S. Kurth, J. D. Menietti, J. E. P. Connerney, S. J. Bolton
Electron cyclotron harmonic (ECH) waves along with whistler mode waves are suggested to be responsible for causing the persistent diffuse aurora in Jupiter. In this work, for the first time we systematically analyze the ECH waves in the Jovian inner magnetosphere, which was surveyed by Juno during the later orbits (>25). We find that in the Jovian inner magnetosphere, ECH waves occur in two specific regions—one equatorial and the other off-equatorial, just outside the Io torus. Equatorial ECH waves have higher intensity compared to their off-equatorial counterpart. We also notice an overlap between the region of mid-latitude hot injections and the region of off-equatorial ECH wave occurrence. Finally, we show an event to describe the complex nature of ECH wave growth/damping varying with particle density structures of the injection region at mid-latitude.
{"title":"Electron cyclotron harmonic waves in Jovian magnetosphere as seen by Juno","authors":"J. Joseph, A. N. Jaynes, W. S. Kurth, J. D. Menietti, J. E. P. Connerney, S. J. Bolton","doi":"10.3389/fspas.2023.1274760","DOIUrl":"https://doi.org/10.3389/fspas.2023.1274760","url":null,"abstract":"Electron cyclotron harmonic (ECH) waves along with whistler mode waves are suggested to be responsible for causing the persistent diffuse aurora in Jupiter. In this work, for the first time we systematically analyze the ECH waves in the Jovian inner magnetosphere, which was surveyed by Juno during the later orbits (>25). We find that in the Jovian inner magnetosphere, ECH waves occur in two specific regions—one equatorial and the other off-equatorial, just outside the Io torus. Equatorial ECH waves have higher intensity compared to their off-equatorial counterpart. We also notice an overlap between the region of mid-latitude hot injections and the region of off-equatorial ECH wave occurrence. Finally, we show an event to describe the complex nature of ECH wave growth/damping varying with particle density structures of the injection region at mid-latitude.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"50 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135476495","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}
Pub Date : 2023-11-07DOI: 10.3389/fspas.2023.1320143
Dmytro Kotov, Oleksandr Bogomaz
• 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].
{"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}
Slow solar wind, sharing magnetic and plasma properties typical of fast wind, the so-called slow Alfvénic wind, has been widely observed in the heliosphere. Here, we report an analysis of the turbulent properties of a slow Alfvénic stream observed by Solar Orbiter at 0.64 AU. This solar wind stream is characterized by well distinguishable regions, namely, a main portion, an intermediate region, and a rarefaction region. Each of those intervals have been studied separately, in order to enhance similarities and differences in their turbulence properties. Coherent structures naturally emerge over different time/spatial scales and their characteristics at ion scales have been investigated. The presence of these intermittent events have been found to be closely related to kinetic features in the ion (both proton and alpha particles) velocity distribution functions, suggesting a fundamental role in the kinetic physical processes that mediate the sub-ion turbulence cascade.
{"title":"Ion kinetic effects linked to magnetic field discontinuities in the slow Alfvénic wind observed by Solar Orbiter in the inner heliosphere","authors":"Denise Perrone, Adriana Settino, Rossana De Marco, Raffaella D’Amicis, Silvia Perri","doi":"10.3389/fspas.2023.1250219","DOIUrl":"https://doi.org/10.3389/fspas.2023.1250219","url":null,"abstract":"Slow solar wind, sharing magnetic and plasma properties typical of fast wind, the so-called slow Alfvénic wind, has been widely observed in the heliosphere. Here, we report an analysis of the turbulent properties of a slow Alfvénic stream observed by Solar Orbiter at 0.64 AU. This solar wind stream is characterized by well distinguishable regions, namely, a main portion, an intermediate region, and a rarefaction region. Each of those intervals have been studied separately, in order to enhance similarities and differences in their turbulence properties. Coherent structures naturally emerge over different time/spatial scales and their characteristics at ion scales have been investigated. The presence of these intermittent events have been found to be closely related to kinetic features in the ion (both proton and alpha particles) velocity distribution functions, suggesting a fundamental role in the kinetic physical processes that mediate the sub-ion turbulence cascade.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"1984 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135635586","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}
Pub Date : 2023-11-02DOI: 10.3389/fspas.2023.1275516
Liu Danyang, Cheng Weiming
The study of Martian surface topography is important for understanding the geological evolution of Mars and revealing the spatial differentiation of the Martian landscape. Identifying typical landform units is a fundamental task when studying the origin and evolution of Mars and provides important information for landing on and exploring Mars, as well as estimating the age of the Martian surface and inferring the evolution of the Earth’s environment. In this paper, we first investigate Mars exploration, data acquisition and mapping, and the classification methods of Martian landforms. Then, the identification of several typical Martian landform types, such as aeolian landforms, fluvial landforms, and impact landforms, is shown in detail. Finally, the prospects of Mars data acquisition, landform mapping, and the construction and identification of the Martian landform classification system are presented. The construction of the Martian landform classification system and the identification of typical Martian landforms using deep learning are important development directions in planetary science.
{"title":"Progress and prospects for research on Martian topographic features and typical landform identification","authors":"Liu Danyang, Cheng Weiming","doi":"10.3389/fspas.2023.1275516","DOIUrl":"https://doi.org/10.3389/fspas.2023.1275516","url":null,"abstract":"The study of Martian surface topography is important for understanding the geological evolution of Mars and revealing the spatial differentiation of the Martian landscape. Identifying typical landform units is a fundamental task when studying the origin and evolution of Mars and provides important information for landing on and exploring Mars, as well as estimating the age of the Martian surface and inferring the evolution of the Earth’s environment. In this paper, we first investigate Mars exploration, data acquisition and mapping, and the classification methods of Martian landforms. Then, the identification of several typical Martian landform types, such as aeolian landforms, fluvial landforms, and impact landforms, is shown in detail. Finally, the prospects of Mars data acquisition, landform mapping, and the construction and identification of the Martian landform classification system are presented. The construction of the Martian landform classification system and the identification of typical Martian landforms using deep learning are important development directions in planetary science.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"32 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135934239","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}
Pub Date : 2023-11-02DOI: 10.3389/fspas.2023.1264226
Russell A. Howard, Angelos Vourlidas, Guillermo Stenborg
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.
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