Pub Date : 2024-07-15DOI: 10.3389/fspas.2024.1402031
Lin-Qiao Jiang, Jie Zheng
GZ And is a variable star within the visually observed multiple-star system ADS 1693. Recent observations have yielded new light curves for GZ And, obtained using the Xinglong 85-cm telescope and the Transiting Exoplanet Survey Satellite (TESS) satellite. These light curves, along with radial velocity curves, were analyzed simultaneously to ascertain the fundamental physical parameters of GZ And’s components. The findings indicate that the primary star has a mass of M1 = 0.57 (4)M⊙, radius of R1 = 0.75 (2)R⊙, and luminosity of L1 = 0.42 (2)L⊙. The secondary star is characterized by a mass of M2 = 1.19 (9)M⊙, radius of R2 = 1.04 (3)R⊙, and luminosity of L2 = 0.63 (3)L⊙. Their orbital separation is determined to be a = 2.30 (6)R⊙. An analysis of the accumulated times of light minima reveals that GZ And is undergoing orbital period variations at a rate of dP/dt = −7.58 (7) × 10−8day ⋅ year−1, likely due to mass transfer from the more massive component to its lighter counterpart at a rate of dM2/dt = −9.06 (8) × 10−8M⊙⋅ year−1. Additionally, distance measurements for the component stars in ADS 1693, derived from Gaia DR3 astrometric data, suggest that ADS 1693A (GZ And) and ADS 1693B are gravitationally bound and likely originated from the same molecular cloud, sharing similar ages. This evidence supports the classification of GZ And as a W UMa-type contact binary within a physically associated triple system.
{"title":"Investigation of a W UMa-type contact binary GZ And in a physical triple system","authors":"Lin-Qiao Jiang, Jie Zheng","doi":"10.3389/fspas.2024.1402031","DOIUrl":"https://doi.org/10.3389/fspas.2024.1402031","url":null,"abstract":"GZ And is a variable star within the visually observed multiple-star system ADS 1693. Recent observations have yielded new light curves for GZ And, obtained using the Xinglong 85-cm telescope and the Transiting Exoplanet Survey Satellite (TESS) satellite. These light curves, along with radial velocity curves, were analyzed simultaneously to ascertain the fundamental physical parameters of GZ And’s components. The findings indicate that the primary star has a mass of M1 = 0.57 (4)M⊙, radius of R1 = 0.75 (2)R⊙, and luminosity of L1 = 0.42 (2)L⊙. The secondary star is characterized by a mass of M2 = 1.19 (9)M⊙, radius of R2 = 1.04 (3)R⊙, and luminosity of L2 = 0.63 (3)L⊙. Their orbital separation is determined to be a = 2.30 (6)R⊙. An analysis of the accumulated times of light minima reveals that GZ And is undergoing orbital period variations at a rate of dP/dt = −7.58 (7) × 10−8day ⋅ year−1, likely due to mass transfer from the more massive component to its lighter counterpart at a rate of dM2/dt = −9.06 (8) × 10−8M⊙⋅ year−1. Additionally, distance measurements for the component stars in ADS 1693, derived from Gaia DR3 astrometric data, suggest that ADS 1693A (GZ And) and ADS 1693B are gravitationally bound and likely originated from the same molecular cloud, sharing similar ages. This evidence supports the classification of GZ And as a W UMa-type contact binary within a physically associated triple system.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"42 49","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141644985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-11DOI: 10.3389/fspas.2024.1383746
Xiaoyan Xie, Gang Li, Katharine K. Reeves, Tingyu Gou
Multiple pieces of evidence have revealed the important role of turbulence in physical processes in solar eruptions, from particle acceleration to the suppression of conductive cooling. Radio observations of density variation have established a Kolmogorov-like spectrum for solar wind density disturbance. Close to the Sun, measurements from extreme ultraviolet (EUV) bands have been used to examine turbulence in the solar atmosphere. The Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory (SDO/AIA) has been frequently used for diagnosing plasma properties due to its complex coverage of temperature response. We compute structure functions (SFs) using SDO/AIA emission measurements for two example of plasma sheets. With the relationship of v ∼ b ∼ δn and δI∼δ(n0+δn)2∼δn (v, b, δn, and δI are turbulent velocity, magnetic field, number density, and intensity, respectively, and n0 is the background density), SFs of δI can be regarded as a proxy for those of the turbulent v and b fields in the plasma sheet. We show that by properly accounting for the radial dependence of the emission line intensity, an SF method is capable of probing the presence of turbulence from SDO/AIA emission lines. Compared to in situ observations, performing SFs on EUV emissions is advantageous in studying turbulence behavior in the wave-vector space, and it opens a new window for investigating turbulence from massive SDO/AIA observations.
从粒子加速到抑制传导冷却，多种证据揭示了湍流在太阳爆发物理过程中的重要作用。对密度变化的无线电观测为太阳风密度扰动建立了一个类似于柯尔莫哥洛夫的频谱。在靠近太阳的地方，利用极紫外线（EUV）波段的测量来研究太阳大气中的湍流。太阳动力学天文台（SDO/AIA）上的大气成像组件因其复杂的温度响应覆盖范围而经常被用于诊断等离子体特性。我们利用 SDO/AIA 对两个等离子体片的发射测量来计算结构函数（SF）。根据 v ∼ b ∼ δn 和 δI ∼δ(n0+δn)2 ∼δn 的关系（v、b、δn 和 δI 分别为湍流速度、磁场、数量密度和强度，n0 为背景密度），δI 的结构函数可被视为等离子体片中湍流 v 场和 b 场的结构函数。我们的研究表明，通过适当考虑发射线强度的径向依赖性，SF 方法能够从 SDO/AIA 发射线中探测湍流的存在。与原位观测相比，对极紫外发射线进行 SF 在研究波矢量空间的湍流行为方面具有优势，它为从大质量 SDO/AIA 观测中研究湍流打开了一扇新窗口。
{"title":"Probing turbulence in solar flares from SDO/AIA emission lines","authors":"Xiaoyan Xie, Gang Li, Katharine K. Reeves, Tingyu Gou","doi":"10.3389/fspas.2024.1383746","DOIUrl":"https://doi.org/10.3389/fspas.2024.1383746","url":null,"abstract":"Multiple pieces of evidence have revealed the important role of turbulence in physical processes in solar eruptions, from particle acceleration to the suppression of conductive cooling. Radio observations of density variation have established a Kolmogorov-like spectrum for solar wind density disturbance. Close to the Sun, measurements from extreme ultraviolet (EUV) bands have been used to examine turbulence in the solar atmosphere. The Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory (SDO/AIA) has been frequently used for diagnosing plasma properties due to its complex coverage of temperature response. We compute structure functions (SFs) using SDO/AIA emission measurements for two example of plasma sheets. With the relationship of v ∼ b ∼ δn and δI∼δ(n0+δn)2∼δn (v, b, δn, and δI are turbulent velocity, magnetic field, number density, and intensity, respectively, and n0 is the background density), SFs of δI can be regarded as a proxy for those of the turbulent v and b fields in the plasma sheet. We show that by properly accounting for the radial dependence of the emission line intensity, an SF method is capable of probing the presence of turbulence from SDO/AIA emission lines. Compared to in situ observations, performing SFs on EUV emissions is advantageous in studying turbulence behavior in the wave-vector space, and it opens a new window for investigating turbulence from massive SDO/AIA observations.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"54 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141658280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.3389/fspas.2024.1392970
Peng Wu, Jian Li, Mao-Zheng Chen
Xinjiang Qitai is constructing a 110-m fully steerable radio telescope (QiTai radio Telescope [QTT]) equipped with a phased array feeds (PAF) receiver, which will install the focal plane operating from 0.7 to 1.8 GHz. In this article, we introduce a PAF receiver model for beamforming, and the numerical model of the internal and external noise for this PAF receiver is provided using electromagnetic field simulation software. The linear constraint minimum variance (LCMV) algorithm is used to simulate the interference mitigation. The interference mitigation rate is from 0.581 to 0.921, and the signal restoration rate is from 0.998 to 1.512 within the error range of an interference arrival angle of 10°. This conclusion can be used in the signal correction of the PAF receiver for interference mitigation.
{"title":"Numerical model of the QiTai radio Telescope PAF receiver signal and simulation of interference mitigation","authors":"Peng Wu, Jian Li, Mao-Zheng Chen","doi":"10.3389/fspas.2024.1392970","DOIUrl":"https://doi.org/10.3389/fspas.2024.1392970","url":null,"abstract":"Xinjiang Qitai is constructing a 110-m fully steerable radio telescope (QiTai radio Telescope [QTT]) equipped with a phased array feeds (PAF) receiver, which will install the focal plane operating from 0.7 to 1.8 GHz. In this article, we introduce a PAF receiver model for beamforming, and the numerical model of the internal and external noise for this PAF receiver is provided using electromagnetic field simulation software. The linear constraint minimum variance (LCMV) algorithm is used to simulate the interference mitigation. The interference mitigation rate is from 0.581 to 0.921, and the signal restoration rate is from 0.998 to 1.512 within the error range of an interference arrival angle of 10°. This conclusion can be used in the signal correction of the PAF receiver for interference mitigation.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"3 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.3389/fspas.2024.1426267
Ying Zou, Cheng Sheng, Mark Conde, Xueling Shi, William A. Bristow, Yen-Jung Joanne Wu
Winds in the nighttime upper thermosphere are often observed to mimic the ionospheric plasma convection at polar latitudes, and whether the same is true for the daytime winds remains unclear. The dayside sector is subject to large temperature gradient set up by solar irradiance and it also contains the cusp, which is a hotspot of Poynting flux and a region with the strongest soft particle precipitation. We examine daytime winds using a Scanning Doppler Imager (SDI) located at the South Pole, and investigate their distribution under steadily positive and negative IMF By conditions. The results show that daytime winds exhibit significant differences from the plasma convection. Under negative IMF By conditions, winds flow in the same direction as the plasma zonally, but have a meridional component that is strongest in the auroral zone. As a result, winds are more poleward-directed than the plasma convection within the auroral zone, and more westward-directed in the polar cap. Under positive IMF By conditions, winds can flow zonally against the plasma in certain regions. For instance, they flow westward in the polar cap despite the eastward plasma convection there, forming a large angle relative to the plasma convection. The results indicate that ion drag may not be the most dominant force for daytime winds. Although the importance of various forcing terms cannot be resolved with the utilized dataset, we speculate that the pressure gradient force in the presence of cusp heating serves as one important contributor.
夜间热层上部的风经常被观测到模仿极地纬度的电离层等离子体对流，白天的风是否也是如此仍不清楚。日侧扇区受到太阳辐照度形成的巨大温度梯度的影响，它还包含尖顶，尖顶是波因廷通量的热点，也是软粒子降水最强的区域。我们利用位于南极的扫描多普勒成像仪（SDI）对昼间风进行了研究，并调查了它们在稳定的正负IMF By条件下的分布情况。结果表明，昼间风与等离子体对流存在显著差异。在负的 IMF By 条件下，风的流动方向与等离子带相同，但在极光带有最强的经向分量。因此，极光区内的风比等离子体对流更偏向极地，而在极冠区则更偏向西方。在正 IMF 条件下，某些区域的风会逆等离子体的方向流动。例如，在极冠，尽管等离子体对流向东，风却向西流动，与等离子体对流形成一个大角度。结果表明，离子阻力可能不是白天风的最主要作用力。虽然利用数据集无法确定各种作用力的重要性，但我们推测尖顶加热时的压力梯度力是一个重要的作用力。
{"title":"Dependence of daytime thermospheric winds on IMF By as measured from south pole","authors":"Ying Zou, Cheng Sheng, Mark Conde, Xueling Shi, William A. Bristow, Yen-Jung Joanne Wu","doi":"10.3389/fspas.2024.1426267","DOIUrl":"https://doi.org/10.3389/fspas.2024.1426267","url":null,"abstract":"Winds in the nighttime upper thermosphere are often observed to mimic the ionospheric plasma convection at polar latitudes, and whether the same is true for the daytime winds remains unclear. The dayside sector is subject to large temperature gradient set up by solar irradiance and it also contains the cusp, which is a hotspot of Poynting flux and a region with the strongest soft particle precipitation. We examine daytime winds using a Scanning Doppler Imager (SDI) located at the South Pole, and investigate their distribution under steadily positive and negative IMF By conditions. The results show that daytime winds exhibit significant differences from the plasma convection. Under negative IMF By conditions, winds flow in the same direction as the plasma zonally, but have a meridional component that is strongest in the auroral zone. As a result, winds are more poleward-directed than the plasma convection within the auroral zone, and more westward-directed in the polar cap. Under positive IMF By conditions, winds can flow zonally against the plasma in certain regions. For instance, they flow westward in the polar cap despite the eastward plasma convection there, forming a large angle relative to the plasma convection. The results indicate that ion drag may not be the most dominant force for daytime winds. Although the importance of various forcing terms cannot be resolved with the utilized dataset, we speculate that the pressure gradient force in the presence of cusp heating serves as one important contributor.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"4 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The presence of nucleus-shaped anomalous regions in the power spectrum image of the electric field VLF frequency band has been discovered in previous studies. To detect and analyze these nucleus-shaped abnormal areas and improve the recognition rate of nucleus-shaped abnormal areas, this paper proposes a new nucleus-shaped abnormal area detection model ODM_Unet (Omni-dimensional Dynamic Mobile U-net) based on U-net network. Firstly, the power spectrum image data used for training is created and labeled to form a dataset of nucleus-shaped anomalous regions; Secondly, the ODConv (Omni-dimensional Dynamic Convolution) module with embedded attention mechanism was introduced to improve the encoder, extracting nucleus-shaped anomaly region information from four dimensions and focusing on the features of different input data; An SDI (Semantics and Detail Infusion) module is introduced between the encoder and decoder to solve the problem of detail semantic loss in high-level images caused by the reduction of downsampling image size; In the decoder stage, the SCSE (Spatial and Channel Squeeze-and-Excitation) attention module is introduced to more finely adjust the feature maps output through the SDI module. The experimental results show that compared with the current popular semantic segmentation algorithms, the ODM_Unet model has the best detection performance in nucleus-shaped anomaly areas. Using this model to detect data from November 2021 to October 2022, it was found that the frequency of nucleus-shaped anomaly areas is mostly between 0 and 12.5KHz, with geographic spatial distribution ranging from 40° to 70° south and north latitudes, and magnetic latitude spatial distribution ranging from 58° to 80° south and north latitudes. This method has reference significance for detecting other types of spatial electromagnetic field disturbances.
{"title":"Research on identification of nucleus-shaped anomaly regions in space electric field","authors":"Xingsu Li, Zhong Li, Jianping Huang, Ying Han, Yumeng Huo, Junjie Song, Bo Hao","doi":"10.3389/fspas.2024.1431273","DOIUrl":"https://doi.org/10.3389/fspas.2024.1431273","url":null,"abstract":"The presence of nucleus-shaped anomalous regions in the power spectrum image of the electric field VLF frequency band has been discovered in previous studies. To detect and analyze these nucleus-shaped abnormal areas and improve the recognition rate of nucleus-shaped abnormal areas, this paper proposes a new nucleus-shaped abnormal area detection model ODM_Unet (Omni-dimensional Dynamic Mobile U-net) based on U-net network. Firstly, the power spectrum image data used for training is created and labeled to form a dataset of nucleus-shaped anomalous regions; Secondly, the ODConv (Omni-dimensional Dynamic Convolution) module with embedded attention mechanism was introduced to improve the encoder, extracting nucleus-shaped anomaly region information from four dimensions and focusing on the features of different input data; An SDI (Semantics and Detail Infusion) module is introduced between the encoder and decoder to solve the problem of detail semantic loss in high-level images caused by the reduction of downsampling image size; In the decoder stage, the SCSE (Spatial and Channel Squeeze-and-Excitation) attention module is introduced to more finely adjust the feature maps output through the SDI module. The experimental results show that compared with the current popular semantic segmentation algorithms, the ODM_Unet model has the best detection performance in nucleus-shaped anomaly areas. Using this model to detect data from November 2021 to October 2022, it was found that the frequency of nucleus-shaped anomaly areas is mostly between 0 and 12.5KHz, with geographic spatial distribution ranging from 40° to 70° south and north latitudes, and magnetic latitude spatial distribution ranging from 58° to 80° south and north latitudes. This method has reference significance for detecting other types of spatial electromagnetic field disturbances.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"81 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3389/fspas.2024.1394741
M. L. Allen, P. L. Biermann, L. Caramete, A. Chieffi, R. Chini, D. Frekers, L. Gergely, B. Harms, I. Jaroschewski, P. S. Joshi, P. P. Kronberg, E. Kun, A. Meli, E.-S. Seo, T. Stanev
Supermassive black hole (BH) mergers with spin-flips accelerate energetic particles through their relativistic precessing jets, producing high-energy neutrinos and finally gravitational waves (GWs). In star formation, massive stars form in pairs, triplets, and quadruplets, allowing second-generation mergers of the remnants with discrepant spin directions. The GW data support such a scenario. Earlier, we suggested that stellar mass BH mergers (visible in M82) with an associated spin-flip analogously allow the acceleration of energetic particles, with ensuing high-energy neutrinos and high-energy photons, and finally produce GWs. At cosmic distances, only the GWs and the neutrinos remain detectable. In this study, we generalize the argument to starburst and normal galaxies throughout their cosmic evolution and show that these galaxies may dominate over active galactic nuclei (AGN) in the flux of ultra-high-energy particles observed at Earth. All these sources contribute to the cosmic neutrino background, as well as the GW background (they detected lower frequencies). We outline a search strategy to find such episodic sources, which requires including both luminosity and flux density.
{"title":"A two-step strategy to identify episodic sources of gravitational waves and high-energy neutrinos in starburst galaxies","authors":"M. L. Allen, P. L. Biermann, L. Caramete, A. Chieffi, R. Chini, D. Frekers, L. Gergely, B. Harms, I. Jaroschewski, P. S. Joshi, P. P. Kronberg, E. Kun, A. Meli, E.-S. Seo, T. Stanev","doi":"10.3389/fspas.2024.1394741","DOIUrl":"https://doi.org/10.3389/fspas.2024.1394741","url":null,"abstract":"Supermassive black hole (BH) mergers with spin-flips accelerate energetic particles through their relativistic precessing jets, producing high-energy neutrinos and finally gravitational waves (GWs). In star formation, massive stars form in pairs, triplets, and quadruplets, allowing second-generation mergers of the remnants with discrepant spin directions. The GW data support such a scenario. Earlier, we suggested that stellar mass BH mergers (visible in M82) with an associated spin-flip analogously allow the acceleration of energetic particles, with ensuing high-energy neutrinos and high-energy photons, and finally produce GWs. At cosmic distances, only the GWs and the neutrinos remain detectable. In this study, we generalize the argument to starburst and normal galaxies throughout their cosmic evolution and show that these galaxies may dominate over active galactic nuclei (AGN) in the flux of ultra-high-energy particles observed at Earth. All these sources contribute to the cosmic neutrino background, as well as the GW background (they detected lower frequencies). We outline a search strategy to find such episodic sources, which requires including both luminosity and flux density.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":" 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141673243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.3389/fspas.2024.1423545
D. E. da Silva, S. Elkington, X. Li, M. K. Hudson, A. J. Boyd, A. Jaynes, M. Wiltberger
The reprocessing of radiation belt electron flux measurements into phase space density (PSD) as a function of the adiabatic invariants is a widely-used method to address major questions regarding electron energization and loss in the outer radiation belt. In this reprocessing, flux measurements j (α, E) at local pitch angles α, energies E, and optionally magnetometer measurements B, are combined with a global magnetic field model to express the phase space density f (L*) in terms of the third invariant Φ ∝ 1/L* at fixed first and second invariants M and K. While the general framework of the calculation is agreed upon, implementation details vary amongst the literature, and the issue of magnetic field model dependence is rarely addressed. This work reviews the steps of the calculation with lists of commonly used implementation options. For the first time, analysis is presented to display the effect of doing the calculation with different implementation options and with different backing models (including both empirical and MHD-driven models). The results are summarized to inform evaluation of existing results and future efforts calculating and analyzing radiation belt electron phase space density. Three events are analyzed, and while differences are found, the primary structural interpretations of the phase space density analysis exhibit model independence.
{"title":"Radiation belt phase space density: calculation analysis and model dependence","authors":"D. E. da Silva, S. Elkington, X. Li, M. K. Hudson, A. J. Boyd, A. Jaynes, M. Wiltberger","doi":"10.3389/fspas.2024.1423545","DOIUrl":"https://doi.org/10.3389/fspas.2024.1423545","url":null,"abstract":"The reprocessing of radiation belt electron flux measurements into phase space density (PSD) as a function of the adiabatic invariants is a widely-used method to address major questions regarding electron energization and loss in the outer radiation belt. In this reprocessing, flux measurements j (α, E) at local pitch angles α, energies E, and optionally magnetometer measurements B, are combined with a global magnetic field model to express the phase space density f (L*) in terms of the third invariant Φ ∝ 1/L* at fixed first and second invariants M and K. While the general framework of the calculation is agreed upon, implementation details vary amongst the literature, and the issue of magnetic field model dependence is rarely addressed. This work reviews the steps of the calculation with lists of commonly used implementation options. For the first time, analysis is presented to display the effect of doing the calculation with different implementation options and with different backing models (including both empirical and MHD-driven models). The results are summarized to inform evaluation of existing results and future efforts calculating and analyzing radiation belt electron phase space density. Three events are analyzed, and while differences are found, the primary structural interpretations of the phase space density analysis exhibit model independence.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":" 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.3389/fspas.2024.1403154
Marcio Muella, Ana P. M. Silva, Ângela M. dos Santos, V. Pillat, Laysa C. A. Resende, Vânia F. Andrioli, Paulo R. Fagundes
This study investigates the downward motion of Intermediate E-F Layers (ILs) in the Brazilian low latitude sector through observation and modeling. Ionosonde data from São José dos Campos (SJC) and Palmas (PAL) were analyzed to investigate the seasonal variation of the IL parameters, including the virtual height (h'IL) and the top frequency (ftIL). The ILs primarily originated from F layer detachment followed by downward motion, peaking before 11 LT and disappearing well before sunset. Daily height variability ranged between 130 and 190 km, with peak frequencies around 4–5 MHz. Using meteor radar data as input, the Ionospheric E-region Model (MIRE) simulated diurnal and semidiurnal tides to analyze neutral wind effects on ILs descent. Model simulations for SJC (October 2008) and PAL (April and June 2009) revealed distinct wind oscillations influencing IL dynamics at heights below 140 km. In SJC, meridional wind shears controlled IL descent, with possible zonal wind interactions weakening ILs. Conversely, in PAL during April 2009, both zonal and meridional winds contributed to IL formation and altitude descent. However, discrepancies between observed and modeled descent rates suggest the need for considering additional atmospheric wave interactions in future modeling studies. June 2009 over PAL presented unique IL behavior, exhibiting a lower observed decay rate and daily height oscillations potentially linked to local modulations. Meanwhile, MIRE indicated that meridional wind shearing predominantly controlled IL descent in the morning, with zonal wind becoming relevant post-midday. These findings enhance our understanding of IL dynamics and their atmospheric drivers.
本研究通过观测和建模研究了巴西低纬度地区中间层（IL）的向下运动。对圣若泽多斯坎波斯（SJC）和帕尔马斯（PAL）的电离层探测仪数据进行了分析，以研究电离层参数的季节性变化，包括虚拟高度（h'IL）和顶部频率（ftIL）。IL 主要源于 F 层脱离后的向下运动，在 11 时前达到峰值，并在日落前消失。日高度变化范围在 130 至 190 千米之间，峰值频率约为 4-5 兆赫。利用流星雷达数据作为输入，电离层 E 区域模型模拟了昼夜潮汐和半昼夜潮汐，以分析中性风对 ILs 下降的影响。对上海合作组织（2008 年 10 月）和亚太地区（2009 年 4 月和 6 月）的模型模拟显示，在 140 公里以下的高度，影响电离层下降动力学的风振荡截然不同。在 SJC，经向风切变控制着 IL 的下降，可能的地带风相互作用削弱了 IL。相反，2009 年 4 月在 PAL，经向风和带风都对 IL 的形成和高度下降起了作用。然而，观测到的下降率与模拟的下降率之间的差异表明，在未来的模拟研究中需要考虑更多的大气波浪相互作用。2009 年 6 月，PAL 上空出现了独特的 IL 行为，观测到的衰减率较低，每日高度振荡可能与局部调制有关。同时，MIRE 显示，经向风切变在上午主要控制着 IL 的下降，而在中午以后则与带风有关。这些发现加深了我们对IL动力学及其大气驱动因素的理解。
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Pub Date : 2024-07-01DOI: 10.3389/fspas.2024.1401792
Alessandra Corsi, Avery Eddins, T. Lazio, Eric J. Murphy, R. Osten
Compact objects across the mass spectrum–from neutron stars to supermassive black holes–are progenitors and/or central engines for some of the most cataclysmic phenomena in the Universe. As such, they are associated with radio emission on a variety of timescales and represent key targets for multi-messenger astronomy. Observations of transients in the radio band can unveil the physics behind their central engines, ejecta, and the properties of their surroundings, crucially complementing information on their progenitors gathered from observations of other messengers (such as gravitational waves and neutrinos). In this contribution, we summarize observational opportunities and challenges ahead in the multi-messenger study of neutron stars and black holes using radio observations. We highlight the specific contribution of current U.S. national radio facilities and discuss expectations for the field focusing on the science that could be enabled by facilities recommended by the 2020 Decadal survey such as the next generation Very Large Array (ngVLA).
{"title":"Radio transients from compact objects across the mass spectrum in the era of multi-messenger astronomy","authors":"Alessandra Corsi, Avery Eddins, T. Lazio, Eric J. Murphy, R. Osten","doi":"10.3389/fspas.2024.1401792","DOIUrl":"https://doi.org/10.3389/fspas.2024.1401792","url":null,"abstract":"Compact objects across the mass spectrum–from neutron stars to supermassive black holes–are progenitors and/or central engines for some of the most cataclysmic phenomena in the Universe. As such, they are associated with radio emission on a variety of timescales and represent key targets for multi-messenger astronomy. Observations of transients in the radio band can unveil the physics behind their central engines, ejecta, and the properties of their surroundings, crucially complementing information on their progenitors gathered from observations of other messengers (such as gravitational waves and neutrinos). In this contribution, we summarize observational opportunities and challenges ahead in the multi-messenger study of neutron stars and black holes using radio observations. We highlight the specific contribution of current U.S. national radio facilities and discuss expectations for the field focusing on the science that could be enabled by facilities recommended by the 2020 Decadal survey such as the next generation Very Large Array (ngVLA).","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"26 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141699746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.3389/fspas.2024.1390597
Cristian G. Bernal, C. Frajuca, Henrique D. Hirsch, Beatriz Minari, N. Magalhaes, Lucas B. Selbach
In this brief report, we present a model that complements the well-established canonical model for the spin evolution of rotation-powered pulsars, which is typically used to estimate ages, spin-down luminosity, and surface magnetic fields of middle-aged pulsars. We analytically explore the growth of the magnetic field during a pulsar’s early history, a period shortly after supernova explosion from which the neutron star forms, encompassing the hypercritical phase and subsequent reemergence of the magnetic field. We analyze the impact of such growth on the early dynamics of the pulsar. Investigations into a pulsar’s magnetic evolution are not new, and we expand the knowledge in this area by examining the evolutionary implications in a scenario governed by growth functions. The proposed growth functions, calibrated with data from the Crab pulsar, exhibit satisfactory physical behaviors.
{"title":"On the overall properties of young neutron stars: an application to the Crab pulsar","authors":"Cristian G. Bernal, C. Frajuca, Henrique D. Hirsch, Beatriz Minari, N. Magalhaes, Lucas B. Selbach","doi":"10.3389/fspas.2024.1390597","DOIUrl":"https://doi.org/10.3389/fspas.2024.1390597","url":null,"abstract":"In this brief report, we present a model that complements the well-established canonical model for the spin evolution of rotation-powered pulsars, which is typically used to estimate ages, spin-down luminosity, and surface magnetic fields of middle-aged pulsars. We analytically explore the growth of the magnetic field during a pulsar’s early history, a period shortly after supernova explosion from which the neutron star forms, encompassing the hypercritical phase and subsequent reemergence of the magnetic field. We analyze the impact of such growth on the early dynamics of the pulsar. Investigations into a pulsar’s magnetic evolution are not new, and we expand the knowledge in this area by examining the evolutionary implications in a scenario governed by growth functions. The proposed growth functions, calibrated with data from the Crab pulsar, exhibit satisfactory physical behaviors.","PeriodicalId":507437,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"74 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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