Astrophysics and Space Science最新文献_第7页

Wideband polarization and spectral properties of 18 high Galactic latitude pulsars 18 颗银河系高纬度脉冲星的宽带偏振和光谱特性

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-06-07 DOI: 10.1007/s10509-024-04321-7

A. Ahmad, S. Dai, E. Lenc, M. D. Filipović, L. Barnes, G. Hobbs, J. C. F. Balzan, L. Zhang

引用次数: 0

Deep learning-based prediction of CME-driven shock standoff distances in metric type II radio emissions 基于深度学习的公制 II 型射电发射中受 CME 驱动的冲击距离预测

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-06-05 DOI: 10.1007/s10509-024-04319-1

Kwabena Kyeremateng, Amr Hamada, Ahmed Elsaid, Ayman Mahrous

{"title":"Deep learning-based prediction of CME-driven shock standoff distances in metric type II radio emissions","authors":"Kwabena Kyeremateng, Amr Hamada, Ahmed Elsaid, Ayman Mahrous","doi":"10.1007/s10509-024-04319-1","DOIUrl":"10.1007/s10509-024-04319-1","url":null,"abstract":"<div>Type II radio emissions are events mostly found to be associated with coronal mass ejections (CMEs) and accelerated by the CME-driven shock in the heliosphere. This study reports on the estimation of the CME-shock standoff distance at the commencement of metric type II radio emissions by combining the CME-deprojected speed and spectral features of radio bursts using a robust TensorFlow Deep-Learning Sequential (TFDLS) technique. The dataset of 96 CMEs at the commencement of type II radio bursts was used between Solar cycle 24 and the ascending phase of Solar Cycle 25. The measured root mean squared error (RMSE) was 0.145 (Rs), with an average height difference of 0.096 Rs between the observed and predicted CME-shock heights. Five (5) CMEs/radio bursts energetic events associated with solar flares were selected from the test data, and the CME shock stand-off heights were forecasted using the TFDLS and flare-onset (FL) methods. The data were used to compare the leading-edge (LE) and dynamic spectra (DS) methods. The RMSE measured between the FL and LE was 0.35 Rs, and the RMSE estimated between the TFDLS and LE approaches was 0.04 Rs. The RMSE between FL and DS was 0.34. Rs, and the RMSE between the TFDLS and the DS was 0.04 Rs. We also used the findings gained from the five selected events and compared them to the 3D shock-fitting (3D-SF) approach. The RMSE found between the TFDLS and the 3D-SF was 0.18 Rs, while the RMSE estimated between the FL and the 3D-SF was 0.23 Rs. This shows that the TFDLS has satisfactory performance and can be used as an alternative technique.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141398835","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

Analysis of solar energetic particle (SEP) event on the geomagnetic environment during 24th solar cycle 第 24 个太阳周期期间太阳高能粒子（SEP）事件对地磁环境的影响分析

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-06-03 DOI: 10.1007/s10509-024-04320-8

Nirmal Kumar R, Ranjith Dev Inbaseelan C, Karthikeyan E, Nithyasree M, Johnson Jeyakumar H

{"title":"Analysis of solar energetic particle (SEP) event on the geomagnetic environment during 24th solar cycle","authors":"Nirmal Kumar R, Ranjith Dev Inbaseelan C, Karthikeyan E, Nithyasree M, Johnson Jeyakumar H","doi":"10.1007/s10509-024-04320-8","DOIUrl":"10.1007/s10509-024-04320-8","url":null,"abstract":"<div>We report a study of major solar energetic particle (SEP) and ground level enhancement (GLE) events that occurred during the first 62 months of the rising phase of the 24th solar cycle. Our objective is to comprehend the key factors that influence the severity and occurrence of such events. The coronal mass ejection (CME) speed (serves as or is) is a reliable indicator of SEP and GLE events, as it consistently supports the shock acceleration mechanism. Some very fast CMEs, which are likely to have accelerated particles up to GeV energies, may not have resulted in a GLE event due to poor latitudinal connectivity. We have emphasized that the CME speed, magnetic connectivity to Earth, and ambient conditions are the main or primary factors that contribute to the lack of high-energy particle events during cycle 24. Furthermore, we observed that even well-connected fast CMEs that did not seem to have accelerated high-energy particles due to potentially unfavourable prevailing conditions such as high Alfven speed and overall reduction in acceleration efficiency in cycle 24. These conclusions are generally supported by insights gleaned from the observation of the time series of SW-IMF parameters on the flare day.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141254209","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

Centering algorithm of an unresolved primary and satellite system 未解决的主系统和卫星系统的中心定位算法

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-27 DOI: 10.1007/s10509-024-04316-4

J. N. Hao, Q. Y. Peng, B. F. Guo

{"title":"Centering algorithm of an unresolved primary and satellite system","authors":"J. N. Hao, Q. Y. Peng, B. F. Guo","doi":"10.1007/s10509-024-04316-4","DOIUrl":"10.1007/s10509-024-04316-4","url":null,"abstract":"<div>Affected by the Earth’s atmosphere, the image of a primary and satellite system may appear unresolved, such as the dwarf planet Haumea system. It is found by experiments that neither the two-dimensional Gaussian nor modified moment centering algorithms can accurately measure the photocenter of an image of unresolved primary and satellite system observed. This work investigates a specific centering algorithm to accurately measure the photocenter, which would be helpful to derive some physical parameters (e.g. orbital parameters and mass). Taking the dwarf planet Haumea and its brighter satellite Hi’iaka as an example, we simulate the motion of the photocenter with different seeings. We find that the photocenter of system changes significantly with seeings (∼0.074″ with the different seeings of 1″ and 3″) when using the two-dimensional Gaussian centering algorithm. However, the modified moment centering algorithm can accurately measure the photocenter of system without noises, but when noises are added its accuracy will be greatly influenced by noises. In this work, a new centering algorithm is proposed, which can accurately measure the photocenter with less influence of seeings and noises. Observations of dwarf planet Haumea taken over 25 nights are used to test the effectiveness of our proposed method. Compared with using two-dimensional Gaussian centering algorithm, the fitted parameter is slightly more accurate with less positional fitting errors when using the proposed method in this work. This method can also be applied to the centering of binary stars.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141169689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A model on transition between steady states of sub-Keplerian accretion discs: implication for spectral states and hot corona above the disc 亚开普勒吸积盘稳定状态之间的过渡模型：对光谱状态和盘面上方热日冕的影响

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-27 DOI: 10.1007/s10509-024-04318-2

Arunima Ajay, S. R. Rajesh, Nishant K. Singh

引用次数: 0

Two-parametric families of orbits produced by 3D potentials inside a material concentration: an application to galaxy models 物质浓度内三维势能产生的轨道的两参数族：应用于星系模型

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-23 DOI: 10.1007/s10509-024-04313-7

Thomas Kotoulas

{"title":"Two-parametric families of orbits produced by 3D potentials inside a material concentration: an application to galaxy models","authors":"Thomas Kotoulas","doi":"10.1007/s10509-024-04313-7","DOIUrl":"10.1007/s10509-024-04313-7","url":null,"abstract":"<div>We study two-parametric families of spatial orbits given in the analytic form (f(x,y,z)=c_{1}), (g(x,y,z)=c_{2}) ((c_{1}), (c_{2}) = const.) which are produced by three-dimensional potentials (V=V(x,y,z)) inside a material concentration. These potentials must verify two linear partial differential equations (PDEs) which are the basic equations of the 3D Inverse Problem of Newtonian Dynamics and the well-known Poisson’s equation. A suitable class of potentials for this case is the axisymmetric potentials (V=mathcal{B}(x^{2}+y^{2}, z)) which have applications in astrophysical problems. For the given density function (rho =rho (x, y, z)), (rho =rho _{0}=const)., or, (rho =rho (z)) and a pre-assigned family of orbits, three-dimensional potentials producing this family of orbits are found in each case. We focus our interest on the cored, logarithmic potentials and another one of fourth degree describing elliptical galaxies. The two-parametric families of straight lines in 3D space are also considered.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141144126","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

Analytical methods in celestial mechanics: satellites’ stability and galactic billiards 天体力学的分析方法：卫星稳定性和银河系台球

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-23 DOI: 10.1007/s10509-024-04312-8

Irene De Blasi

{"title":"Analytical methods in celestial mechanics: satellites’ stability and galactic billiards","authors":"Irene De Blasi","doi":"10.1007/s10509-024-04312-8","DOIUrl":"10.1007/s10509-024-04312-8","url":null,"abstract":"<div>In this paper, two models of interest for Celestial Mechanics are presented and analysed, using both analytic and numerical techniques, from the point of view of the possible presence of regular and/or chaotic motion, as well as the stability of the considered orbits. The first model, presented in a Hamiltonian formalism, can be used to describe the motion of a satellite around Earth, taking into account both the non-spherical shape of our planet and the third-body gravitational influence of Sun and Moon. Using semi-analytical techniques coming from Normal Form and Nekhoroshev theories it is possible to provide stability estimates for the orbital elements of its geocentric motion. The second dynamical system presented can be used as a simplified model to describe the motion of a particle in an elliptic galaxy having a central massive core; it is constructed as a refraction billiard where an inner dynamics, induced by a Keplerian potential, is coupled with an external one, where a harmonic oscillator-type potential is considered. The investigation of the dynamics is carried on by using results of ODEs’ theory and is focused on studying the trajectories’ properties in terms of periodicity, stability and, possibly, chaoticity.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-024-04312-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141153295","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

Comparative analysis of the parameters of pulsars with braking indices (n>0) and (n<0) 制动指数为 $n>0$ 和 $n<0$ 的脉冲星参数对比分析

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-22 DOI: 10.1007/s10509-024-04317-3

C. C. Onuchukwu, E. Legahara

{"title":"Comparative analysis of the parameters of pulsars with braking indices (n>0) and (n<0)","authors":"C. C. Onuchukwu, E. Legahara","doi":"10.1007/s10509-024-04317-3","DOIUrl":"10.1007/s10509-024-04317-3","url":null,"abstract":"<div>We analyzed the timing parameters (the rotational frequency (nu ), the first (left ( dot{nu } right )) and second (left ( ddot{nu } right )) time-derivatives of frequency) and the derived parameters of a sample of pulsars for which (ddot{nu } ) (470 pulsars) were recorded in the Australian Telescope National Facility (ATNF) pulsar catalog. We formed various subsamples, those with braking indices (n<0) and (n>0), and glitching and non-glitching pulsars. Our statistical analyses of the timing and derived parameters indicated some level of differences and similarities among the parameters analyzed. Glitching pulsars appear to have a higher rotational frequency than non-glitching pulsars, and pulsars with (n>0) appear to rotate faster than those with (n<0). Our results also suggest that glitching pulsars have lower values of (left vert n right vert ) (where (left vert n right vert ) is the absolute value of the braking index), and it is lower for the subsample with (n>0) than for the subsample with (n<0). We believe that the results obtained could be useful in understanding the evolution of pulsar spin.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141145021","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

Cosmological dynamics of accelerating model in (f(Q)) gravity with latest observational data 加速模型在 $f(Q)$ 引力下的宇宙动力学与最新观测数据

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-21 DOI: 10.1007/s10509-024-04315-5

Vinod Kumar Bhardwaj, Priyanka Garg, Suraj Prakash

{"title":"Cosmological dynamics of accelerating model in (f(Q)) gravity with latest observational data","authors":"Vinod Kumar Bhardwaj, Priyanka Garg, Suraj Prakash","doi":"10.1007/s10509-024-04315-5","DOIUrl":"10.1007/s10509-024-04315-5","url":null,"abstract":"<div>In the current study, we have considered three different parameterizations of deceleration parameter to describe the cosmological dynamics of the accelerating universe in (f(Q)) gravity. The power law symmetric teleparallel gravity with a specific form (f(Q)= Q + n Q^{m}) is assumed for the modelling purpose. Here, (m) and (n) are constants and (Q) is the non-metricity term that describes the gravitational interaction in space time. We constructed the field equations depending on the power law (f(Q)) gravity and parameters are extracted using experimental observations. Latest observational datasets of BAO, (H(z)) and Pantheon are utilized to predict the best fit values of parameters and current value of Hubble constant. The Markov Chain Monte Carlo (MCMC) algorithm has been used to decide the best plausible values of parameters. We numerically represent the physical and geometrical features of the models and thoroughly explore their development. We analyzed our models using the jerk and Om diagnosis that depict the derived cosmic models are different from the (Lambda )CDM model expressing late time accelerated expansion of cosmos with phantom type of the universe. We also discussed the viability of models by the analysis of energy conditions.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141130183","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

Revisiting short-plateau SN 2018gj 重温短高原SN 2018gj

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2024-05-17 DOI: 10.1007/s10509-024-04311-9

V. P. Utrobin, N. N. Chugai

{"title":"Revisiting short-plateau SN 2018gj","authors":"V. P. Utrobin, N. N. Chugai","doi":"10.1007/s10509-024-04311-9","DOIUrl":"10.1007/s10509-024-04311-9","url":null,"abstract":"<div>We present an alternative model of unusual type-IIP SN 2018gj. Despite the short plateau and early gamma-ray escape seeming to favor low-mass ejecta, our hydrodynamic model requires a large ejected mass (≈23 (M_{odot })). The high ejecta velocity, we find from hydrogen lines in early spectra, is among the crucial constraints on the hydrodynamic model. We recover the wind density that rules out a notable contribution of the circumstellar interaction to the bolometric luminosity. The early radioactive gamma-ray escape is found to be due to the high velocity of 56Ni, whereas the asymmetry of the H(alpha ) emission is attributed to the asymmetry of the 56Ni ejecta. The available sample of type-IIP supernovae studied hydrodynamically in a uniform way indicates that the asymmetry of the 56Ni ejecta is probably their intrinsic property. Hydrogen lines in the early spectra of SN 2018gi and SN 2020jfo are found to imply a clumpy structure of the outer ejecta. With two already known similar cases of SN 2008in and SN 2012A we speculate that the clumpiness of the outer ejecta is inherent to type-IIP supernovae related to the red supergiant explosion.</div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"369 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141045251","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