Advances in Astronomy最新文献_第3页

Analysis of ∼106 Spiral Galaxies from Four Telescopes Shows Large-Scale Patterns of Asymmetry in Galaxy Spin Directions 从四台望远镜对~ 106个螺旋星系的分析显示了星系自旋方向的大规模不对称模式

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2022-05-31 DOI: 10.1155/2022/8462363

L. Shamir

{"title":"Analysis of ∼106 Spiral Galaxies from Four Telescopes Shows Large-Scale Patterns of Asymmetry in Galaxy Spin Directions","authors":"L. Shamir","doi":"10.1155/2022/8462363","DOIUrl":"https://doi.org/10.1155/2022/8462363","url":null,"abstract":"The ability to collect unprecedented amounts of astronomical data has enabled the nomical data has enabled the stu scientific questions that were impractical to study in the pre-information era. This study uses large datasets collected by four different robotic telescopes to profile the large-scale distribution of the spin directions of spiral galaxies. These datasets cover the Northern and Southern hemispheres, in addition to data acquired from space by the Hubble Space Telescope. The data were annotated automatically by a fully symmetric algorithm, as well as manually through a long labor-intensive process, leading to a dataset of nearly \u0000 \u0000 \u0000 \u0000 10\u0000 \u0000 \u0000 6\u0000 \u0000 \u0000 \u0000 galaxies. The data show possible patterns of asymmetric distribution of the spin directions, and the patterns agree between the different telescopes. The profiles also agree when using automatic or manual annotation of the galaxies, showing very similar large-scale patterns. Combining all data from all telescopes allows the most comprehensive analysis of its kind to date in terms of both the number of galaxies and the footprint size. The results show a statistically significant profile that is consistent across all telescopes. The instruments used in this study are DECam, HST, SDSS, and Pan-STARRS. The paper also discusses possible sources of bias and analyzes the design of previous work that showed different results. Further research will be required to understand and validate these preliminary observations.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46098161","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: 6

Existential Properties of Algebraic Integrals of a Rigid Body 刚体代数积分的存在性

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2022-04-22 DOI: 10.1155/2022/9393658

A. I. Ismail, W. Amer

引用次数: 1

Testing Correspondence between Areas with Hydrated Minerals, as Observed by CRISM/MRO, and Spots of Enhanced Subsurface Water Content, as Found by DAN along the Traverse of Curiosity 测试CRISM/MRO观测到的具有水合矿物的区域与DAN沿好奇号穿越线发现的地下含水量增加的点之间的对应关系

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2022-04-01 DOI: 10.1155/2022/6672456

M. Djachkova, I. Mitrofanov, S. Nikiforov, D. Lisov, M. Litvak, A. Sanin

{"title":"Testing Correspondence between Areas with Hydrated Minerals, as Observed by CRISM/MRO, and Spots of Enhanced Subsurface Water Content, as Found by DAN along the Traverse of Curiosity","authors":"M. Djachkova, I. Mitrofanov, S. Nikiforov, D. Lisov, M. Litvak, A. Sanin","doi":"10.1155/2022/6672456","DOIUrl":"https://doi.org/10.1155/2022/6672456","url":null,"abstract":"Possible correlation is studied between Water Equivalent Hydrogen (WEH) in the Martian subsurface, as measured by the DAN (Dynamic Albedo of Neutrons) instrument along the Curiosity traverse, and the presence of hydrated minerals on the surface, as seen from the orbit by CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument onboard MRO (Mars Reconnaissance Orbiter). Cross-analysis of the subsurface WEH values from DAN passive measurements with the distribution of hydrated minerals over the surface of Gale crater according to Specialized Browse Product Mosaics is performed for the initial 20 km part of traverse. As a result, we found an increase up to 0.4 wt% of the mean WEH value for the surface areas with the spectral signatures of polyhydrated sulfates. The increase is shown to be higher with the more prominent spectral signature on the surface. Similar WEH increase for the two other types of hydrated minerals, such as monohydrated sulfates and phyllosilicates, was not found for the tested part of the traverse. Polyhydrated sulfates being a part of the sedimentary deposits composing the surface of Gale crater should have considerable thickness that is necessary for the subsurface neutron sensing by DAN measurements.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":"1 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43482937","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: 2

Artificial Triangular Points by Lorentz Force in the Restricted Three-Body Problem 受限三体问题中的洛伦兹力人工三角点

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2022-03-22 DOI: 10.1155/2022/4157792

A. Mostafa, M. A. Yousef, M. El-Saftawy

引用次数: 3

Automated Stellar Spectra Classification with Ensemble Convolutional Neural Network 基于集成卷积神经网络的恒星光谱自动分类

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2022-01-04 DOI: 10.1155/2022/4489359

Zhuang Zhao, Jiyu Wei, Bin Jiang

{"title":"Automated Stellar Spectra Classification with Ensemble Convolutional Neural Network","authors":"Zhuang Zhao, Jiyu Wei, Bin Jiang","doi":"10.1155/2022/4489359","DOIUrl":"https://doi.org/10.1155/2022/4489359","url":null,"abstract":"Large sky survey telescopes have produced a tremendous amount of astronomical data, including spectra. Machine learning methods must be employed to automatically process the spectral data obtained by these telescopes. Classification of stellar spectra by applying deep learning is an important research direction for the automatic classification of high-dimensional celestial spectra. In this paper, a robust ensemble convolutional neural network (ECNN) was designed and applied to improve the classification accuracy of massive stellar spectra from the Sloan digital sky survey. We designed six classifiers which consist six different convolutional neural networks (CNN), respectively, to recognize the spectra in DR16. Then, according the cross-entropy testing error of the spectra at different signal-to-noise ratios, we integrate the results of different classifiers in an ensemble learning way to improve the effect of classification. The experimental result proved that our one-dimensional ECNN strategy could achieve 95.0% accuracy in the classification task of the stellar spectra, a level of accuracy that exceeds that of the classical principal component analysis and support vector machine model.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47891325","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: 2

Brine-Induced Tribocorrosion Accelerates Wear on Stainless Steel: Implications for Mars Exploration 盐水引发的摩擦腐蚀加速不锈钢磨损：对火星探测的启示

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2021-12-28 DOI: 10.1155/2021/6441233

J. Martín‐Torres, M. Zorzano‐Mier, E. Nyberg, A. Vakkada-Ramachandran, A. Bhardwaj

引用次数: 1

Modeling of the Dark Phase of Flight and the Impact Area for Meteorites of Real Shapes 真实形状陨石飞行暗相和撞击区域的建模

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2021-12-23 DOI: 10.1155/2021/5530540

Karol Havrila, J. Tóth, L. Kornoš

{"title":"Modeling of the Dark Phase of Flight and the Impact Area for Meteorites of Real Shapes","authors":"Karol Havrila, J. Tóth, L. Kornoš","doi":"10.1155/2021/5530540","DOIUrl":"https://doi.org/10.1155/2021/5530540","url":null,"abstract":"Aims. The complex dynamics of bodies, originating from the interplanetary matter and passing through Earth’s atmosphere, defines their further position, velocity, and final location on Earth’s surface in the form of meteorites. One of the important factors that affect the movement of a body in the atmosphere is its shape and orientation. Our goal is to model the interaction of real shape meteoroids with Earth’s atmosphere and compare the results with the standard spherical body approach. Methods. In the simulation, we use 3D models of fragments of the Košice meteorite with different sizes and shapes. Using a 3D model of fragments, we consider the real shape of the body to define its resistance properties during atmospheric transition more specifically. The simulation is performed using virtual wind tunnel in the MicroCFD (Computational Fluid Dynamics) software to obtain more realistic drag coefficients and using the µ(m)-Trajectory software to model the particle trajectory in the atmosphere including the wind profile. The final outputs from these programs are the drag coefficient as a function of the altitude and the particle orientation. Using these parameters we get the more realistic body trajectory and the impact area coordinates. Comparison of the results for real and spherical model meteorite impact location is discussed. Results. Simulation showed significant differences in trajectory and the impact area for the different real body orientations compared to the spherically symmetric body. Also, an important result is a difference in the impact area of the real body with a specific orientation without rotation and the body with considered rotation. The significant difference between the modeled impact of a real shape body and its real place of finding compared to a spherically symmetric body indicates the importance of the method used.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42237017","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: 1

Predicting Pulsars from Imbalanced Dataset with Hybrid Resampling Approach 利用混合重采样方法预测不平衡数据集中的脉冲星

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2021-12-03 DOI: 10.1155/2021/4916494

Ernesto Lee, F. Rustam, Wajdi Aljedaani, Abid Ishaq, Vaibhav Rupapara, I. Ashraf

{"title":"Predicting Pulsars from Imbalanced Dataset with Hybrid Resampling Approach","authors":"Ernesto Lee, F. Rustam, Wajdi Aljedaani, Abid Ishaq, Vaibhav Rupapara, I. Ashraf","doi":"10.1155/2021/4916494","DOIUrl":"https://doi.org/10.1155/2021/4916494","url":null,"abstract":"Pulsar stars, usually neutron stars, are spherical and compact objects containing a large quantity of mass. Each pulsar star possesses a magnetic field and emits a slightly different pattern of electromagnetic radiation which is used to identify the potential candidates for a real pulsar star. Pulsar stars are considered an important cosmic phenomenon, and scientists use them to study nuclear physics, gravitational waves, and collisions between black holes. Defining the process of automatic detection of pulsar stars can accelerate the study of pulsar stars by scientists. This study contrives an accurate and efficient approach for true pulsar detection using supervised machine learning. For experiments, the high time-resolution (HTRU2) dataset is used in this study. To resolve the data imbalance problem and overcome model overfitting, a hybrid resampling approach is presented in this study. Experiments are performed with imbalanced and balanced datasets using well-known machine learning algorithms. Results demonstrate that the proposed hybrid resampling approach proves highly influential to avoid model overfitting and increase the prediction accuracy. With the proposed hybrid resampling approach, the extra tree classifier achieves a 0.993 accuracy score for true pulsar star prediction.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41907955","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: 5

Subsurface Thermal Modeling of Oxia Planum, Landing Site of ExoMars 2022 ExoMars 2022着陆点的缺氧平原地下热模拟

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2021-09-01 DOI: 10.1155/2021/9924571

M. Formisano, M. D. De Sanctis, C. Federico, G. Magni, F. Altieri, E. Ammannito, S. De Angelis, M. Ferrari, A. Frigeri

引用次数: 3

Periodic Variation of Solar Flare Index for the Last Solar Cycle (Cycle 24) 最后一个太阳周期(第24周期)太阳耀斑指数的周期变化

IF 1.4 4区物理与天体物理

Advances in Astronomy Pub Date : 2021-08-23 DOI: 10.1155/2021/5391091

A. Ozguc, A. Kilçik, V. Sarp, H. Yeşilyaprak, R. Pektaş

{"title":"Periodic Variation of Solar Flare Index for the Last Solar Cycle (Cycle 24)","authors":"A. Ozguc, A. Kilçik, V. Sarp, H. Yeşilyaprak, R. Pektaş","doi":"10.1155/2021/5391091","DOIUrl":"https://doi.org/10.1155/2021/5391091","url":null,"abstract":"In this study, we used the flare index (FI) data taken from Kandilli Observatory for the period of 2009–2020. The data sets are analyzed in three categories as Northern Hemisphere, Southern Hemisphere, and total FI data sets. Total FI data set is obtained from the sum of Northern and Southern Hemispheric values. In this study, the periodic variations of abovementioned three categories FI data sets were investigated by using the MTM and Morlet wavelet analysis methods. The wavelet coherence (XWT) and cross wavelet (WTC) analysis methods were also performed between these data sets. As a result of our analysis, the following results were found: (1) long- and short-term periodicities (\u0000 \u0000 2048\u0000 ±\u0000 512\u0000 \u0000 day and periodicities smaller than 62 days) exist in all data sets without any exception at least with \u0000 \u0000 95\u0000 %\u0000 \u0000 confidence level; (2) all periodic variations were detected maximum during the solar cycle, while during the minima, no meaningful period is detected; (3) some periodicities have data preference that about 150 days Rieger period appears only in the whole data set and 682-, 204-, and 76.6-day periods appear only in the Northern Hemisphere data sets; (4) During the Solar Cycle 24, more flare activity is seen at the Southern Hemisphere, so the whole disk data periodicities are dominated by this hemisphere; (5) in general, there is a phase mixing between Northern and Southern Hemisphere FI data, except about 1024-day periodicity, and the best phase coherency is obtained between the Southern Hemisphere and total flare index data sets; (6) in case of the Northern and Southern Hemisphere FI data sets, there is no significant correlation between two continuous wavelet transforms, but the strongest correlation is obtained for the total FI and Southern Hemisphere data sets.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41397312","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: 5