Pub Date : 2022-01-01DOI: 10.51194/vak2021.2022.1.1.045
N. Kargaltseva, S. Khaibrakhmanov, A. Dudorov, S. Zamozdra, A. Zhilkin
Abstract We numerically model the collapse of magnetic rotating protostellar clouds with mass of 10 M ⊙ {M}_{odot } . The simulations are carried out with the help of 2D MHD code Enlil. The structure of the cloud at the isothermal stage of the collapse is investigated for the cases of weak, moderate, and strong initial magnetic field. Simulations reveal the universal hierarchical structure of collapsing protostellar clouds, consisting of the flattened envelope with the qausi-magnetostatc disk inside and the first core in its center. The size of the primary disk increases with the initial magnetic energy of the cloud. The magnetic braking efficiently transports the angular momentum from the primary disk into the envelope in the case, when the initial magnetic energy of the cloud is more than 20% of its gravitational energy. The intensity of the outflows launched from the region near the boundary of the first core increases with initial magnetic energy. The “dead” zone with small ionization fraction, x < 1 0 − 11 xlt 1{0}^{-11} , forms inside the first hydrostatic core and at the base of the outflow. Ohmic dissipation and ambipolar diffusion determine conditions for further formation of the protostellar disk in this region.
{"title":"Influence of the magnetic field on the formation of protostellar disks","authors":"N. Kargaltseva, S. Khaibrakhmanov, A. Dudorov, S. Zamozdra, A. Zhilkin","doi":"10.51194/vak2021.2022.1.1.045","DOIUrl":"https://doi.org/10.51194/vak2021.2022.1.1.045","url":null,"abstract":"Abstract We numerically model the collapse of magnetic rotating protostellar clouds with mass of 10 M ⊙ {M}_{odot } . The simulations are carried out with the help of 2D MHD code Enlil. The structure of the cloud at the isothermal stage of the collapse is investigated for the cases of weak, moderate, and strong initial magnetic field. Simulations reveal the universal hierarchical structure of collapsing protostellar clouds, consisting of the flattened envelope with the qausi-magnetostatc disk inside and the first core in its center. The size of the primary disk increases with the initial magnetic energy of the cloud. The magnetic braking efficiently transports the angular momentum from the primary disk into the envelope in the case, when the initial magnetic energy of the cloud is more than 20% of its gravitational energy. The intensity of the outflows launched from the region near the boundary of the first core increases with initial magnetic energy. The “dead” zone with small ionization fraction, x < 1 0 − 11 xlt 1{0}^{-11} , forms inside the first hydrostatic core and at the base of the outflow. Ohmic dissipation and ambipolar diffusion determine conditions for further formation of the protostellar disk in this region.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"172 - 180"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49085987","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}
Pub Date : 2022-01-01DOI: 10.51194/vak2021.2022.1.1.048
S. Khaibrakhmanov, A. Dudorov
Abstract The dynamics of magnetic flux tubes (MFTs) in the accretion disk of typical Herbig Ae/Be star (HAeBeS) with fossil large-scale magnetic field is modeled taking into account the buoyant and drag forces, radiative heat exchange with the surrounding gas, and the magnetic field of the disk. The structure of the disk is simulated using our magnetohydrodynamic model, taking into account the heating of the surface layers of the disk with the stellar radiation. The simulations show that MFTs periodically rise from the innermost region of the disk with speeds up to 10–12 km s − 1 {{rm{s}}}^{-1} . MFTs experience decaying magnetic oscillations under the action of the external magnetic field near the disk’s surface. The oscillation period increases with distance from the star and initial plasma beta of the MFT, ranging from several hours at r = 0.012 au r=0.012hspace{0.33em}{rm{au}} up to several months at r = 1 au r=1hspace{0.33em}{rm{au}} . The oscillations are characterized by pulsations of the MFT’s characteristics including its temperature. We argue that the oscillations can produce observed IR-variability of HAeBeSs, which would be more intense than in the case of T Tauri stars, since the disks of HAeBeSs are hotter, denser, and have stronger magnetic field.
摘要考虑浮力和阻力、与周围气体的辐射热交换以及吸积盘中的磁场，对典型赫比格Ae/Be星（HAeBeS）在化石大尺度磁场下吸积盘中磁通管的动力学进行了建模。考虑到恒星辐射对磁盘表层的加热，使用我们的磁流体动力学模型模拟了磁盘的结构。模拟表明，MFT从磁盘的最内部区域周期性地上升，速度高达10–12 km s−1｛rm｛s｝｝}^｛-1｝。MFT在磁盘表面附近的外部磁场的作用下经历衰减的磁振荡。振荡周期随着与恒星的距离和MFT的初始等离子体β的增加而增加，从r＝0.012 au r＝0.012hspace｛0.33em｝的几个小时到r＝1 au r＝1hspace｛｛0.33em｝｛rm｛au｝的几个月。振荡的特征是MFT特性的脉动，包括其温度。我们认为，振荡可以产生观测到的HAeBeS的IR变化，这将比金牛座T星的情况更强烈，因为HAeBeSs的圆盘更热、更致密，并且具有更强的磁场。
{"title":"Dynamics of magnetic flux tubes in accretion disks of Herbig Ae/Be stars","authors":"S. Khaibrakhmanov, A. Dudorov","doi":"10.51194/vak2021.2022.1.1.048","DOIUrl":"https://doi.org/10.51194/vak2021.2022.1.1.048","url":null,"abstract":"Abstract The dynamics of magnetic flux tubes (MFTs) in the accretion disk of typical Herbig Ae/Be star (HAeBeS) with fossil large-scale magnetic field is modeled taking into account the buoyant and drag forces, radiative heat exchange with the surrounding gas, and the magnetic field of the disk. The structure of the disk is simulated using our magnetohydrodynamic model, taking into account the heating of the surface layers of the disk with the stellar radiation. The simulations show that MFTs periodically rise from the innermost region of the disk with speeds up to 10–12 km s − 1 {{rm{s}}}^{-1} . MFTs experience decaying magnetic oscillations under the action of the external magnetic field near the disk’s surface. The oscillation period increases with distance from the star and initial plasma beta of the MFT, ranging from several hours at r = 0.012 au r=0.012hspace{0.33em}{rm{au}} up to several months at r = 1 au r=1hspace{0.33em}{rm{au}} . The oscillations are characterized by pulsations of the MFT’s characteristics including its temperature. We argue that the oscillations can produce observed IR-variability of HAeBeSs, which would be more intense than in the case of T Tauri stars, since the disks of HAeBeSs are hotter, denser, and have stronger magnetic field.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"125 - 135"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45148257","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}
Na Fu, Guanghua Zhang, Keqiang Xia, Kun Qu, Guan Wu, M. Han, Junru Duan
Abstract Satellite anomaly is a process of evolution. Detecting this evolution and the underlying feature changes is critical to satellite health prediction, fault early warning, and response. Analyzing the correlation between telemetry parameters is more convincing than detecting single-point anomalies. In this article, principal component analysis method was adopted to downscale the multivariate probability model, T 2 {T}^{2} statistic was checked to determine the data anomaly, without the trouble of threshold setting. After an anomaly was detected, time-domain visualization and dimension reduction methods were introduced to visualize the satellite anomaly evolution, where the dimensions of telemetry or features were reduced and presented in two- or three-dimensional coordinates. Engineering practice shows that this method facilitates the early detection of satellite anomalies, and helps ground operators to respond in the early stages of an anomaly.
{"title":"Research on fault detection and principal component analysis for spacecraft feature extraction based on kernel methods","authors":"Na Fu, Guanghua Zhang, Keqiang Xia, Kun Qu, Guan Wu, M. Han, Junru Duan","doi":"10.1515/astro-2022-0194","DOIUrl":"https://doi.org/10.1515/astro-2022-0194","url":null,"abstract":"Abstract Satellite anomaly is a process of evolution. Detecting this evolution and the underlying feature changes is critical to satellite health prediction, fault early warning, and response. Analyzing the correlation between telemetry parameters is more convincing than detecting single-point anomalies. In this article, principal component analysis method was adopted to downscale the multivariate probability model, T 2 {T}^{2} statistic was checked to determine the data anomaly, without the trouble of threshold setting. After an anomaly was detected, time-domain visualization and dimension reduction methods were introduced to visualize the satellite anomaly evolution, where the dimensions of telemetry or features were reduced and presented in two- or three-dimensional coordinates. Engineering practice shows that this method facilitates the early detection of satellite anomalies, and helps ground operators to respond in the early stages of an anomaly.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"333 - 339"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47245519","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}
Abstract Eclipses of UX Ori stars by compact gas–dust clouds and large-scale circumstellar disk perturbations are modeled. A flared disk and a disk with a puffing-up in the dust sublimation zone are considered. The disk puffing-up explains several observed features of eclipses. The linear polarization degree can remain unchanged during the eclipse. There might be no star reddening in the blue and ultraviolet spectral regions. Strong changes (up to 90 ° 90text{°} ) in the positional angle of the linear polarization may happen when passing from one spectral band to another. An eclipse by a large-scale disk perturbation can be noticeably deeper than an eclipse by a compact gas–dust cloud. The polarization degree in such an eclipse can also be significantly higher. In addition, an eclipse by a large-scale perturbation of a star with a puffed-up disk explains the significant scatter of eclipse parameters at the same fading level. A significant change in the positional angle of the linear polarization may occur during a large-scale disk perturbation eclipse minimum and after it. We attempted parametric identification of long-lasted deep minima of UX Ori and WW Vul. The considered simple model can only partially explain the observed phenomena and need further development.
{"title":"Modeling of large-scale disk perturbation eclipses of UX Ori stars with the puffed-up inner disks","authors":"Sergey Shulman, V. Grinin","doi":"10.1515/astro-2022-0010","DOIUrl":"https://doi.org/10.1515/astro-2022-0010","url":null,"abstract":"Abstract Eclipses of UX Ori stars by compact gas–dust clouds and large-scale circumstellar disk perturbations are modeled. A flared disk and a disk with a puffing-up in the dust sublimation zone are considered. The disk puffing-up explains several observed features of eclipses. The linear polarization degree can remain unchanged during the eclipse. There might be no star reddening in the blue and ultraviolet spectral regions. Strong changes (up to 90 ° 90text{°} ) in the positional angle of the linear polarization may happen when passing from one spectral band to another. An eclipse by a large-scale disk perturbation can be noticeably deeper than an eclipse by a compact gas–dust cloud. The polarization degree in such an eclipse can also be significantly higher. In addition, an eclipse by a large-scale perturbation of a star with a puffed-up disk explains the significant scatter of eclipse parameters at the same fading level. A significant change in the positional angle of the linear polarization may occur during a large-scale disk perturbation eclipse minimum and after it. We attempted parametric identification of long-lasted deep minima of UX Ori and WW Vul. The considered simple model can only partially explain the observed phenomena and need further development.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"67 - 79"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44890233","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}
Abstract Based on the characteristics of near-circular orbits and close-range leader–follower flights, the relative dynamics equations of the eccentricity/inclination ( e/i ) vector method are introduced herein. Additionally, the constraint terms in the design of the leader–follower flight formation are found to satisfy the conditions of the line-of-sight angle and inter-satellite distance. The control box algorithm is proposed under the flying task’s constraints, such as the line-of-sight angle and distance between the satellites according to the e/i vector and Gauss perturbation equations. The algorithm comprehensively takes into account the relationship between the relative motion variations in the satellite formation in near-circular orbits as well as their relationship with the velocity increment applied to the satellites. The example simulated in this study not only illustrates the existence of a coupling relationship between the flight-following distance and flight-following line-of-sight angle but also verifies the influence of the relative eccentricity of the two satellites on the leader–follower flight stability. The simulation results show that when the control box algorithm was used to maintain the leader–follower flight, this method was simple, intuitive, and may be feasibly introduced as a flight-following control strategy.
{"title":"Close-range leader–follower flight control technology for near-circular low-orbit satellites","authors":"Yuan Yang, Heng-nian Li, Yikang Yang, Chongyuan Hou, Kaijian Zhu","doi":"10.1515/astro-2022-0032","DOIUrl":"https://doi.org/10.1515/astro-2022-0032","url":null,"abstract":"Abstract Based on the characteristics of near-circular orbits and close-range leader–follower flights, the relative dynamics equations of the eccentricity/inclination ( e/i ) vector method are introduced herein. Additionally, the constraint terms in the design of the leader–follower flight formation are found to satisfy the conditions of the line-of-sight angle and inter-satellite distance. The control box algorithm is proposed under the flying task’s constraints, such as the line-of-sight angle and distance between the satellites according to the e/i vector and Gauss perturbation equations. The algorithm comprehensively takes into account the relationship between the relative motion variations in the satellite formation in near-circular orbits as well as their relationship with the velocity increment applied to the satellites. The example simulated in this study not only illustrates the existence of a coupling relationship between the flight-following distance and flight-following line-of-sight angle but also verifies the influence of the relative eccentricity of the two satellites on the leader–follower flight stability. The simulation results show that when the control box algorithm was used to maintain the leader–follower flight, this method was simple, intuitive, and may be feasibly introduced as a flight-following control strategy.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"366 - 374"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43770762","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}
Abstract This article presents a study on the design of high-speed inter-satellite links for the global navigation satellite system, which consists of 24 middle earth orbit, 3 inclined geosynchronous orbit, 3 geostationary orbit satellites, and 4 typical ground stations based on the laser link of slowly varying continuous system and high-speed Ka link. Pre-allocation of node connections in inter-satellite link construction is conducted by employing the optimized Dijkstra algorithm using finite-state automata. In addition, topological design and routing planning principles are utilized for high-speed inter-satellite links. Based on full constellation orbit data of a regression period and locations of the ground station nodes, an hourly link construction program is obtained using the scheme described above. The calculation result of the position dilution of precision values of all satellites, the average inter-satellite transmission delay, and the inter-satellite link switching meet the requirements of measurement, data transmission, and management for navigation constellation.
{"title":"High-speed inter-satellite link construction technology for navigation constellation oriented to engineering practice","authors":"Canyou Liu, Feng Zhang, Hao-Yang Ma, Shuang Chen, Xin Wang, Xiusong Ye","doi":"10.1515/astro-2022-0199","DOIUrl":"https://doi.org/10.1515/astro-2022-0199","url":null,"abstract":"Abstract This article presents a study on the design of high-speed inter-satellite links for the global navigation satellite system, which consists of 24 middle earth orbit, 3 inclined geosynchronous orbit, 3 geostationary orbit satellites, and 4 typical ground stations based on the laser link of slowly varying continuous system and high-speed Ka link. Pre-allocation of node connections in inter-satellite link construction is conducted by employing the optimized Dijkstra algorithm using finite-state automata. In addition, topological design and routing planning principles are utilized for high-speed inter-satellite links. Based on full constellation orbit data of a regression period and locations of the ground station nodes, an hourly link construction program is obtained using the scheme described above. The calculation result of the position dilution of precision values of all satellites, the average inter-satellite transmission delay, and the inter-satellite link switching meet the requirements of measurement, data transmission, and management for navigation constellation.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"348 - 356"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41487017","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}
Gang Chen, Xin Tong, Weibing Du, Jing-rui Zhao, Hanyong Zhang
Abstract The basic concepts, technical implementation, and application scenarios of computer simulation, virtualization, and cloud computing are intertwined and each has its characteristics. In this article, the basic concepts, necessity, feasibility, and core difficulties of computer simulation, virtualization, and cloud computing are analyzed. Also, the application prospects of the three technologies are expounded, the technical differences are analyzed, and the application of some key technologies in the data center is introduced. The generalization of computer simulation technology, the specialization of virtualization technology, and the systematization of cloud computing technology are expounded, which represent the mainstream direction of technology development in the field of information and communication at this stage. The application examples of the three in the aerospace telemetry, tracking, and command field are taken to illustrate that information technology essentially serves the business logic of their respective fields, which also well reflects the basic characteristics of demand-oriented, safety-oriented, innovation, and long-term development. It has guiding significance for the technical orientation, technical selection, and engineering implementation of information system architecture design.
{"title":"Application of cloud computing key technology in aerospace TT&C","authors":"Gang Chen, Xin Tong, Weibing Du, Jing-rui Zhao, Hanyong Zhang","doi":"10.1515/astro-2022-0029","DOIUrl":"https://doi.org/10.1515/astro-2022-0029","url":null,"abstract":"Abstract The basic concepts, technical implementation, and application scenarios of computer simulation, virtualization, and cloud computing are intertwined and each has its characteristics. In this article, the basic concepts, necessity, feasibility, and core difficulties of computer simulation, virtualization, and cloud computing are analyzed. Also, the application prospects of the three technologies are expounded, the technical differences are analyzed, and the application of some key technologies in the data center is introduced. The generalization of computer simulation technology, the specialization of virtualization technology, and the systematization of cloud computing technology are expounded, which represent the mainstream direction of technology development in the field of information and communication at this stage. The application examples of the three in the aerospace telemetry, tracking, and command field are taken to illustrate that information technology essentially serves the business logic of their respective fields, which also well reflects the basic characteristics of demand-oriented, safety-oriented, innovation, and long-term development. It has guiding significance for the technical orientation, technical selection, and engineering implementation of information system architecture design.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"217 - 228"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46156209","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}
Min Zhai, Zongbo Huyan, Yuanyuan Hu, Yu Jiang, H. Li
Abstract High-accuracy orbit prediction plays a crucial role in several aerospace applications, such as satellite navigation, orbital maneuver, space situational awareness, etc. The conventional methods of orbit prediction are usually based on dynamic models with clear mathematical expressions. However, coefficients of perturbation forces and relevant features of satellites are approximate values, which induces errors during the process of orbit prediction. In this study, a new orbit prediction model based on principal component analysis (PCA) and extreme gradient boosting (XGBoost) model is proposed to improve the accuracy of orbit prediction by learning from the historical data in a simulated environment. First, a series of experiments are conducted to determine the approximate numbers of features, which are used in the following machine learning (ML) process. Then, PCA and XGBoost models are used to find incremental corrections to orbit prediction with dynamic models. The results reveal that the designed framework based on PCA and XGBoost models can effectively improve the orbit prediction accuracy in most cases. More importantly, the proposed model has excellent generalization capability for different satellites, which means that a model learned from one satellite can be used on another new satellite without learning from the historical data of the target satellite. Overall, it has been proved that the proposed ML model can be a supplement to dynamic models for improving the orbit prediction accuracy.
{"title":"Improvement of orbit prediction accuracy using extreme gradient boosting and principal component analysis","authors":"Min Zhai, Zongbo Huyan, Yuanyuan Hu, Yu Jiang, H. Li","doi":"10.1515/astro-2022-0030","DOIUrl":"https://doi.org/10.1515/astro-2022-0030","url":null,"abstract":"Abstract High-accuracy orbit prediction plays a crucial role in several aerospace applications, such as satellite navigation, orbital maneuver, space situational awareness, etc. The conventional methods of orbit prediction are usually based on dynamic models with clear mathematical expressions. However, coefficients of perturbation forces and relevant features of satellites are approximate values, which induces errors during the process of orbit prediction. In this study, a new orbit prediction model based on principal component analysis (PCA) and extreme gradient boosting (XGBoost) model is proposed to improve the accuracy of orbit prediction by learning from the historical data in a simulated environment. First, a series of experiments are conducted to determine the approximate numbers of features, which are used in the following machine learning (ML) process. Then, PCA and XGBoost models are used to find incremental corrections to orbit prediction with dynamic models. The results reveal that the designed framework based on PCA and XGBoost models can effectively improve the orbit prediction accuracy in most cases. More importantly, the proposed model has excellent generalization capability for different satellites, which means that a model learned from one satellite can be used on another new satellite without learning from the historical data of the target satellite. Overall, it has been proved that the proposed ML model can be a supplement to dynamic models for improving the orbit prediction accuracy.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"229 - 243"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47695622","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}
Abstract We have proposed a generalized King’s model for the observed density of stars in globular clusters (GC). Using two methods of minimizing the functional, composed in the form of the square of the difference between the theoretical and observed density values, we obtained the behavior of the degree of concentration for 26 GC. We have taken the observational data for these clusters from the work of Miocchi et al. (2013), which is a combination of ground-based and space-based observations. The minimized functional depends on three free parameters and one of them clearly characterizes the concentration of stars towards the center of the cluster. The two research methods used here give almost the same results with reasonably good accuracy. In contrast to the work of Nuritdinov et al. (2021), the χ2 method is used to determine the degree of concentration. In addition, we analyzed data from de Boer et al. (2019). However, these data do not contain information for the central regions of the clusters. The lack of these data does not allow finding the degree of concentration with the required accuracy.
{"title":"Determination of the degree of star concentration in globular clusters based on space observation data","authors":"S. Nuritdinov, Alexsey Rastorguev, I. Tadjibaev","doi":"10.1515/astro-2022-0001","DOIUrl":"https://doi.org/10.1515/astro-2022-0001","url":null,"abstract":"Abstract We have proposed a generalized King’s model for the observed density of stars in globular clusters (GC). Using two methods of minimizing the functional, composed in the form of the square of the difference between the theoretical and observed density values, we obtained the behavior of the degree of concentration for 26 GC. We have taken the observational data for these clusters from the work of Miocchi et al. (2013), which is a combination of ground-based and space-based observations. The minimized functional depends on three free parameters and one of them clearly characterizes the concentration of stars towards the center of the cluster. The two research methods used here give almost the same results with reasonably good accuracy. In contrast to the work of Nuritdinov et al. (2021), the χ2 method is used to determine the degree of concentration. In addition, we analyzed data from de Boer et al. (2019). However, these data do not contain information for the central regions of the clusters. The lack of these data does not allow finding the degree of concentration with the required accuracy.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"1 - 4"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44817913","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}
P. Pakhomova, L. Berdnikov, A. Kniazev, I. Katkov, O. Malkov
Abstract One of the important sources for independent determination of stellar masses is eclipsing binaries with components on the main sequence, and with observable spectral lines of both components. The parameters of such stars are used to construct the mass–luminosity relation for stars of high and intermediate masses. Among them, the type of long-period eclipsing binaries stands out, the parameters of which are currently not fully determined, which is associated with the difficulties caused by the need for long-term observations. In this article, we will review the currently available observational data for such objects and discuss the prospects for their use to determine stellar masses.
{"title":"Parameterization of long-period eclipsing binaries","authors":"P. Pakhomova, L. Berdnikov, A. Kniazev, I. Katkov, O. Malkov","doi":"10.1515/astro-2022-0013","DOIUrl":"https://doi.org/10.1515/astro-2022-0013","url":null,"abstract":"Abstract One of the important sources for independent determination of stellar masses is eclipsing binaries with components on the main sequence, and with observable spectral lines of both components. The parameters of such stars are used to construct the mass–luminosity relation for stars of high and intermediate masses. Among them, the type of long-period eclipsing binaries stands out, the parameters of which are currently not fully determined, which is associated with the difficulties caused by the need for long-term observations. In this article, we will review the currently available observational data for such objects and discuss the prospects for their use to determine stellar masses.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"106 - 109"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43825258","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}
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