Pub Date : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.004
Li jie, You Xiao-peng
Compared with normal pulsars, millisecond pulsars are a class of neutron stars with faster rotation speed, and the pulse signals emitted by them have extremely high stability. The stability of the polarization profile of pulsars is one of the important issues in the study of pulsar radiation mechanism and interstellar medium properties. The polarization profile stability of three millisecond pulsars PSR J10221001, PSR J1730-2304, and PSR J2129-5721 was studied using the observation data of the Parkes 64 m telescope in Australia. Analysis of the observations shows that the polarization profile changes slightly at different times. The reasons for the changes are analyzed and the possible explanations are proposed, including the effect of the interstellar scintillation and the instability of the intrinsic properties of the pulsars.
{"title":"Research on the Polarization Profile Stability of Millisecond Pulsars","authors":"Li jie, You Xiao-peng","doi":"10.1016/j.chinastron.2025.09.004","DOIUrl":"10.1016/j.chinastron.2025.09.004","url":null,"abstract":"<div><div>Compared with normal pulsars, millisecond pulsars are a class of neutron stars with faster rotation speed, and the pulse signals emitted by them have extremely high stability. The stability of the polarization profile of pulsars is one of the important issues in the study of pulsar radiation mechanism and interstellar medium properties. The polarization profile stability of three millisecond pulsars PSR J1022<span><math><mo>+</mo></math></span>1001, PSR J1730-2304, and PSR J2129-5721 was studied using the observation data of the Parkes 64 m telescope in Australia. Analysis of the observations shows that the polarization profile changes slightly at different times. The reasons for the changes are analyzed and the possible explanations are proposed, including the effect of the interstellar scintillation and the instability of the intrinsic properties of the pulsars.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 551-564"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098779","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.006
Li Shun , Ji Hang-xin , Zhang Hua-tao , Zhang Shu-ling , Hu Zhong-wen
The slitless spectroscopy assembly of the China Space Survey Telescope (CSST) will be installed in front of the main focal plane detectorof the sky survey module to conduct wide-field, wide-band slitless spectral observations. As an important dispersion element of the sky survey module, the slitless spectroscopy assembly is composed of 24 gratings and 12 filters. Spectral efficiency is one of the key technical parameters of the slitless spectroscopy assembly, and it needs to be tested during the development process. Due to the large envelope of the slitless spectroscopy assembly, commercial spectral efficiency measurement equipment cannot be used for testing. This paper addresses the issue of spectral efficiency testing for the slitless spectroscopy assembly. Firstly, the basic structure and measurement principles of the slitless spectroscopy assembly spectral efficiency test platform built in the laboratory are introduced. Then, the steps and results of the spectral efficiency measurement for the qualification model of the slitless spectroscopy assembly are given. Finally, the accuracy of the measurement results is analyzed and calculated using error synthesis theory. The measurement and calculation results show that the average spectral efficiency of the qualification model for the slitless spectroscopy assembly is respectively 51.9% in the GU band, 67.9% in the GV band, and 71.6% in the GI band (67.7% in the 900 nm–1000 nm band), meeting the technical requirements.
{"title":"Spectral Efficiency Testing and Error Analysis of Space Slitless Spectrograph","authors":"Li Shun , Ji Hang-xin , Zhang Hua-tao , Zhang Shu-ling , Hu Zhong-wen","doi":"10.1016/j.chinastron.2025.09.006","DOIUrl":"10.1016/j.chinastron.2025.09.006","url":null,"abstract":"<div><div>The slitless spectroscopy assembly of the China Space Survey Telescope (CSST) will be installed in front of the main focal plane detectorof the sky survey module to conduct wide-field, wide-band slitless spectral observations. As an important dispersion element of the sky survey module, the slitless spectroscopy assembly is composed of 24 gratings and 12 filters. Spectral efficiency is one of the key technical parameters of the slitless spectroscopy assembly, and it needs to be tested during the development process. Due to the large envelope of the slitless spectroscopy assembly, commercial spectral efficiency measurement equipment cannot be used for testing. This paper addresses the issue of spectral efficiency testing for the slitless spectroscopy assembly. Firstly, the basic structure and measurement principles of the slitless spectroscopy assembly spectral efficiency test platform built in the laboratory are introduced. Then, the steps and results of the spectral efficiency measurement for the qualification model of the slitless spectroscopy assembly are given. Finally, the accuracy of the measurement results is analyzed and calculated using error synthesis theory. The measurement and calculation results show that the average spectral efficiency of the qualification model for the slitless spectroscopy assembly is respectively 51.9% in the GU band, 67.9% in the GV band, and 71.6% in the GI band (67.7% in the 900 nm–1000 nm band), meeting the technical requirements.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 614-626"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098927","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.010
Zheng Hang , Zhu Qing-feng , Song Ye-zhi , Li Xu-zhi , Xu Xiao-hui , Qiu Jin-sheng , Zhao Jun-han
In view of the current situation of inconsistent conclusions among existing asteroid impact monitoring systems, the linear approximation method used in the change line impact monitoring system was studied, and the conclusion is achieved that the deviation of the orbit distribution relative to the theoretical orbit distribution obtained by this method gradually became significant as the orbit propagation time increased. The impact probability of 6 asteroid instances was calculated using the Monte Carlo method. Compared with the results of the existing Monte Carlo impact monitoring system, the maximum difference is 2.1 times the standard deviation. The impact samples of asteroid 2020 VV in October 2056 are analyzed in detail, and the distribution of impact samples with time and space is depicted, and the conclusions are consistent with those of existing impact monitoring systems. As for the comparison between the different impact monitoring systems, it is concluded that the Monte Carlo impact monitoring system and the change line impact monitoring system currently have their own advantages and disadvantages: the former does not introduce the error caused by the linear approximation method, but the computational cost is high. The linear approximation method used in the latter will bring errors, but it can find some virtual impact sources with low impact probability that may be missed by the former, and the computational cost is relatively low.
{"title":"Research on the Analysis Method of Asteroid Impact Probability","authors":"Zheng Hang , Zhu Qing-feng , Song Ye-zhi , Li Xu-zhi , Xu Xiao-hui , Qiu Jin-sheng , Zhao Jun-han","doi":"10.1016/j.chinastron.2025.09.010","DOIUrl":"10.1016/j.chinastron.2025.09.010","url":null,"abstract":"<div><div>In view of the current situation of inconsistent conclusions among existing asteroid impact monitoring systems, the linear approximation method used in the change line impact monitoring system was studied, and the conclusion is achieved that the deviation of the orbit distribution relative to the theoretical orbit distribution obtained by this method gradually became significant as the orbit propagation time increased. The impact probability of 6 asteroid instances was calculated using the Monte Carlo method. Compared with the results of the existing Monte Carlo impact monitoring system, the maximum difference is 2.1 times the standard deviation. The impact samples of asteroid 2020 VV in October 2056 are analyzed in detail, and the distribution of impact samples with time and space is depicted, and the conclusions are consistent with those of existing impact monitoring systems. As for the comparison between the different impact monitoring systems, it is concluded that the Monte Carlo impact monitoring system and the change line impact monitoring system currently have their own advantages and disadvantages: the former does not introduce the error caused by the linear approximation method, but the computational cost is high. The linear approximation method used in the latter will bring errors, but it can find some virtual impact sources with low impact probability that may be missed by the former, and the computational cost is relatively low.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 565-578"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098930","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.007
Pi Chun-mei , Yang Shu-hua
The effects of non-Newtonian gravity on the properties of color-flavor-locked strange quark stars are studied using the standard MIT bag model. It is shown that the maximum mass of color-flavor-locked strange quark stars increases not only with the increasing of the value of color-superconducting energy gap, but also with the increasing of the non-Newtonian gravity parameter. Moreover, color-superconducting energy gap and non-Newtonian gravity parameter are constrained by the mass of the second component of the GW190814 event ( 2.6 ). It turns out that 2.6 ( is the maximum mass of the stars) can be satisfied only if 94.5 MeV ( is the color-superconducting energy gap) without the consideration of non-Newtonian gravity effects. However, if non-Newtonian gravity effects are included, smaller values of could satisfy 2.6 . Since small color-superconducting energy gap is favored by the surface temperature observation of the central compact object in Hess J1731-347 supernova remnant, the inclusion of non-Newtonian gravity effects is helpful in the explanation of the observed large mass of the second component of the GW190814 event.
{"title":"Non-Newtonian Gravity Effects of Color-Flavor-Locked Strange Stars and the Second Component of the GW190814 Event","authors":"Pi Chun-mei , Yang Shu-hua","doi":"10.1016/j.chinastron.2025.09.007","DOIUrl":"10.1016/j.chinastron.2025.09.007","url":null,"abstract":"<div><div>The effects of non-Newtonian gravity on the properties of color-flavor-locked strange quark stars are studied using the standard MIT bag model. It is shown that the maximum mass of color-flavor-locked strange quark stars increases not only with the increasing of the value of color-superconducting energy gap, but also with the increasing of the non-Newtonian gravity parameter. Moreover, color-superconducting energy gap and non-Newtonian gravity parameter are constrained by the mass of the second component of the GW190814 event (<span><math><mrow><mi>M</mi><mo>=</mo></mrow></math></span> 2.6 <span><math><msub><mi>M</mi><mo>⊙</mo></msub></math></span>). It turns out that <span><math><mrow><msub><mi>M</mi><mi>max</mi></msub><mo>></mo></mrow></math></span> 2.6 <span><math><msub><mi>M</mi><mo>⊙</mo></msub></math></span> (<span><math><msub><mi>M</mi><mi>max</mi></msub></math></span> is the maximum mass of the stars) can be satisfied only if <span><math><mrow><mstyle><mi>Δ</mi></mstyle><mo>></mo></mrow></math></span> 94.5 MeV (<span><math><mstyle><mi>Δ</mi></mstyle></math></span> is the color-superconducting energy gap) without the consideration of non-Newtonian gravity effects. However, if non-Newtonian gravity effects are included, smaller values of <span><math><mstyle><mi>Δ</mi></mstyle></math></span> could satisfy <span><math><mrow><msub><mi>M</mi><mi>max</mi></msub><mo>></mo></mrow></math></span> 2.6 <span><math><msub><mi>M</mi><mo>⊙</mo></msub></math></span>. Since small color-superconducting energy gap is favored by the surface temperature observation of the central compact object in Hess J1731-347 supernova remnant, the inclusion of non-Newtonian gravity effects is helpful in the explanation of the observed large mass of the second component of the GW190814 event.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 526-536"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098932","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.009
Wang Xiang , Song Hui-jie , Guo Dong , Gao Zhe , Wang Wei-xiong , Wu Wen-jun , Dong Shao-wu
In order to fully utilize different types of time transfer links, it is necessary to realize the fusion application of time transfer link data under different sampling rates. This article proposes a data fusion method based on multi-resolution analysis. Firstly, we perform wavelet decomposition on the original data to achieve a unified resolution and initially eliminate high-frequency noise. Subsequently, Kalman filtering is employed across various resolutions. Ultimately, the Mallat fast reconstruction algorithm is utilized to derive the fusion result. The method is used to process time transfer data between the National Time Service Center (NTSC) of the Chinese Academy of Sciences and the Physikalisch-Technische Bundesanstalt (PTB) of Germany. The results show that the fusion algorithm can handle data problems caused by link anomalies or interruptions. Since the actual measurement results of the GPS (Global Positioning System) PPP (Precise Point Positioning solutions) link perform better than those of the TWSTFT (Two-Way Satellite Time and Frequency Transfer) link overall, the GPS PPP link measurement results are used to evaluate the gain of the fusion algorithm. Using Rapid Realization of Coordinated Universal Time (UTCr) as the reference, the accuracy gain of the data fusion result is about 1%, and the daily frequency stability gain is better than 20%. At the same time, the fusion algorithm can suppress the periodic noise of the TWSTFT link, effectively improving the stability and robustness of the link.
为了充分利用不同类型的时间传递链路，需要实现不同采样率下时间传递链路数据的融合应用。提出了一种基于多分辨率分析的数据融合方法。首先对原始数据进行小波分解，得到统一分辨率，初步消除高频噪声。随后，在各种分辨率下采用卡尔曼滤波。最后，利用Mallat快速重构算法推导融合结果。该方法用于处理中国科学院国家时间服务中心（NTSC）与德国物理技术Bundesanstalt （PTB）之间的时间传输数据。结果表明，该融合算法可以处理链路异常或中断引起的数据问题。由于GPS (Global Positioning System) PPP （Precise Point Positioning solutions）链路的实际测量结果总体上优于TWSTFT （two Satellite Time and Frequency Transfer）链路，因此使用GPS PPP链路的测量结果来评估融合算法的增益。以快速实现协调世界时（UTCr）为基准，数据融合结果的精度增益约为1%，日频率稳定增益优于20%。同时，融合算法可以抑制TWSTFT链路的周期性噪声，有效提高链路的稳定性和鲁棒性。
{"title":"Research on Data Fusion Method of Time Transfer Link under Unequal-interval Measurement Conditions","authors":"Wang Xiang , Song Hui-jie , Guo Dong , Gao Zhe , Wang Wei-xiong , Wu Wen-jun , Dong Shao-wu","doi":"10.1016/j.chinastron.2025.09.009","DOIUrl":"10.1016/j.chinastron.2025.09.009","url":null,"abstract":"<div><div>In order to fully utilize different types of time transfer links, it is necessary to realize the fusion application of time transfer link data under different sampling rates. This article proposes a data fusion method based on multi-resolution analysis. Firstly, we perform wavelet decomposition on the original data to achieve a unified resolution and initially eliminate high-frequency noise. Subsequently, Kalman filtering is employed across various resolutions. Ultimately, the Mallat fast reconstruction algorithm is utilized to derive the fusion result. The method is used to process time transfer data between the National Time Service Center (NTSC) of the Chinese Academy of Sciences and the Physikalisch-Technische Bundesanstalt (PTB) of Germany. The results show that the fusion algorithm can handle data problems caused by link anomalies or interruptions. Since the actual measurement results of the GPS (Global Positioning System) PPP (Precise Point Positioning solutions) link perform better than those of the TWSTFT (Two-Way Satellite Time and Frequency Transfer) link overall, the GPS PPP link measurement results are used to evaluate the gain of the fusion algorithm. Using Rapid Realization of Coordinated Universal Time (UTCr) as the reference, the accuracy gain of the data fusion result is about 1%, and the daily frequency stability gain is better than 20%. At the same time, the fusion algorithm can suppress the periodic noise of the TWSTFT link, effectively improving the stability and robustness of the link.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 579-594"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098929","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.005
Liu Qiang , Liu Yu , Song Teng-fei , Ren An-bing , Zhao Ming-yu , Zhang Xue-fei , Li Xiao-bo , Zhu Feng-rong , Sha Fei-yang , Oloketuyi Jacob Oladeji , Wang Xin-jian , Duan Xiao-mei , Luo Qi-wang
The sky brightness is an important parameter to evaluate the excellence of a coronal observatory, which directly determines whether the coronagraph can measure and monitor the coronal activity for a long time. The Sky Brightness Moniter (SBM) is a precision instrument for accurately measuring important atmospheric parameters such as the sky brightness, water vapor content, and atmospheric extinction. It is also an universal instrument for coronagraph site selection and an important equipment for solar site selection in western China. Before conducting statistical analysis on the accumulated data from Namco, this paper first performs an in-depth analysis using representative data from Namco and Lijiang. The aim is to preliminarily study and understand the characteristics of the sky brightness at the site based on the profiles of the representative data. Firstly, by considering the actual climatic characteristics and the normalized sky brightness, the paper gradually explains the different variations of the sky brightness throughout the day. Secondly, we establish an effective calculation method to measure and reveal the evolution characteristics of the sky brightness. The results show: 1) The sky brightness (green line, 530 nm) at the Lijiang station with an altitude of 3200 meters and the Namco site with an altitude of 4700 meters are both relatively good. The minimum values can reach the order of , ensuring the feasibility of regular corona observations. 2) The sky brightness at the Namco site and the Lijiang station evolves differently over time. The Lijiang station is not suitable for all-day observations, with morning conditions being far superior to those in the afternoon. In contrast, the Namco site has a longer observation time (from 9:00 AM to 4:00 PM), and its cooperation with the observation equipment of other stations can significantly improve the efficiency of space weather ground monitoring. The analysis results not only provides a sample analysis for subsequent statistics on the sky brightness at Namco but also demonstrates the expected characteristics of the sky brightness at Namco.
{"title":"The Variations in the Sky Brightness of Lijiang and Namco throughout the Day","authors":"Liu Qiang , Liu Yu , Song Teng-fei , Ren An-bing , Zhao Ming-yu , Zhang Xue-fei , Li Xiao-bo , Zhu Feng-rong , Sha Fei-yang , Oloketuyi Jacob Oladeji , Wang Xin-jian , Duan Xiao-mei , Luo Qi-wang","doi":"10.1016/j.chinastron.2025.09.005","DOIUrl":"10.1016/j.chinastron.2025.09.005","url":null,"abstract":"<div><div>The sky brightness is an important parameter to evaluate the excellence of a coronal observatory, which directly determines whether the coronagraph can measure and monitor the coronal activity for a long time. The Sky Brightness Moniter (SBM) is a precision instrument for accurately measuring important atmospheric parameters such as the sky brightness, water vapor content, and atmospheric extinction. It is also an universal instrument for coronagraph site selection and an important equipment for solar site selection in western China. Before conducting statistical analysis on the accumulated data from Namco, this paper first performs an in-depth analysis using representative data from Namco and Lijiang. The aim is to preliminarily study and understand the characteristics of the sky brightness at the site based on the profiles of the representative data. Firstly, by considering the actual climatic characteristics and the normalized sky brightness, the paper gradually explains the different variations of the sky brightness throughout the day. Secondly, we establish an effective calculation method to measure and reveal the evolution characteristics of the sky brightness. The results show: 1) The sky brightness (green line, 530 nm) at the Lijiang station with an altitude of 3200 meters and the Namco site with an altitude of 4700 meters are both relatively good. The minimum values can reach the order of <span><math><mrow><mn>10</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span>, ensuring the feasibility of regular corona observations. 2) The sky brightness at the Namco site and the Lijiang station evolves differently over time. The Lijiang station is not suitable for all-day observations, with morning conditions being far superior to those in the afternoon. In contrast, the Namco site has a longer observation time (from 9:00 AM to 4:00 PM), and its cooperation with the observation equipment of other stations can significantly improve the efficiency of space weather ground monitoring. The analysis results not only provides a sample analysis for subsequent statistics on the sky brightness at Namco but also demonstrates the expected characteristics of the sky brightness at Namco.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 627-644"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098782","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.001
Zhuang Yu-yi , Ping Yi-ding , Zhao Hai-bin
It has become a consensus that near-Earth asteroids (NEAs) threaten global security, thus their detection is of great significance. The Multi-Application Survey Telescope Array (MASTA), with its wide field of view, multiple telescopes, and large aperture, is particularly well suited for NEA detection. Its addition can significantly enhance China's capability in this regard. To leverage MASTA's advantages in NEA detection, we propose a survey strategy for near-Earth objects and present a scheduling model based on the integer linear programming method. To evaluate the model's effectiveness and MASTA's performance in NEA detection under this framework, we generate a synthetic NEA dataset by augmenting the known population and then conduct a one-year survey simulation. The simulation results indicate that the scheduling model can effectively meet the requirements of MASTA's survey for NEAs and optimize the allocation of observational resources while considering other scientific goals. We find that MASTA can achieve a one-year detection completeness of 1.29% for the synthetic NEA population.
{"title":"A Near-Earth Object Survey Planning and Scheduling Model for Multi-Application Survey Telescope Array","authors":"Zhuang Yu-yi , Ping Yi-ding , Zhao Hai-bin","doi":"10.1016/j.chinastron.2025.09.001","DOIUrl":"10.1016/j.chinastron.2025.09.001","url":null,"abstract":"<div><div>It has become a consensus that near-Earth asteroids (NEAs) threaten global security, thus their detection is of great significance. The Multi-Application Survey Telescope Array (MASTA), with its wide field of view, multiple telescopes, and large aperture, is particularly well suited for NEA detection. Its addition can significantly enhance China's capability in this regard. To leverage MASTA's advantages in NEA detection, we propose a survey strategy for near-Earth objects and present a scheduling model based on the integer linear programming method. To evaluate the model's effectiveness and MASTA's performance in NEA detection under this framework, we generate a synthetic NEA dataset by augmenting the known population and then conduct a one-year survey simulation. The simulation results indicate that the scheduling model can effectively meet the requirements of MASTA's survey for NEAs and optimize the allocation of observational resources while considering other scientific goals. We find that MASTA can achieve a one-year detection completeness of 1.29% for the synthetic NEA population.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 595-613"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098928","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.008
Tong Yi-lu , Dai Yu
The launch of JWST has brought astronomers a wealth of observational data on distant galaxies, which is particularly crucial in the study of galaxy interaction and galaxy mergers. JWST's infrared observation capabilities offer a unique perspective to astronomers, revealing the gas dynamics and star formation activities within galaxies. Merger events are prevalent throughout the universe, and research based on JWST observation data further confirms the significant impact of mergers on galaxy evolution. Significant progress has been made in the study of galaxies associated with JWST, including both statistical studies and individual case studies, as well as the integration of theoretical simulations with actual observations. JWST also provides a unique perspective for observing emission-line galaxies, and it is widely applied in studies across various redshifts, especially in high-redshift galaxy research. JWST plays a vital role in merger galaxy research, with its infrared observation capabilities providing unprecedented advantages in exploring galaxy structure and composition. Its high resolution and sensitivity make it an ideal tool for studying galaxy mergers, offering astronomers new opportunities and posing challenges in understanding galaxy evolution at a deeper level.
{"title":"Recent Research Progress on Galaxy Pairs and Mergers with JWST Observations","authors":"Tong Yi-lu , Dai Yu","doi":"10.1016/j.chinastron.2025.09.008","DOIUrl":"10.1016/j.chinastron.2025.09.008","url":null,"abstract":"<div><div>The launch of JWST has brought astronomers a wealth of observational data on distant galaxies, which is particularly crucial in the study of galaxy interaction and galaxy mergers. JWST's infrared observation capabilities offer a unique perspective to astronomers, revealing the gas dynamics and star formation activities within galaxies. Merger events are prevalent throughout the universe, and research based on JWST observation data further confirms the significant impact of mergers on galaxy evolution. Significant progress has been made in the study of galaxies associated with JWST, including both statistical studies and individual case studies, as well as the integration of theoretical simulations with actual observations. JWST also provides a unique perspective for observing emission-line galaxies, and it is widely applied in studies across various redshifts, especially in high-redshift galaxy research. JWST plays a vital role in merger galaxy research, with its infrared observation capabilities providing unprecedented advantages in exploring galaxy structure and composition. Its high resolution and sensitivity make it an ideal tool for studying galaxy mergers, offering astronomers new opportunities and posing challenges in understanding galaxy evolution at a deeper level.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 493-525"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098933","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.002
Dong Shu-yu, Zhang Jin-qu
The spiral arm information contained in spiral galaxy images, especially the number of spiral arms, is of great value for studying the structural evolution and dynamics of galaxies. Against the backdrop of explosive growth in galaxy observation data, how to quickly identify the number of spiral arms has become an important issue in the study of spiral galaxies. The research is based on the Galaxy Zoo DECaLS (Dark Energy Camera Legacy Survey) dataset and studies the ResNet (Residual Networks) model's method of identifying the number of spiral arms from spiral galaxy images. The experimental results show that the accuracy of the ResNet32 model is 83%, which is the best compared to network models such as ViT (Vision Transformer), EfficientNet, and DenseNet. In terms of recognition of different numbers of spiral arms, there is a strong relationship between recognition accuracy and the number of training samples. There are 6800 images with 2 spiral arms, with an F1-Score value of 0.9, while there are only 237 images with 4 spiral arms, with the lowest F1-Score value. The experiment further analyzed the recognition effect of fused traditional galaxy image features and found that the role of fused traditional galaxy image features in improving the recognition of spiral arms is limited.
{"title":"Analysis of the Recognition Effect on the Number of Spiral Arms in Spiral Galaxy Images Using ResNet","authors":"Dong Shu-yu, Zhang Jin-qu","doi":"10.1016/j.chinastron.2025.09.002","DOIUrl":"10.1016/j.chinastron.2025.09.002","url":null,"abstract":"<div><div>The spiral arm information contained in spiral galaxy images, especially the number of spiral arms, is of great value for studying the structural evolution and dynamics of galaxies. Against the backdrop of explosive growth in galaxy observation data, how to quickly identify the number of spiral arms has become an important issue in the study of spiral galaxies. The research is based on the Galaxy Zoo DECaLS (Dark Energy Camera Legacy Survey) dataset and studies the ResNet (Residual Networks) model's method of identifying the number of spiral arms from spiral galaxy images. The experimental results show that the accuracy of the ResNet32 model is 83%, which is the best compared to network models such as ViT (Vision Transformer), EfficientNet, and DenseNet. In terms of recognition of different numbers of spiral arms, there is a strong relationship between recognition accuracy and the number of training samples. There are 6800 images with 2 spiral arms, with an F1-Score value of 0.9, while there are only 237 images with 4 spiral arms, with the lowest F1-Score value. The experiment further analyzed the recognition effect of fused traditional galaxy image features and found that the role of fused traditional galaxy image features in improving the recognition of spiral arms is limited.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 537-550"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098778","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 : 2025-07-01DOI: 10.1016/j.chinastron.2025.09.003
Liu Gong-lin , Ning Hao , Ni Su-lan , Li Chuan-yang , Zhang Zi-long , Li Yao-kun , Chen Yao
Electron Cyclotron Maser Emission (ECME) driven by electrons with loss-cone distribution is the main mechanism for explaining solar radio spikes. However, in strongly magnetized plasmas, the losscone-driven ECME mainly generates fundamental X mode emissions, which can be efficiently absorbed when escaping through the second-harmonic layer in the solar corona. To solve the "escaping difficulty", recent studies suggested a new mechanism of harmonic maser emission (X2) involving nonlinear wave coupling process of Z-mode and fundamental X-mode (X1) waves (Z+ZX2, Z+X1X2). It is necessary to verify the nonlinear wave coalescence process with theoretical analyses and numerical simulations. Here, the possibility of a nonlinear wave coupling process is examined via solving the matching conditions for three-wave resonant interaction based on the dispersion relation of cold plasma in magneto-ionic theory. The matching conditions for the Z and/or X1 waves were found to be satisfied over a wide range of parameters, leading to the production of X2 emissions that propagate perpendicularly and obliquely relative to the direction of the background magnetic field. Based on the solutions obtained in the matching condition analysis, we selected four sets of solutions of Z+Z and Z+X1 to perform particle-in-cell simulations using wave pumping method, to verify the nonlinear process of wave coalescence generating second harmonic X-mode emissions. With X1 and/or Z modes correctly pumped in the simulation domain, efficient generation of X2 emissions was observed, with saturation achieved within 400 . The conversion rate of energies of X2 emissions to Z mode waves varies from 2% to 8%. The study presents strong evidence to support the new mechanism of harmonic maser emission, which can be widely applied to explain the solar and space radio emissions.
{"title":"Simulation on the Mechanism of Harmonic Maser Emission through the Wave Coalescence Process","authors":"Liu Gong-lin , Ning Hao , Ni Su-lan , Li Chuan-yang , Zhang Zi-long , Li Yao-kun , Chen Yao","doi":"10.1016/j.chinastron.2025.09.003","DOIUrl":"10.1016/j.chinastron.2025.09.003","url":null,"abstract":"<div><div>Electron Cyclotron Maser Emission (ECME) driven by electrons with loss-cone distribution is the main mechanism for explaining solar radio spikes. However, in strongly magnetized plasmas, the losscone-driven ECME mainly generates fundamental X mode emissions, which can be efficiently absorbed when escaping through the second-harmonic layer in the solar corona. To solve the \"escaping difficulty\", recent studies suggested a new mechanism of harmonic maser emission (X2) involving nonlinear wave coupling process of Z-mode and fundamental X-mode (X1) waves (Z+Z<span><math><mo>→</mo></math></span>X2, Z+X1<span><math><mo>→</mo></math></span>X2). It is necessary to verify the nonlinear wave coalescence process with theoretical analyses and numerical simulations. Here, the possibility of a nonlinear wave coupling process is examined via solving the matching conditions for three-wave resonant interaction based on the dispersion relation of cold plasma in magneto-ionic theory. The matching conditions for the Z and/or X1 waves were found to be satisfied over a wide range of parameters, leading to the production of X2 emissions that propagate perpendicularly and obliquely relative to the direction of the background magnetic field. Based on the solutions obtained in the matching condition analysis, we selected four sets of solutions of Z+Z and Z+X1 to perform particle-in-cell simulations using wave pumping method, to verify the nonlinear process of wave coalescence generating second harmonic X-mode emissions. With X1 and/or Z modes correctly pumped in the simulation domain, efficient generation of X2 emissions was observed, with saturation achieved within 400 <span><math><msubsup><mstyle><mi>Ω</mi></mstyle><mrow><mtext>ce</mtext></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math></span>. The conversion rate of energies of X2 emissions to Z mode waves varies from 2% to 8%. The study presents strong evidence to support the new mechanism of harmonic maser emission, which can be widely applied to explain the solar and space radio emissions.</div></div>","PeriodicalId":35730,"journal":{"name":"Chinese Astronomy and Astrophysics","volume":"49 3","pages":"Pages 479-492"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098931","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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