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Quality Control of YFOSC Data I. The On-site Quick Analysis System

Research in Astronomy and Astrophysics 2023年第3期23卷 119-127页

作者： Jian-Guo Wang Jin-Ming Bai Ying-He Zhao Xiao-Bo Dong Kai-Xing Lu Chuan-Jun Wang Ju-Jia Zhang Yu-Xin Xin Yunnan Observatories Chinese Academy of SciencesKunming 650011China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan ObservatoriesKunming 65001lChina

The Lijiang 2.4 m Telescope(LJT)is one of the most important telescopes for general astronomical observations in *** Faint Object Spectrograph and Camera(YFOSC)is a widely used instrument mounted on the LJT,which occupies for~80%of the observing time of the LJT,and thus instrument health and data quality of the YFOSC are very important for both the telescope maintenance team and users of the *** we develop an automated data analysis system for the quality control(QC)of YFOSC *** system is also a new function of the observing support of the *** on the system,YFOSC data can be reduced quickly as they are acquired and QC parameters are *** can assess the quality of their data and make a possible revision of their observing plan in *** parameters can also be used to check the health of the YFOSC,which is helpful for the telescope maintenance team to find potential *** of these aim at improving the productivity of the LJT.

关键词： Quick Observer YFOSC

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Simulating the Escaping Atmosphere of GJ 436 b with Two-fluid Magnetohydrodynamic Models

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Research in Astronomy and Astrophysics 2024年第6期24卷 273-286页

作者： Lei Xing Jianheng Guo Chuyuan Yang Dongdong Yan Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China International Centre of Supernovae Yunnan Key LaboratoryKunming 650216China

Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar *** models predict that magnetic fields may exert significant influences on the atmospheres of hot ***,the escaping atmospheres are not entirely ionized,and magnetic fields only directly affect the escape of ionized components within *** the chemical reactions between ionized components and neutral atoms,as well as collision processes,magnetic fields indirectly impact the escape of neutral atoms,thereby influencing the detection signals of planetary atmospheres in transmission *** order to simulate this process,we developed a magnetohydrodynamic multi-fluid model based on MHD code *** an initial exploration,we investigated the impact of magnetic fields on the decoupling of H^(+)and H in the escaping atmosphere of the hot Neptune *** to the strong resonant interactions between H and H^(+),the coupling between them is tight even if the magnetic field is *** course,alternatively,our work also suggests that merging H and H^(+)into a single flow can be a reasonable assumption in MHD simulations of escaping ***,our simulation results indicate that under the influence of magnetic fields,there are noticeable regional differences in the decoupling of H^(+)and *** the increase of magnetic field strength,the degree of decoupling also *** heavier particles such as O,the decoupling between O and H^(+)is more *** findings provide important insights for future studies on the decoupling processes of heavy atoms in the escaping atmospheres of hot Jupiters and hot Neptunes under the influence of magnetic fields.

关键词： magnetohydrodynamics(MHD) planets and satellites:atmospheres hydrodynamics

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Resolution Enhancement of SOHO/MDI Magnetograms

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Research in Astronomy and Astrophysics 2024年第6期24卷 358-367页

作者： Ying Qin Kai-Fan Ji Hui Liu Xiao-Guang Yu Yunnan Observatories Chinese Academy of SciencesKunming 650011China University of Chinese Academy of Sciences Beijing 100049China Yunnan Key Laboratory of Solar Physics and Space Science Kunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

Research on the solar magnetic field and its effects on solar dynamo mechanisms and space weather events has benefited from the continual improvements in instrument resolution and measurement *** augmentation and assimilation of historical observational data timelines also play a significant role in understanding the patterns of solar magnetic field *** the realm of astronomical data processing,super-resolution(SR)reconstruction refers to the process of using a substantial corpus of training data to learn the nonlinear mapping between low-resolution(LR)and high-resolution(HR)images,thereby achieving higherresolution astronomical *** paper is an application study in high-dimensional nonlinear *** learning models were employed to perform SR modeling on SOHO/MDI magnetograms and SDO/HMI magnetograms,thus reliably achieving resolution enhancement of full-disk SOHO/MDI magnetograms and enhancing the image resolution to obtain more detailed *** this study,a data set comprising 9717pairs of data from 2010 April to 2011 February was used as the training set,1332 pairs from 2011 March were used as the validation set and 1034 pairs from 2011 April were used as the test *** data preprocessing,we randomly cropped 128×128 sub-images as the LR cases from the full-disk MDI magnetograms,and the corresponding 512×512 sub-images as HR ones from the HMI full-disk magnetograms for model *** tests conducted have shown that the study successfully produced reliable 4×SR reconstruction of full-disk MDI *** MESR model's results(0.911)were highly correlated with the target HMI magnetographs as indicated by the correlation coefficient ***,the method achieved the best PSNR,SSIM,MAE and RMSE values,indicating that the MESR model can effectively reconstruct magnetograms.

关键词： magnetic fields techniques:image processing virtual observatory tools Sun:magnetic fields

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Classification of Galaxy Morphology Based on FPN-ViT Model

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Chinese Astronomy and Astrophysics 2024年第4期48卷 683-704页

作者： Jie, Cao Ting-ting, Xu Yu-he, Deng Guang-ping, Li Xian-jun, Gao Ming-cun, Yang Zhi-jing, Liu Wei-hong, Zhou School of Mathematics and Computer Science Yunnan Minzu University Kunming 650504 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China

With the development of artificial intelligence technology, the research of galaxy morphology classification using deep learning methods has made great progress, but there are still shortcomings in classification accuracy, automation, and spatial characteristics representation of galaxies. The Vision Transformer model (ViT) has good robustness in galaxy morphology classification, but has limitations in handling multi-scale images. In this paper, we propose to introduce the Feature Pyramid Networks (FPN) into the ViT model to classify galaxies. The results show that the average accuracy, precision, recall, and F1-score of the FPN-ViT model are above 95%, and the indexes are improved compared with the traditional ViT model. Meanwhile, we add different levels of Gaussian noise and pretzel noise to the original galaxy images to verify that the FPN-ViT model can obtain better classification performance for low signal -to-noise ratio data. In addition, to evaluate the model comprehensively, the t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm is used to visualize and analyze the classification results, which can show the effect of FPN-ViT model on galaxy morphology classification more directly. The application of FPN network to the classification of galaxy morphology by ViT model is a new attempt, which is of great importance for the subsequent research. © 2024

关键词： methods: data analysis—techniques: image processing—galaxy: general

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On the Surface Helium Abundance of B-type Hot Subdwarf Stars from the WD+MS Channel of Type Ia Supernovae

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Research in Astronomy and Astrophysics 2024年第5期24卷 21-27页

作者： Rui-Jie Ji Xiang-Cun Meng Zheng-Wei Liu Yunnan Observatories Chinese Academy of SciencesKunming 650216Kunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China International Centre of Supernovae(ICESUN) Yunnan Key LaboratoryKunming 650216China

The origin of intermediate helium (He)-rich hot subdwarfs is still *** studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel may contribute to the intermediate He-rich hot ***,previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia,leading to the aspect that they could not explain the observed surface He abundance of intermediate He-rich hot *** this work,by taking the atomic diffusion and stellar wind into account,we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code MESA until they evolve into hot *** find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of-1■log(N_(He) N_(H))■0,which are consistent with those observed in intermediate He-rich hot *** seems to further support the notion that it is possible for surviving companions of SNe Ia in the WD+MS channel to form some intermediate He-rich hot subdwarfs.

关键词： (stars:)subdwarfs-atomic processes-diffusion

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Period Investigation on Two W UMa Binaries HH UMa and V1175 Her

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Research in Astronomy and Astrophysics 2023年第4期23卷 184-193页

作者： Linfeng Chang Liying Zhu Fangbin Meng Yunnan Observatories Chinese Academy of Sciences(CAS)Kunming 650216China University of Chinese Academy of Sciences Beijing 101408China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

HH UMa and V1175 Her are two W UMa contact binary systems whose periods were reported as undergoing secular *** this paper,we improved their period analyses with a more extensive database of eclipse timings,finding that both periods show cyclic *** cyclic variation could be attributed to a Light Travel Time Effect induced by a third *** circular orbit and eccentric orbit cases were *** HH UMa,the cyclic variation with a period of around 20 yr has been detected,which may be caused by a third body with the mass larger than 0.23 M_(⊙).However,no parabolic variation was detected in its O−C curve,implying the balance of the mass transfer between the two components and the angular momentum loss from the binary *** to V1175 Her,a long-term period increase superposed on a periodic oscillation was *** period increase with a rate of about dP/dt=2×10^(-7)day yr^(−1)indicates the mass transfer from the less massive component to its *** cyclic variation of about 7.5 yr could be caused by a hierarchical third body with a minimal mass exceeding 0.46M_(⊙)orbiting around the central *** mass is larger than that of the less massive component of the binary,which means that the secondary component was not replaced by the third body during early stellar interactions,implying that it keeps original dynamical *** removing angular momentum from the central binary system,the tertiary component has played a significant role in the formation of contact binaries.

关键词： (stars:)binaries eclipsing-(stars:)binaries(including multiple) close-stars late-type

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Stellar Populations of AGN-host Dwarf Galaxies Selected with Different Methods

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Research in Astronomy and Astrophysics 2024年第6期24卷 52-67页

作者： Xiejin Li 赵应和 Jinming Bai Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Radio Astronomy and Technology Chinese Academy of SciencesBeijing 100101China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China

In this paper we investigate the stellar populations and star formation histories of 235 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,radio,X-ray,mid-IR and variability),utilizing the synthesis code STARLIGHT and spectra from the Sloan Digital Sky Survey Data Release *** results show that the variability sample is the oldest,while the mid-IR sample is the youngest,for which the luminosity at 4020?is dominated(>50%)by the young population(t<10~8yr).The light-weighted mean stellar age of the whole sample is in general about 0.7 dex younger than the optical sample studied in Cai et *** compare the population results between fitting models with and without a power-law(PL)component and find that the neglect of a PL component would lead to an under-and over-estimation by 0.2 and0.1 dex for the light-and mass-weighted mean stellar age,respectively,for our sample of dwarf galaxies,which has a mean fractional contribution of~16%from the *** addition,we obtain further evidence for a possible suppression of star formation in the host galaxy by the central *** also find that there exists an anticorrelation between the extinction-corrected[O III]luminosity and light-weighted mean stellar age,confirming our previous finding that there is a physical connection between AGN and star-forming activities in AGN-host dwarfs.

关键词： galaxies:dwarf galaxies:active galaxies:stellar content

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Photometric Analysis for Asteroid(81)Terpsichore using Convex Inversion and Phase Function Fitting Methods

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Research in Astronomy and Astrophysics 2024年第6期24卷 201-208页

作者： Ao Wang Xiaobin Wang Xiaoyun Xu Longhua Qin Quangui Gao Huaizhen Li Yong Xiao Hairu Zhao Department of Physics Yuxi Normal UniversityYuxi 653100China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China

The shapes and rotation states(periods and pole orientations)of main-belt asteroids are important for understanding their formation and *** order to obtain sufficient photometric data covering different apparitions for asteroid(81)Terpsichore,ground-based photometric observations in 2020 and 2021 were carried *** combining published and newly obtained photometric data,we calculated the shape and spin parameters for(81)Terpsichore using the convex inversion *** this method,we have derived a best fitted pole orientation—(22.2±_(3.1)^(3.3°),17.5±_(5.5)^(10.8°))with a spin period of 10.94±_(0.01)^(0.01)*** on the derived convex shape of(81)Terpsichore,we have fitted the H,G+1,G_(2)phase function using the calibrated TESS data and Gaia data after accounting for the lightcurve amplitude *** a result,we have derived its absolute magnitude H=8.68±_(0.19)^(0.22)mag with corresponding phase function parameters G_(1)=0.82±_(0.10)^(0.09)and G_(2)=0.02±_(0.02)^(0.03).

关键词： asteroids:general minor planets asteroids:individual(Terpsichore) techniques:photometric

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The Impact of Tidal Migration of Hot Jupiters on the Rotation of Sun-like Main-sequence Stars

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Research in Astronomy and Astrophysics 2023年第9期23卷 148-161页

作者： Shuai-Shuai Guo Yunnan Observatories Chinese Academy of SciencesKunming 650011China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects CASKunming 650011China

The tidal interactions of planets affect the stellar evolutionary status and the constraint of their physical parameters by *** this work,we incorporate the tidal interaction and magnetic braking of the stellar wind into MESA and calculate a large grid of 25,000 models,covering planets with masses of 0.1–13.0MJ with different orbital distances that orbit late-type stars of different *** also explore the effect of different stellar initial rotations on the tidal *** results show that in the case of tidal inward migration,the stellar rotation periods are always lower than that of the star without planet before the planet is engulfed and the difference in the rotation period of its host star always increases with *** the planet is engulfed,the stellar rotation periods are still lower than that of star without planet,but the difference of periods can be quickly eliminated if the star has a thick convective envelope(smaller mass and larger metallicity),regardless of the mass of the planet and the initial rotation period of the *** the case of stars with thinner convective envelopes(larger mass and smaller metallicity),the stars will be spun up and remain the faster rotation in a long ***,the planet is easily swallowed and the period differences are large if the initial rotation period of its host star is ***,we also study the evolution of WASP-19 and estimate the range of tidal quality parameter Q_(*)^(')=(4.6±0.9)×10^(6)and the initial semimajor axis as(0.035±0.004)au.

关键词： stars rotation-stars solar-type-planet-star interactions

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The Progenitors of Type Ia Supernovae with Asymptotic Giant Branch Donors

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Research in Astronomy and Astrophysics 2023年第7期23卷 118-125页

作者： Lu-Han Li Dong-Dong Liu Bo Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China International Centre of Supernovae Yunnan Key LaboratoryKunming 650216China University of Chinese Academy of Sciences Beijing 100049China

TypeⅠa supernovae(SNe Ia)are among the most energetic events in the *** are excellent cosmological distance indicators due to the remarkable homogeneity of their light ***,the nature of the progenitors of SNeⅠa is still not well *** the single-degenerate model,a carbon-oxygen white dwarf(CO WD)could grow its mass by accreting material from an asymptotic giant branch(AGB)star,leading to the formation of SNe Ia when the mass of the WD approaches to the Chandrasekhar-mass limit,known as the AGB donor *** this channel,previous studies mainly concentrate on the wind-accretion pathway for the mass-increase of the *** the present work,we employed an integrated mass-transfer prescription for the semidetached WD+AGB systems,and evolved a number of WD+AGB systems for the formation of SNe Ia through the Roche-lobe overflow process or the wind-accretion *** provided the initial and final parameter spaces of WD+AGB systems for producing SNe *** also obtained the density distribution of circumstellar matter at the moment when the WD mass reaches the Chandrasekhar-mass ***,we found that the massive WD+AGB sample AT 2019qyl can be covered by the final parameter space for producing SNe Ia,indicating that AT 2019qyl is a strong progenitor candidate of SNe Ia with AGB donors.

关键词： stars:evolution (stars:)supernovae:general (stars:)binaries(including multiple):close (stars:)white dwarfs

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