Subjects: Astronomy submitted time 2025-07-02 Cooperative journals: 《天文学进展》
Abstract： High-amplitude δ scuti stars (HADS), a subclass of δ Scuti pulsating variable stars, are characterized by short pulsation periods, large amplitudes, and single or multiple radial pulsation modes, making them an important target for asteroseismology. In this paper, a frequency analysis of three HADS is performed for the first time using the time-series photometry data provided by the Transiting Exoplanet Survey Satellite (TESS). The result show that TIC 355547586 pulsates at the fundamental frequency and first overtone, and TIC 358502706 at the fundamental frequency, first and third overtone. Non-radial pulsation frequencies were also detected in their frequency spectra. TIC 260654645 is pulsating at fundamental frequency and first overtone. The phase-folding curve of the source has a clear bulge in the brightness-decreasing phase near the luminosity minima, exhibiting the characteristics of a ab-type RR Lyrae, and the period ratio of the first overtone to the fundamental frequency of it is larger than the theoretical prediction for radial pulsation, which, combined with its positional deviation from the HADS pulsation instability band on the Hertzsprung-Russell diagram, makes the star worthy of further study.
Subjects: Astronomy submitted time 2025-04-02 Cooperative journals: 《天文学进展》
Abstract： The galactic bar is a ubiquitous morphological structure in the nearby universe. There is an interaction between the bar and the host galaxy, which affects the physical properties of the host galaxy and drives secular evolution in the host galaxy. In recent years, many important progress on the evolutionary relationship between bars and galaxies have been made in observational studies. The research and identification methods of bars tend to be diversified, and the influence of bars on the evolution of galaxies and the physical mechanism are becoming more and more complete. Firstly, the influence of bars on the evolution of galaxies is introduced, and the emphasis is the effect of bars on the formation of stars in galaxies. Secondly, the distribution of bars in galaxies is analyzed, while the characteristics of barred spiral galaxies and the evolution of bars with red shift are described. Then, several main methods for identifying bars are summarized and discussed. Finally, the research on the relationship between bars and galaxies is summarized and prospected.
Subjects: Astronomy submitted time 2025-04-02 Cooperative journals: 《天文学进展》
Abstract： The standard cosmological model has become one of the most successful frameworks for explaining and predicting the formation and evolution of large-scale structures. Over the past few decades, numerical simulations based on the standard cosmological model have deepened our understanding of cosmic structures and galaxy formation, serving as a bridge between theoretical research and observational data. The Milky Way, as the most familiar and extensively observed galaxy, provides valuable samples for studying the galaxy formation and evolution. The article reviews the current status of numerical simulations of the Milky Way over the past decade. First, it introduces the cosmological background of large-scale structures and the numerical techniques of N -body simulations. It then discusses theoretical models of galaxy formation and methods of hydrodynamics simulations, detailing the impact of baryonic physics mechanisms on galaxy evolution and the numerical subgrid models. Subsequently, it focuses on zoom-in techniques for simulating the Milky Way and some popular Milky Way simulation projects, as well as the latest progress in using Milky Way simulations to study small-scale issues. Finally, the article concludes with a summary and outlook on the future of Milky Way simulations.
Subjects: Astronomy submitted time 2024-12-31
Abstract： The SAGES survey is a northern sky photometric survey conducted by multiple telescopes with different capabilities at different stations, and it is currently being advanced. At present, there are many photometric surveys worldwide, and most of them have corresponding observation strategies. In order to ensure the effective achievement of SAGES survey scientific goals and implement the survey observation strategy, we have developed a survey observation schedule software. The software runs well in practice and strongly supports the survey observation. This article introduces the observation strategy, software structure, schedule software functions, usage, and output results of the SAGES survey. Furthermore, this program is still supporting the observations of the SAGES survey.
Peer Review Status:
Awaiting Review
Subjects: Astronomy submitted time 2024-10-10 Cooperative journals: 《天文学进展》
Abstract： The monitoring of transient sources such as variable stars and extrasolar planets yields a significant volume of imaging data. Timely reduction of the data, producing light curves and triggering transient event are pivotal for advancing research in this field. Focus#2;ing on a group of meter-class optical telescopes located at the Xinglong Observatory of the National Astronomical Observatories of Chinese Academy of Science, an automatic pipeline to reduce time-series raw images and generating normalized differential photometric light curves named PPCLP is built and introduced in this paper. The program is modular, uni#2;versal, and easy to use, making it adaptable across various operating systems. Employing an improved differential photometric method, PPCLP achieves a differential photometric accu#2;racy of 10−3 . In addition to its compatibility with equatorial telescopes, PPCLP seamlessly processes field-uncorrected images acquired from altazimuth telescopes. The components, features, and usage of the program are described in detail in this paper. A brief introduction on how to use the program is presented using the data obtained from the 60 CM Telescope at the Xinglong Observatory for the variable star V670 And. Lastly, this paper discusses the limitations of the program and outlines potential avenues for future development.
Subjects: Astronomy submitted time 2024-10-10 Cooperative journals: 《天文学进展》
Abstract： Space objects frequently appear as elongated stripe patterns, known as streaks, in optical images. The accurate detection of streaks is of great significance for the recogni#2;tion and measurement of space objects. In recent years, many researchers have studied the detection methods of space object streaks and achieved fruitful results. With the improve#2;ment of the detection ability of space objects, the detection of faint streaks has become more and more important in realizing comprehensive and accurate space object detection. This paper provides an overview of the main principles and steps of space object streak detec#2;tion methods in optical images. It classifies and summarizes these methods based on their characteristics, and selects four representative single-frame image-based algorithms for space object streak detection from different categories. Experimental comparisons of these four methods are conducted using both simulated and measured images. Based on the experi#2;mental results, the advantages and disadvantages of each method are analyzed. Finally, the future development directions of streak detection methods in optical images are prospected.
Subjects: Astronomy submitted time 2024-07-03 Cooperative journals: 《天文学进展》
FANG Wen-feng
YAO Song
YU Yong
WANG Lei
SHAN Xing-mei
SHEN Lu-run
WANG Qi
CHEN Zhen-dong
LIN Qing
DU Zhi-mao
YAO Jia-wen
Abstract： The Double-focus One-meter Telescope, located at the Wangshu Observatory of the Shanghai Astronomy Museum, is currently the largest aperture telescope dedicated to popular science in China. The telescope adopts a dual-focus design scheme that allows manual switching between the prime and Nasmyth focus. The Nasmyth focus primarily serves visual observations for popular science, while the prime focus is equipped with a scientific-grade CMOS sensor, offering a field of view of 1.5 ◦ × 1.1 ◦ . The larger field of view is suitable not only for live broadcast events but also for extensive research on various topics such as surveys of novae and supernovae, investigations of small celestial bodies in the solar system, and monitoring of artificial satellites. The astrometric precison at the prime focus of the telescope was analyzed and evaluated based on actual observation data. The results indicate that for star images with a signal-to-noise ratio greater than 5, the repeatability of measured coordinates is better than 0.1 pixel. When the signal-to-noise ratio is 30, the repeatability improves to better than 0.05 pixel. Using the high-precision Gaia DR3 catalog as the reference, the analysis reveals the presence of significant non-linear characteristics in the observation images obtained at the prime focus of the telescope. Consequently, a 3-order model (20-parameter) is necessary for data reduction. For the test observation data, the observational precision for stars brighter than 15th magnitude is approximately 0.05′′ , with the precision decreasing gradually as the magnitude becomes fainter. The observational precision for 17.5th magnitude is around 0.1′′ .
Subjects: Astronomy submitted time 2024-07-03 Cooperative journals: 《天文学进展》
Abstract： The annual signals in the Global Navigation Satellite System (GNSS) surface deformation time series include not only load deformation but also thermal expansion caused by the change of Earth’s surficial temperature. Using a global three-dimensional thermoe#2;lastic deformation model, the thermal expansion effects of 39 crustal movement observation network of China (CMONOC) stations in the U, E, and N directions in southwestern China are estimated. Then the consistency between GNSS time series (before and after correcting thermal expansion effects) and load deformation derived from satellite gravity observations is analyzed, by comparing GNSS results with the calculations from Gravity Recovery and Climate Experience (GRACE) and GRACE Follow-On (GRACE-FO). After correcting for thermal expansion effects, the results indicate that the correspondence between the vertical component (U direction) of GNSS and the GRACE/GRACE-FO results is slightly weakened. On the horizontal component, the consistence in the E direction improves to some extent, but there exists a significant decrease in the N direction. The results presented in this paper in the southwest region are inconsistent with existing global or large-scale regional studies, indicating that the accuracy of estimating thermal expansion effects in different regions by using global thermoelastic deformation models needs to be further evaluated, and its impact on three-dimensional surface deformation is also worth further in-depth research.
Subjects: Astronomy submitted time 2024-07-03 Cooperative journals: 《天文学进展》
Abstract： We have collected and analyzed the limited the Very Large Array (VLA) archival data of J1458+4121, which is a possible candidate of neutrino event IC-220624A, based on which we observed the source first time with the Very Long Baseline Array (VLBA) at L and C bands. Through data processing and analysis, we obtained the VLBA images of J1458+4121. In addition, its more precise coordinate (α=14:58:20.772, δ=41:21:01.911) was obtained by phase reference technique. The total flux density observed by VLA decreases from 1.4 to 8.4 GHz, so its radio spectrum may be power-law. However, the total flux density observed by VLBA shows an increasing trend from 1.5 to 5 GHz, which means an inversted spectrum in the GHz band. Therefore, it is highly likely that J1458+4121 is a young radio source, and its neutrino production may be caused by the emergence of a new jet component. The results of this paper are beneficial to the follow-up study of J1458+4121, and extend the focus on neutrino origin from bright blazars to other types of active galactic nuclei.
Subjects: Astronomy submitted time 2024-04-12 Cooperative journals: 《天文学报》
KANG Zhe
NIU Bing-li
LI Zhen-wei
SUN Jian-nan
LV You
ZHU Cheng-wei
DENG Shi-yu
LIU De-long
YANG Wen-bo
ZHANG Nan
LIU Ming
SUN Ming-guo
LIU Cheng-zhi
Abstract： Ground-based optical astronomical telescopes are one of the most important instruments for human exploration and research of the universe. Monitoring and analysis of the optical observation environment of the existing ground-based optical station can provide a reference for the targeted modification of equipment and the adjustment of observation strategies of observers, which is of great significance for improving the observation efficiency of ground-based optical equipment. Jilin Astronomical Observatory (hereinafter referred to as the ``Base'') is located about 5 kilometers (126.3$^{\circ}$ E, 43.8$^{\circ}$ N, 313 meters above sea level) in Nangou, Xiaosuihe Village, Dasuihe Town, Jilin City, Jilin Province, which is affiliated to the Changchun Observatory, National Astronomical Observatories, Chinese Academy of Sciences. The mean value of seeing of the base is about 1.3$''$--1.4$''$, the night sky brightness in the V band near the zenith is 20.64\;mag\,$\cdot$\,arcsec$^{-2}$, and the maximum number of clear nights is better than 270 days per year, which shows the good astronomical observation conditions. Jilin Astronomical Observatory, which was put into operation in 2016, has several photoelectric telescopes, including the 1.2-meter photoelectric telescope, the Mini Optoelectronic Telescope Array, the large field of view photoelectric telescope array, and the advanced multi-functional array-structured photoelectric detector. With the equipments mentioned above, we have carried out relevant research mainly on space target detection and recognition, precision orbit determination, new photoelectric detection methods and multicolor photometry of variables, and so forth. We have maintained a good cooperative relationship with a number of domestic universities and scientific research institutes.
Subjects: Astronomy submitted time 2024-01-05 Cooperative journals: 《天文学进展》
Abstract： Since the first detection of GW150914, a larger amount of stellar binary black hole (sBBH) mergers have been detected by LIGO/Virgo collaboration with high confidence. By analyzing the gravitational wave (GW) signals, one can obtain crucial physical properties of these sBBH mergers, including their chirp mass, spin, and luminosity distance, etc. The origin of sBBHs may encode in the distribution of these physical properties. Here, the curent status of the study on sBBHs spins is reviewed. First, various formation mechanisms of sBBHs are briefly introduced, and these mechanisms include: 1) sBBHs are formed via the evolution of massive binary stars (EMBS channel); 2) sBBHs are formed via the dynamical interactions with surrounding (compact) stars in dense stellar clusters (dynamical channel); etc. The origin of spins for sBBHs originated from the black hole formation processes is also introduced. One may expect that the spin distributions resulting from different sBBH formation channels are different. For example, the two components of each sBBH resulting from the EMBS channel have spins more or less aligned with each other, while they may be randomly distributed if the sBBH is resulting from the dynamical channel. Therefore, the spin distribution obtained from GW observations may be used to distinguish the EMBS channel from the dynamical channel and further reveal the origin of sBBHs. The general methods for constraining the origin of sBBHs via their spin distribution are then introduced. The results obtained by recent works using the GW observations of sBBHs (GWTC) are summarized. Finally, a summary and a short prospect are given for the future demography study of the sBBH spins measured by next generation ground-based GW detectors.
Subjects: Astronomy submitted time 2023-12-15 Cooperative journals: 《天文学报》
Abstract： Hydrogen masters have high short-term stability, using them as master clocks can generate high-precision local standard time in a short period of time. However, the hydrogen maser has a frequency drift phenomenon, which leads to its poor long-term stability, thus affecting the accuracy of the local time. The rotation of the millisecond pulsar is highly stable. With the help of its high long-term stability, it can regularly control the frequency of the hydrogen atomic clock, thus control the real-time signal. The stability of four millisecond pulsars in the second data set released by the International Pulsar Timing Array (IPTA) is analyzed. At the same time, the frequency stability of a hydrogen maser of the National Time Service Center (NTSC) is analyzed by Hadamard variance. Finally, a strategy for steering the frequency of hydrogen master using pulsars is given.
Subjects: Astronomy submitted time 2023-12-13 Cooperative journals: 《天文学进展》
Abstract： Sequoia is a retrograde substructure from the accretion event. This paper illus#2;trates the discovery, the criterion of member determination and the chemical properties of this substructure. Moreover, using the data information provided by LAMOST DR8 and Gaia, we compared the chemical abundance of Sequoia and GES according to the previous member star selection criteria. It was found that different selection criteria would affec#2;t the analysis to some extent, but there was no obvious boundary between the chemical abundances of Sequoia and GES. Meanwhile, we used the HDBSCAN clustering algorithm to select the kinematics of the clumps, further analyzed the chemical abundance of the clumps, and obtained a more obvious distribution of Sequoia than the previous comparison. However, we still could not clearly separate the Sequoia and GES from the chemical abundance using the abundance from low#2;resolution spectra. High resolution spectra data and more accurate selection criteria for further analysis are needed.
Subjects: Astronomy submitted time 2023-12-13 Cooperative journals: 《天文学进展》
Abstract： The Earth orientation parameters (EOP) is the bridge between the Earth refer#2;ence frame and the geocentric celestial reference frame, and it is an indispensable important parameter in the process of satellite precise orbit determination. Taking the EOP parameters provided by the International Earth Rotation Service and the Shanghai Astronomical Ob#2;servatory as examples, this paper analyzes the relationship between the orbit determination residuals, orbit determination accuracy, and EOP prediction capability under the Beidou-3 regional network observation mode and the satellite-ground inter-satellite joint observation mode. The research shows that for the products provided by IERS, the prediction error has little effect on the orbit determination accuracy of the regional station-only orbit deter#2;mination model, but its 10-day prediction error has an decimeter-level impact on the orbit determination accuracy of the satellite-Earth-satellite joint orbit determination model. For the products provided by the Shanghai Astronomical Observatory, the orbit determination accuracy of the two orbit determination modes gradually decreases with the increase of the EOP forecast days. In addition, the orbit determination accuracy of different products in the satellite-Earth inter-satellite joint orbit determination mode is smaller than that in the orbit determination mode only under regional network monitoring, indicating that the addition of inter-satellite links can reduce the EOP of satellite orbit determination. Dependence on forecast errors. This research is of great significance to the realization of satellite precise orbit determination engineering under regional observation conditions.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-12-06 Cooperative journals: 《天文研究与技术》
Abstract： We conducted a test using the popular science telescope, Sky-Watcher 150PDS, and the amateur-grade ZWO ASI120MM-S CMOS camera to explore the feasibility of using popular science equipment for professional astronomical observation and scientific research. Initially, we evaluated the basic performance and parameter curves of the CMOS camera, which met the fundamental requirements for professional astronomical observation. Subsequently, we installed the CMOS camera on the Sky-Watcher telescope and performed basic astronomical observations at the Xinglong Observatory, NAOC. We observed the open cluster M35 and the short-period variable star V∗V2455 Cyg, while acquiring the necessary photometric auxiliary images (bias and flat). The acquired data underwent professional astronomical image processing techniques, including astrometric calibration, aperture photometry, and flux calibration. This allowed us to obtain the photometric data, light curve, and performed a simple period analysis for the observed targets. By comparing our photometric results with known star catalogs, we determined that the photometric precision of our system exceeded 0.02 mag, with a differential photometric precision of approximately 0.005 mag. These results demonstrate the capability of popular science telescopes and CMOS cameras for conducting astronomical observations and research. Consequently, this opens opportunities for primary and secondary school students as well as astronomy enthusiasts to actively participate in astronomical scientific observation and research.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-10-23 Cooperative journals: 《天文研究与技术》
Abstract： The 1 m New Vacuum Solar Telescope (NVST) is capable of high-resolution imaging observations better than 0.2″, but cannot yet routinely observe high-resolution magnetic fields. Many magnetic structures and solar activity exist at small scales, requiring high-resolution magnetic field observations. NVST offers excellent seeing, and if the magnetometer has fast modulation capabilities and is coupled with statistical reconstruction techniques, it is expected to achieve high-resolution solar magnetic field measurements. The main problems faced by NVST in measuring magnetic fields include time-varying polarisation due to bending-axis optical paths, optical axis shifts due to telescope attitude changes and wind loading, and the effects of turbulence. In this paper, we analyze in detail the requirements for high-resolution observation of the solar magnetic field and the solar magnetic field measurement problems faced by NVST, formulate the basic parameters of the magnetometer, propose the requirements for the polarisation analyzer, and design a high-resolution observation scheme for the photospheric magnetic field. Finally, the optical path for the magnetometer is designed using ZEMAX optical design software, and the results show that the optical design can meet the requirements of high-resolution imaging.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-10-23 Cooperative journals: 《天文研究与技术》
Abstract： The magnetic imager of ground-based solar telescope will be affected by atmospheric turbulence during polarimetry, resulting in inaccurate measurement results. By synchronously detecting the wavefront aberration, and to use deconvolution reconstruction of the sun′s narrow band polarization image, the poor photons problem caused by the narrow band filter can be overcome. The high-resolution image reconstruction algorithm is applied to the reconstruction of the sun′s polarized image. During the reconstruction process, inaccurate wavefront sensing result can lead to I crosstalk between the reconstructed polarization image and the real polarization signal, resulting in certain difference. To study the impact of wavefront sensing accuracy on polarization image reconstruction accuracy during the reduction, a simulation model is established in this paper to study the I crosstalk of polarimetry results under different seeing and wavefront sensing accuracy. The results indicate that the reconstruction quality of polarized images is positively correlated with the accuracy of wavefront sensing. Under certain conditions, increasing the number of frames used for image reconstruction and reducing image resolution can also reduce the I→QUV crosstalk.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-10-18 Cooperative journals: 《天文研究与技术》
Abstract： Type II radio bursts are the best tracers of Coronal Mass Ejections (CME). The coronal or interplanetary shocks are generated along with a dramatic effect on the Earth′s magnetosphere, when CME exceed the local Alfin velocity. The detection of type II radio bursts in the radio band manifests the generation of coronal shock waves. The prediction of the arrival time of shock waves to the Earth is essential to the space weather prediction. Type II radio burst was detected for the first time by Qitai low frequency (Qitai LFRA) at around 06:20 UT on September 28, 2021, with a frequency coverage of 18-50 MHz and a duration of more than 10 minutes. Since virtually no observation with effective spatial resolution have been made at extremely low frequency (<40 MHz) band, there is a great possibility to discover unknown phenomena at this band in future. Our observation shows that Qitai LFRA has good performance (Typical gain: 6 dBi) and high sensitivity(-78 dBm/125 kHz, DR: 72 dB), and can play a unique role in the 25th annual solar activity peak.
Subjects: Astronomy submitted time 2023-10-07 Cooperative journals: 《天文学报》
Abstract： In order to improve the reliability of the time transfer link, Bureau International des Poids et Mesures (BIPM) has officially taken the Galileo time comparison as the backup link for UTC calculation since 2020. Therefore, the delay calibration of the Galileo signal of the receiver is a necessary work for all time-keeping labs around the world to participate in the UTC link. Taking the GPS link calibrated by Physikalisch-Technische Bundesanstalt (PTB) and the National Time Service Center (NTSC) as a reference, this paper sets PT09 receiver as a reference station to calibrate and verify the total Galileo E3 (Galileo E1\&E5a) delay of NT02 and NT05 receivers of NTSC. The results show that the total Galileo E3 delays of NT02 and NT05 are 74.6\;ns and 46.5\;ns respectively, the calibration uncertainty is 3.5\;ns, and the calibration delay is relatively stable. After calibration, the results of GPS P3 and Galileo E3 common view comparison between NT02 and NT05 receivers of NTSC and calibrated receivers of other time-keeping labs are basically consistent. Taking the comparison results of GPS P3 links between NTP3 and receivers of other labs as a reference, the average deviation is less than 1.5\;ns, which is within the calibration uncertainty.
Subjects: Astronomy >> Astrophysical processes submitted time 2022-11-22 Cooperative journals: 《天文研究与技术》
Abstract： Timekeeping atomic clocks mainly include hydrogen masers and cesium atomic clocks. In order to further explore the time-scale performance of different types of timekeeping atomic clocks, this paper carried out a study on the hydrogen maser and the hydrogen-cesium combined time scale . Firstly, the hydrogen maser was classified according to the d bulletin issued by BIPM. According to the classification results, the atomic time-scale theory is used to calculate the hydrogen maser time scale, and the analysis results are given. Then the time scales of cesium clocks are calculated and two different time scales of hydrogen-cesium combined ensembles are analyzed and explored. The results show that the time-scale fluctuation range of the hydrogen maserensemble based on the small frequency drift is smaller, and the stability is better than the time scale of the hydrogen maserensemble based on the larger frequency drift. The time scale stability of the hydrogen-cesium combination is better than the total cesium clock, and the result of different hydrogen-cesium combination time scale clocks are similar.
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