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Research in Astronomy and Astrophysics 2022年第9期22卷 132-139页

作者： Jia-Wei Hou Shu-Guang Zeng Sheng Zheng Xiao-Yu Luo Lin-Hua Deng Yang-Yang Li Yan-Qing Chen Gang-Hua Lin Yong-Li Feng Jin-Ping Tao Center for Astronomy and Space Sciences China Three Gorges UniversityYichang 443002China College of Science China Three Gorges UniversityYichang 43002China Yunnan Observatories Chinese Academy of SciencesKunming.650216China National Astronomical observatories Chinese Academy of SciencesKunming650216China

The ratio of penumbral to umbra area of sunspots plays a crucial role in the solar physics fields, especially for understanding the origin and evolution of the solar activity cycle. By analyzing the recently digitized sunspot drawings observed from Yunnan Observatories(1957–2021), we investigate the long-term variation of the penumbral to umbra area ratio of sunspots. An automatic extraction method, based on the maximum between-class variance and the morphological discrimination, is used to accurately extract penumbra and umbra and to calculate the ratio over six solar cycles(cycle 19–24). The expected value of the ratio of penumbra to umbra area is found to be 6.63 ± 0.98, and it does not exhibit any systematic variation with sunspot latitudes and phases. The average ratio fluctuates from 5 to 7.5 per year and the overall trend has decreased after 1999 compared to the previous one.The ratio of sunspot penumbra to umbra area satisfies the log-normal distribution, implying that its variation is related to the evolution of the photospheric magnetic field. Our results are consistent with previous works.

关键词： Sun:sunspots Sun:photosphere Sun:activity techniques:image processing

Chinese sunspot drawings and their digitization–(Ⅱ)accuracy analysis for digitized sunspot hand-drawing records of Yunnan Observatories

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Research in Astronomy and Astrophysics 2020年第4期20卷 156-162页

作者： Yang Peng Xiao-Yu Luo Shu-Guang Zeng Lin-Hua Deng Sheng Zheng Gang-Hua Lin Yu-Lin Cheng Jin-Ping Tao Yong-Li Feng College of Science China Three Gorges UniversityYichang 443002China Yunnan Observatories Chinese Academy of SciencesKunming 650216China National Astronomical observatories Chinese Academy of SciencesBeijing 100101China Chongqing University of Arts and Sciences Chongqing 402160China

Sunspots are the most striking and easily observed magnetic structures of the Sun,and statistical analysis of solar historical data could reveal a wealth of information on the long-term variation of solar activity cycle.The hand-drawn sunspot records of Yunnan Observatories,Chinese Academy of Sciences have been accumulating for more than 60 years,and nearly 16000 images have been preserved.In the future,the observation mode of recording sunspots by hand-drawing will be replaced inevitably by digital images observed either at ground or in space.To connect the hand-drawn sunspot data and the purely digital sunspot data in future,it is necessary to analyze the systematic errors of the data which are observed by the two observation modes in the period of transition.In this paper,we choose 268 round sunspots(Htype in modified Zurich sunspot classification)from the drawing of Yunnan Observatories to compare their positions and areas with the CCD observations made by Helioseismic and Magnetic Imager(HMI)on board Solar Dynamic Observatory(SDO)and Global Oscillation Network Group(GONG).We find that the latitude and longitude accuracy of hand-drawn sunspot are within-0.127 and 2.29 degree respectively,and the area accuracy is about 16.36 sunspot unit(μHem).Systematic errors apparently decrease with large sunspot.

关键词： sunspots methods:data analysis techniques:image processing

Preliminary results of CCD observations targeting Himalia acquired at Yunnan Observatories in 2015

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Research in Astronomy and Astrophysics 2016年第12期16卷 59-66页

作者： Huan-Wen Peng Na Wang Qing-Yu Peng Sino-French Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China

In order to study the potential associated with high precision CCD astrometry of irregular satel- lites, we have acquired experimental observations of Himalia, the sixth and irregular satellite of Jupiter. A total of 185 CCD observations were obtained by using the 2.4m and 1 m telescopes administered by Yunnan Observatories over ten nights. Preliminary analysis of the observations were made, including geo- metric distortion, atmospheric refraction, and also the phase effect. All positions of Himalia are measured relative to the reference stars from the catalog UCAC4 in each CCD field of view. The theoretical positions of Himalia were retrieved from the Institute de M6chanique C61este et de Calcul des t^ph6m6rides, while the positions of Jupiter were obtained based on the planetary ephemeris INPOP13c. The results show that the means of observed minus computed （O - C） residuals are -0.004＂ and -0.002＂ in right ascension and declination, respectively. The standard deviations of （O - C） residuals are estimated to be about 0.04＂ in each direction.

关键词： astrometry -- planets and satellites： individual （Himalia） -- methods： observational

FAST unveils a new era in the discovery of long-period pulsars in globular clusters

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 185-186页

作者： Zhanwen Han International Centre of Supernovae Yunnan Key LaboratoryYunnan ObservatoriesChinese Academy of SciencesKunming 650011China

Globular clusters(GC)are among the oldest celestial bodies in the Milky Way.Typically possessing millions of stars and have been going through abundant stellar interactions,GCs are futile ground for hunting for compact objects,particularly,neutron stars.A significant number of fast-spinning millisecond pulsars(MSPs)have been discovered,comprising the majority of known GC pulsars.

关键词： stars pulsars abundant

A Possible X-ray Quasi-periodic Oscillation in the Narrow-line Seyfert 1 Galaxy Mrk 142

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Research in Astronomy and Astrophysics 2024年第6期24卷 193-202页

作者： Xiao-Gu Zhong Jian-Cheng Wang Yong-Yun Chen Xiao-Ling Yu College of Physics and Electronic Engineering Qujing Normal University Yunnan Observatories Chinese Academy of Sciences

A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10-5Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April 11. We find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram, the Weighted Wavelet Z-transform and the REDFIT.We analyze the data in 0.3–0.6 keV, 0.6–1 keV, 1–3 keV and 3–10 keV energy bands, and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV bands. We then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10-5Hz, and use a model to fit them. We find that the QPO signal mainly comes from the X-ray hot corona.

关键词： X-rays: galaxies galaxies: Seyfert accretion accretion disks radiation mechanisms: general LIGHT CURVES SIMILAR-TO-1 HOUR TIME-SERIES BLACK-HOLE VARIABILITY RADIO QPO DISCOVERY EMISSION BINARY

Particle acceleration in the interaction of helical magnetic structure in the flaring coronal loop current sheet: I. Protons and Electrons

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Particle acceleration in the interaction of helical magnetic...

Observational data-driven flood disaster forecasting numerical analysis system for GHM Bay Area: I. Basic algorithm and validation

2022年中国地球科学联合学术年会

作者： BoJing Zhu Yunnan Observatories of CAS

A new nonlinear resonant wave-particle acceleration mechanism in the interaction of helical magnetic structure in large-scale CME/Flare current sheet is proposed in the solar eruption. The original acceleration model assumed helical magnetic structure evolution in the cross-scaling coupling are separated independent process, is known to be important in the helical magnetic structure coalescence and growth process.

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Observational data-driven flood disaster forecasting numeric...

Spectro-polarimetric observations at the NVST:I.instrumental polarization calibration and primary measurements

2022年中国地球科学联合学术年会

作者： BoJing Zhu Yunnan Observatories of CAS

The flooding associated with severe storms in the Guangdong-Hong Kong-Macau Greater Bay Area (GD-HK-MO, GHM Bay), is the most common hazard and occurs nearly annually, requiring the establishment of a flood-risk warning system and prevent injuries and property damage in these areas. In the series studies, a km level-resolution lattice grid (3.7km per lattice) is established to explore the GHM Bay flood disaster forecasting analysis system (21?32′～ 24?26′N, 111?20′～ 115?24′E, 90 × 120 lattices) from hurricane source (the South China Sea, 0? ～ 25?N, 104? ～ 128?E, 750 × 720 lattices).

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Research in Astronomy and Astrophysics 2020年第4期20卷 7-18页

作者： Jun-Feng Hou Zhi Xu Shu Yuan Yu-Chao Chen Jian-Guo Peng Dong-Guang Wang Jun Xu Yuan-Yong Deng Zhen-Yu Jin Kai-Fan Ji Zhong Liu National Astronomical observatories Chinese Academy of SciencesBeijing 100101China Yunnan Observatories Chinese Academy of SciencesKunming 650216China

This paper is devoted to the primary spectro-polarimetric observation performed at the New Vacuum Solar Telescope(NVST)of China since 2017,and our aim is to precisely evaluate the real polarimetric accuracy and sensitivity of this polarimetry by using full Stokes spectro-polarimetric observations of the photospheric line Fe I 532.4 nm.In the work,we briefly describe the salient characteristic of the NVST as a polarimeter in terms of technology and then characterize its instrumental polarization based on the operation in 2017 and 2019.It is verified that the calibration method utilizing the instrumental polarization calibration unit(ICU)is stable and credible.The calibration accuracy can reach up to 3×10^-3.Based on the scientific observation of NOAA Active Region 12645 on 2017 April 5,we estimate that the residual cross-talk from Stokes I to Stokes Q,U and V,after the instrumental polarization calibration,is about 4×10^-3 on average,which is consistent with the calibration accuracy and close to the photon noise.The polarimetric sensitivity(i.e.,the detection limit)for polarized light is of the order of 10-3 with an integration time over 20 s.Slow modulation rate is indeed an issue for the present system.The present NVST polarimeter is expected to be integrated with a high-order adaptive optics system and a field scanner to realize 2 D vector magnetic field measurements in the following instrumentation update.

关键词： techniques:polarimetric techniques:spectroscopic Sun:magnetic fields

Possibility of Searching for Accreting White Dwarfs with the Chinese Space Station Telescope

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Research in Astronomy and Astrophysics 2022年第5期22卷 21-27页

作者： Wei Xie Hai-Liang Chen Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of the Chinese Academy of Sciences Beijing 100049China

Accreting WDs are very important for the studies of binary evolution,binary population synthesis and accretion physics.So far,there are a lot of accreting WD binaries with low accretion rates,such as cataclysmic variables,detected by different surveys.However,few accreting WD binaries with high accretion rates have been detected.In this paper,we studied the spectrum properties of accreting WD binaries and investigated whether accreting WD binaries with high accretion rates can be detected by the Chinese Space Station Telescope(CSST).We found that some accreting WD binaries with high accretion rates can be distinguishable from other types of stars with(NUV-y,u-y),(NUV-r,u-g),(NUV-i,u-g),(NUV-z,u-g)and(NUV-y,u-g)color-color diagrams.Therefore,some accreting WD binaries with high accretion rates can be detected by the CSST.

关键词： white dwarf stars whitedwarfs-binarystars close binarystars-low massstars low-massstar

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

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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 China.yunnan 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 LJT.So we develop an automated data analysis system for the quality control(QC)of YFOSC data.This system is also a new function of the observing support of the YFOSC.Based on the system,YFOSC data can be reduced quickly as they are acquired and QC parameters are extracted.Observers can assess the quality of their data and make a possible revision of their observing plan in time.These parameters can also be used to check the health of the YFOSC,which is helpful for the telescope maintenance team to find potential problems.All of these aim at improving the productivity of the LJT.

关键词： Quick Observer YFOSC