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Predict the spatiotemporal distribution of solar magnetic field and understand the evolutionary feature of solar activity

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Science China Earth Sciences 2024年第8期67卷 2702-2704页

作者： Jingxiu WANG national astronomical observatories Chinese Academy of SciencesBeijing 100101China

Solar activities are closely related to human production and daily *** warm sunlight nurtures life on Earth,but the Sun also occasionally exhibits eruptive activities that significantly impact and threaten the Earth’s *** eruptive activities occur as large-scale energy release processes in localized regions of the solar atmosphere,primarily manifested through the enhanced electromagnetic radiation and energetic particle emissions in solar flares,as well as the ejection of mass and magnetic flux in coronal mass ejections(CMEs).

关键词： Solar Earth evolutionary

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Pulsations of Three Rapidly Oscillating Ap Stars TIC 96315731, TIC72392575, and TIC 318007796

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Research in Astronomy and Astrophysics 2024年第8期24卷 159-170页

作者： Hai-Jian Zhong Dong-Xiang Shen Chun-Hua Zhu He-Lei Liu Su-Fen Guo Guo-Liang Lü School of Physical Science and Technology Xinjiang University Xinjiang astronomical Observatory National Astronomical ObservatoriesChinese Academy of Sciences

We analyze the frequencies of three known roAp stars,TIC 96315731,TIC 72392575,and TIC 318007796,using the light curves from the Transiting Exoplanet Survey *** TIC 96315731,the rotational and pulsational frequencies are 0.1498360 day-1and 165.2609 day-1,*** the case of TIC 72392575,the rotational frequency is 0.25551 *** detect a quintuplet of pulsation frequencies with a center frequency of135.9233 day-1,along with two signals within the second pair of rotational sidelobes of the quintuplet separated by the rotation *** two signals may correspond to the frequencies of a dipole *** TIC318007796,the rotational and pulsational frequencies are 0.2475021 day-1,192.73995 day-1,and196.33065 day-1,*** on the oblique pulsator model,we calculate the rotation inclination （i）and magnetic obliquity angle （b） for the stars,which provide the geometry of the pulsation *** the phases of the frequency quintuplets,the pulsation amplitude and phase modulation curves,and the results of spherical harmonic decomposition,we conclude that the pulsation modes of frequency quintuplets in TIC96315731,TIC 72392575,and TIC 318007796 correspond to distorted dipole mode,distorted quadrupole mode,and distorted dipole mode,respectively.

关键词： asteroseismology stars: chemically peculiar stars: oscillations (including pulsations) techniques: photometric

The FAST all sky HI survey(FASHI):The first release of catalog

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 112-133页

作者： Chuan-Peng Zhang Ming Zhu Peng Jiang Cheng Cheng Jing Wang Jie Wang Jin-Long Xu Xiao-Lan Liu Nai-Ping Yu Lei Qian Haiyang Yu Mei Ai Yingjie Jing Chen Xu Ziming Liu Xin Guan Chun Sun Qingliang Yang Menglin Huang Qiaoli Hao FAST Collaboration Guizhou Radio astronomical Observatory Guizhou UniversityGuiyang 550000China national astronomical observatories Chinese Academy of Sciences(CAS)Beijing 100101China Chinese Academy of Sciences South America Center for Astronomy National Astronomical ObservatoriesCASBeijing 100101China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The FAST All Sky HI survey(FASHI)was designed to cover the entire sky observable by the Five-hundred-meter Aperture Spherical radio Telescope(FAST),spanning approximately 22000 square degrees of declination between-14°and+66°,and in the frequency range of 1050-1450 MHz,with the expectation of eventually detecting more than 100000 HI *** August 2020 and June 2023,FASHI had covered more than 7600 square degrees,which is approximately 35%of the total sky observable by *** has a median detection sensitivity of around 0.76 m Jy beam-1and a spectral line velocity resolution of~6.4 km s-1at a frequency of~1.4 *** of now,a total of 41741 extragalactic HI sources have been detected in the frequency range 1305.5-1419.5 MHz,corresponding to a redshift limit of z■*** cross-matching FASHI sources with the Siena Galaxy Atlas(SGA)and the Sloan Digital Sky Survey(SDSS)catalogs,we found that 16972(40.7%)sources have spectroscopic redshifts and 10975(26.3%)sources have only photometric *** of the remaining 13794(33.0%)HI sources are located in the direction of the Galactic plane,making their optical counterparts difficult to identify due to high extinction or high contamination of Galactic stellar *** on current survey results,the FASHI survey is an unprecedented blind extragalactic H I *** has higher spectral and spatial resolution and broader coverage than the Arecibo Legacy Fast ALFA Survey(ALFALFA).When completed,FASHI will provide the largest extragalactic HI catalog and an objective view of HI content and large-scale structure in the local universe.

关键词： surveys redshifts galaxies telescope radio lines HI line

Four Late-type Galaxies with Double Radio Lobes and Properties of Such Galaxies

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Research in Astronomy and Astrophysics 2024年第4期24卷 84-90页

作者： Z.S.Yuan X.Y.Gao Z.L.Wen J.L.Han national astronomical observatories Chinese Academy of SciencesBeijing 100101China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China

The triggering mechanism for radio lobes from late-type galaxies is not fully *** samples are desired for a thorough investigation and *** utilizing the optical data from the newly released Dark Energy Spectroscopic Instrument imaging surveys and the radio sources from the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-centimeter,we identify four Late-type Galaxies with double Radio Lobes(La GRLs):J0217-3645,J0947+6220,J1412+3723 and J1736+*** previously known La GRLs,we confirm the correlation between radio power P_(1.4GHz)and stellar mass M_(*)of host ***(25/35)La GRLs belong to the blue cloud galaxies,while the newly identified cases in this work are located within the region of the red *** find a clear correlation between the differential radio power,i.e.,the offset from the P_(1.4GHz)-M_(*)relation,and the galaxy color,indicating that bluer galaxies at a fixed M_(*)tend to host more powerful radio ***,the majority(31/36)of La GRLs are either located in a galaxy group or displaying a disturbed *** suggest that all of the galaxy mass,color and surrounding environment could play important roles in triggering radio lobes in late-type galaxies.

关键词： galaxies:active galaxies:jets galaxies:spiral radio continuum:galaxies

Progress on SVOM Satellite Development

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空间科学学报 2024年第4期44卷 690-691页

作者： WEI Jianyan national astronomical observatories Chinese Academy of SciencesBeijing 100101

SVOM(Space-based multiband Variable Object Monitor)is a Chinese-French space mission mainly designed to study Gamma-Ray *** satellite carries four instruments to detect and localize the prompt GRB emission and measure the evolution of the afterglow in the visible band and in soft X-rays,and a VHF communication system enables the fast transmission of SVOM alerts to the *** ground segment includes an array of wide-angle cameras and two follow-up *** was launched into an orbit of about 635 km on 22 June 2024,with three years of nominal operations and an extension of two years.

关键词： Space astronomy Gamma-ray burst

Derivative Spectroscopy and its Application at Detecting the Weak Emission/Absorption Lines

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Research in Astronomy and Astrophysics 2024年第3期24卷 205-223页

作者： Lihuan Yu Jiangdan Li Jinliang Wang Jiajia Li Jiao Li Qiang Xi Zhanwen Han Yunnan observatories Chinese Academy of Sciences(CAS)Kunming 650011China Key Lab of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

The development of spectroscopic survey telescopes like Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),Apache Point Observatory Galactic Evolution Experiment and Sloan Digital Sky Survey has opened up unprecedented opportunities for stellar *** types of stars,such as early-type emission-line stars and those with stellar winds,can be distinguished by the profiles of their spectral *** this paper,we introduce a method based on derivative spectroscopy(DS)designed to detect signals within complex backgrounds and provide a preliminary estimation of curve *** method exhibits a unique advantage in identifying weak signals and unusual spectral line profiles when compared to other popular line detection *** validated our approach using synthesis spectra,demonstrating that DS can detect emission signals three times fainter than Gaussian ***,we applied our method to 579,680 co-added spectra from LAMOST Medium-Resolution Spectroscopic Survey,identifying 16,629 spectra with emission peaks around the Hαline from 10,963 *** spectra were classified into three distinct morphological groups,resulting in nine subclasses as follows.(1)Emission peak above the pseudo-continuum line(single peak,double peaks,emission peak situated within an absorption line,P Cygni profile,Inverse P Cygni profile);(2)Emission peak below the pseudo-continuum line(sharp emission peak,double absorption peaks,emission peak shifted to one side of the absorption line);(3)Emission peak between the pseudo-continuum line.

关键词： line identification-line profiles-methods data analysis-techniques spectroscopic-techniques radial velocities

Toward a Direct Measurement of the Cosmic Acceleration: The Pilot Observation of HI 21 cm Absorption Line at FAST

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Research in Astronomy and Astrophysics 2024年第7期24卷 50-58页

作者： Jiangang Kang Chang-Zhi Lu Tong-Jie Zhang Ming Zhu Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University School of Physics and Astronomy Beijing Normal University national astronomical observatories Chinese Academy of Sciences

This study presents results on detecting neutral atomic hydrogen（H I） 21 cm absorption in the spectrum of PKS PKS1413+13 at redshift z = 0.24670041. The observation was conducted by FAST, with a spectral resolution of10 Hz, using 10 minutes of observing time. The global spectral profile is examined by modeling the absorption line using a single Gaussian function with a resolution of 10 kHz within a 2 MHz bandwidth. The goal is to determine the rate of the latest cosmic acceleration by directly measuring the redshift evolution of the H I 21 cm absorption line with Hubble flow toward a common background quasar over a decade or longer time span. This will serve as a detectable signal generated by the accelerated expansion of the Universe at redshift z < 1, referred to as redshift drift z（5） or the SL effect. The measured H I gas column density in this DLA system is approximately equivalent to the initial observation value, considering uncertainties of the spin temperature of a spiral host galaxy. The high signal-to-noise ratio of 57,obtained at a 10 kHz resolution, strongly supports the feasibility of using the H I 21 cm absorption line in DLA systems to accurately measure the redshift drift rate at a precision level of around 10-10per decade.

关键词： (cosmology:) cosmological parameters (cosmology:) dark energy cosmology: observations cosmology: theory ISM: clouds radio lines: galaxies radio lines: ISM

Real-time Abnormal Detection of GWAC Light Curve based on Wavelet Transform Combined with GRU-Attention

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Research in Astronomy and Astrophysics 2024年第5期24卷 151-168页

作者： Hao Li Qing Zhao Long Shao Tao Liu Chenzhou Cui Yunfei Xu College of Artifcial Intelligence Tianjin University of Science and TechnologyTianjin 300457China national astronomical observatories Chinese Academy of SciencesBeijing 100101China

Nowadays, astronomy has entered the era of Time-Domain Astronomy, and the study of the time-varying light curves of various types of objects is of great significance in revealing the physical properties and evolutionary history of celestial bodies. The Ground-based Wide Angle Cameras telescope, on which this paper is based, has observed more than 10 million light curves, and the detection of anomalies in the light curves can be used to rapidly detect transient rare phenomena such as microgravity lensing events from the massive data. However, the traditional statistically based anomaly detection methods cannot realize the fast processing of massive data. In this paper, we propose a Discrete Wavelet(DW)-Gate Recurrent Unit-Attention(GRU-Attention) light curve warning model. Wavelet transform has good effect on data noise reduction processing and feature extraction, which can provide richer and more stable input features for a neural network, and the neural network can provide more flexible and powerful output model for wavelet transform. Comparison experiments show an average improvement of 61% compared to the previous pure long-short-term memory unit(LSTM) model, and an average improvement of 53.5% compared to the previous GRU model. The efficiency and accuracy of anomaly detection in previous paper work are not good enough, the method proposed in this paper possesses higher efficiency and accuracy,which incorporates the Attention mechanism to find out the key parts of the light curve that determine the anomalies. These parts are assigned higher weights, and in the actual anomaly detection, the star is detected with83.35% anomalies on average, and the DW-GRU-Attention model is compared with the DW-LSTM model, and the detection result f1 is improved by 5.75% on average, while having less training time, thus providing valuable information and guidance for astronomical observation and research.

关键词： methods data analysis-stars variables general-techniques photometric

Long-term Evolution of Solar Activity and Prediction of the Following Solar Cycles

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Research in Astronomy and Astrophysics 2024年第3期24卷 194-204页

作者： Pei-Xin Luo Bao-Lin Tan national astronomical observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

Solar activities have a great impact on modern high-tech systems,such as human aerospace activities,satellite communication and navigation,deep space exploration,and related scientific ***,studying the long-term evolution trend of solar activity and accurately predicting the future solar cycles are highly *** on the wavelet transform and empirical function fitting of the longest recorded data of the annual average relative sunspot number(ASN)series of 323 yr to date,this work decisively verifies the existence of the solar century cycles and confirms that its length is about 104.0 yr,and the magnitude has a slightly increasing trend on the timescale of several hundred *** on this long-term evolutionary trend,we predict solar cycles 25 and26 by using phase similar prediction *** for solar cycle 25,its maximum ASN will be about146.7±33.40,obviously stronger than solar cycle *** peak year will occur approximately in 2024,and the period will be about 11±1 *** for solar cycle 26,it will start around 2030,and reach its maximum between2035 and 2036,with maximum ASN of about 133.0±3.200,and period of about 10 yr.

关键词： Sun activity-Sun evolution-(Sun) sunspots-methods data analysis