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A correction method for the telluric absorptions and application to Lijiang Observatory

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Research in Astronomy and Astrophysics 2021年第7期21卷 281-289页

作者： Kai-Xing Lu Zhi-Xiang Zhang Ying-Ke Huang An-Bing Ren Liang Xu Hai-Cheng Feng Yu-Xin Xin Xu Ding Xiao-Guang Yu Jin-Ming Bai Yunnan Observatories Chinese Academy of SciencesKunming 650011China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China Department of Astronomy Xiamen UniversityXiamen 361005China Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China Department of Astronomy China West Normal UniversityNanchong 637002China

Observing a telluric standard star for correcting the telluric absorption lines of spectrum will take a significant amount of precious telescope time,especially in the long-term spectral monitoring *** that,it is difficult to select a suitable telluric standard star near in both time and airmass to the scientific *** this paper,we present a method of correcting the telluric absorption lines by combining the advantages of long slit *** rotating the slit,we observed the scientific object and a nearby comparison star in one exposure,so that the spectra of both objects should have the same telluric transmission *** telluric transmission spectrum was constructed by dividing the observed spectrum of the comparison star by its stellar template,and was used to correct the telluric absorption lines of the scientific *** the long slit spectrograph of the Lijiang 2.4-meter telescope,we designed a long-term spectroscopic observation strategy,and finished a four-year spectroscopic monitoring for a pair of objects(an active galactic nucleus and a non-varying comparison star).We applied this method to correct the telluric absorption lines of the long-term monitored spectra by the Lijiang 2.4-meter telescope,and investigated the variation of the telluric absorptions at Lijiang *** found that the telluric absorption transparency is mainly modulated by the seasonal variability of the relative humidity,airmass and *** the scatter of the [O Ⅲ] λ5007 fluxes emitted from the narrow-line region of active galactic nuclei as an indicator,we found that the correction accuracy of the telluric absorption lines is 1%.

关键词： techniques:telluric absorption methods:data analysis techniques:spectroscopic quasars:individual(SDSS J1536+0441)

An explanation for 13 consecutive day activities of Mrk 421

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Research in Astronomy and Astrophysics 2021年第1期21卷 75-86页

作者： Yong-Gang Zheng Chu-Yuan Yang Shi-Ju Kang Jin-Ming Bai Yunnan Observatories Chinese Academy of SciencesKunming 650011China Department of Physics Yunnan Normal UniversityKunming 650092China Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment-Shandong University Weihai 264209China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China Department of Physics and Electronics Science Liupanshui Normal UniversityLiupanshui 553004China

It is surprising to find an instance of migration in the peak positions of synchrotron spectral energy distribution components during the activity epochs of Markarian 421(Mrk 421),accompanying an orphan flare at the X-ray and GeV-TeVγ-ray bands.A geometric interpretation and standard shock or stochastic acceleration models of blazar emission have difficulty reproducing these observed *** present paper introduces a linear acceleration by integrating the reconnection electric field into the particle transport model for the observed behaviors of Mrk *** note that strong evidence for evolution in characteristic of multi-wavelength spectral energy distribution including shifting the peak frequency,accompanying an orphan flare at the X-ray and GeV-TeVγ-ray bands provides an important electrostatic acceleration diagnostic in a blazar *** suitable model parameters,we apply the results of the simulation to the 13-day flaring event in March 2010 of Mrk 421,concentrating on the evolution of multiwavelength spectral energy distribution characteristic by shifting the peak *** is clear that the ratio of the electric field and magnetic field strength plays an important role in temporal evolution of the peak frequency of synchrotron spectral energy distribution *** suggest it is reasonable that the electrostatic acceleration is responsible for the evolution of multi-wavelength spectral energy distribution characteristic by shifting the peak *** on the model results,we assert that the peak frequency of the synchrotron spectral energy distribution component may signify a temporary characteristic of blazars,rather than a permanent one.

关键词： radiation mechanisms:non-thermal BL Lacertae objects:individual:(Mrk 421) acceleration of particles

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

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arXiv 2024年

作者： Li, Xiejin Zhao, Yinghe Bai, Jinming Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China A20 Datun Road Chaoyang District Beijing100101 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

In this paper we investigate the stellar populations and star formation histories of 235 active galactic nuclei (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 (SDSS) Data Release 8. Our results show that the variability sample is the oldest, while the mid-IR sample is the youngest, for which the luminosity at 4020 Å is dominated (> 50%) by the young population (t 8 yr). 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 al. We 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 and 0.1 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 AGN. In addition, we obtain further evidence for a possible suppression of star formation in the host galaxy by the central AGN. We also find that there exists an anti-correlation 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. © 2024, CC BY.

关键词： Active Galactic Nuclei

The C/O ratio of He-accreting carbon-oxygen white dwarfs and type Ia supernovae

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Research in Astronomy and Astrophysics 2020年第1期20卷 19-26页

作者： Xiao Cui Bo Wang Cheng-Yuan Wu Xiang-Cun Meng Zhan-Wen Han Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of the Chinese Academy of Sciences Beijing 100049China

Type Ia supernovae(SNe Ia)are thermonuclear explosions of carbon-oxygen white dwarfs(CO WDs),and are believed to be excellent cosmological distance indicators due to their high luminosity and remarkable ***,there exists a diversity among SNe Ia,and a poor understanding of the diversity hampers the improvement of the accuracy of cosmological distance *** variations of the ratios of carbon to oxygen(C/O)of WDs at explosion are suggested to contribute to the *** the canonical model of SNe Ia,a CO WD accretes matter from its companion and increases its mass till the Chandrasekhar mass limit when the WD *** this work,we studied the C/O ratio for accreting CO *** the stellar evolution code MESA,we simulated the accretion of He-rich material onto CO WDs with different initial WD masses and different mass accretion *** found that the C/O ratio varies for different *** C/O ratio of He-accreting CO WDs at explosion increases with a decreasing initial WD mass or a decreasing accretion *** various C/O ratios may,therefore,contribute to the diversity of SNe Ia.

关键词： stars:evolution supernovae:general white dwarfs

Properties of Interstellar Medium in the S0 Galaxy NGC 1222: Evidence for Shocked-enhanced Line Emission

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arXiv 2025年

作者： Liu, Jiamin Zhao, Yinghe Lu, Kai-Xing Bai, Jin-Ming Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Radio Astronomy and Technology Chinese Academy of Sciences A20 Datun Road Chaoyang District Beijing100101 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

In this paper we present a comprehensive study on the properties of the interstellar medium in NGC 1222, a star-forming early-type merging galaxy that forms a triple system, using optical and far-infrared (FIR) spectroscopic, and multiband photometric data. The fit to the spectral energy distribution reveals a high dust content in the galaxy, with a dust-to-stellar mass ratio of Mdust/M★ ∼ 3.3 × 10−3 that is 40−90 larger than the mean value of local S0 galaxies. By comparing the observed optical emission line ratios to shock models, we suggest that a merger-induced shock, which is further supported by the higher-than-average [O i] 63 µm- and [C ii] 158 µm-to-PAH ratios, plays a role in heating the gas in NGC 1222. We also show evidence for gas inflow by analysing the kinematic properties of NGC 1222. © 2025, CC BY.

关键词： Optical emission spectroscopy

Correcting the Contamination of Second-order Spectra: Improving Hα Measurements in Reverberation Mapping Campaigns

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arXiv 2024年

作者： Xi, Wen-Zhe Lu, Kai-Xing Feng, Hai-Cheng Li, Sha-Sha Bai, Jin-Ming Zhou, Rui-Lei Liu, Hong-Tao Wang, Jian-Guo Yunnan Observatories Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China CAS Key Laboratory of FAST National FAST National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China

Long-term spectroscopic monitoring campaigns on active galactic nuclei (AGNs) provide a wealth of information about its interior structure and kinematics. However, a number of the observations suffer from the contamination of second-order spectra (SOS) which will introduce some undesirable uncertainties at red side of spectra. In this paper, we test the effect of SOS and propose a method to correct it in the time domain spectroscopic data using the simultaneously observed comparison stars. Based on the reverberation mapping (RM) data of NGC 5548 in 2019, one of the most intensively monitored AGNs by Lijiang 2.4-meter telescope, we find that the scientific object, comparison star, and spectrophotometric standard star can jointly introduce up to ∼30% SOS for Grism 14. This irregular but smooth SOS significantly affects the flux density and profile of emission line, while having little effect on the light curve. After applying our method to each spectrum, we find that the SOS can be corrected effectively. The deviation between corrected and intrinsic spectra is ∼2%, and the impact of SOS on time lag is very minor. This method makes it possible to obtain the Hα RM measurements from archival data provided the spectral shape of the AGN under investigation does not have a large change. Copyright © 2024, The Authors. All rights reserved.

关键词： Stars

The progenitors of Type Ia supernovae with asymptotic giant branch donors

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arXiv 2023年

作者： Li, Lu-Han Liu, Dong-Dong Wang, Bo Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China

Type Ia supernovae (SNe Ia) are among the most energetic events in the Universe. They are excellent cosmological distance indicators due to the remarkable homogeneity of their light curves. However, the nature of the progenitors of SNe Ia is still not well understood. In 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 channel. In this channel, previous studies mainly concentrate on the wind-accretion pathway for the mass-increase of the WDs. In 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 process. We provided the initial and final parameter spaces of WD+AGB systems for producing SNe Ia. We also obtained the density distribution of circumstellar matter at the moment when the WD mass reaches the Chandrasekhar-mass limit. Moreover, 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. Copyright © 2023, The Authors. All rights reserved.

关键词： White dwarfs

New multi-color photometric investigations of solar-like contact binary V680 Per

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Research in Astronomy and Astrophysics 2020年第4期20卷 49-56页

作者： Jing-Jing Wang Jia-Jia He Song-Qing Zhao China University of Petroleum–Beijing at Karamay Karamay 834000China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

High-precision CCD photometric observations of the contact binary V680 Per were obtained *** symmetric multi-color light curves were analyzed by using the Wilson–Devinney(2013)*** photometric solutions suggest that V680 Per is an A-type W UMa contact binary with the mass ratio of q=0.693 and a fill-out factor of f=18.84%with a small temperature difference of 101 *** on all minimum times,the O-C curve was analyzed for the first time in this study.A cyclic oscillation(A3=0.00093 d,T3=4.92 yr)superimposed on a secular decrease(d P/dt=-8.16×10-8 d yr-1)was *** continuous decrease in period is possibly a result of mass transfer from the more massive component to the less massive one,or angular momentum loss due to a magnetic stellar *** of this secular decrease,it is predicted that the degree of contact will become higher,and V680 Per will evolve into a deeper overcontact binary.

关键词： binaries:eclipsing stars:solar-type stars:individual(V680 Per)

Observational Properties of 155 β Cephei pulsating variable stars

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arXiv 2024年

作者： Shi, Xiang-Dong Qian, Sheng-Bang Zhu, Li-Ying Li, Lin-Jia Zhao, Er-Gang Lin, Wen-Xu P.O. Box 110 Kunming650216 China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China University of Chinese Academy of Sciences No.1 Yanqihu East Rd Huairou District Beijing101408 China Key Laboratory of the Structure and Evolution of Celestial Objects CAS Kunming650216 China

β Cephei pulsating variable (BCEP) stars are the most massive pulsating variable stars in the main sequence, exhibiting both p- and g-mode pulsations. In this study, we identified 155 BCEP stars or candidates using data from TESS and Gaia, of which 83 were first confirmed as BCEP stars. They have visual magnitudes ranging from 8 to 12 mag and effective temperatures between approximately 20,000 and 30,000 K, while the parallaxes of most targets are between 0.2 and 0.6 mas. The study indicates that these BCEP stars have pulsation periods ranging from 0.06 to 0.31 days, with amplitudes ranging from 0.1 to 55.8 mmag in the TESS band. Additionally, the number of BCEP stars increases as the pulsation amplitude decreases. These targets align with the distribution region of BCEP stars in the luminosity-period (L-P) and temperature-period (T-P) diagrams. We have updated the LP relation of BCEP stars. The Hertzsprung-Russell (H-R) diagram indicates that these targets are in the main-sequence evolutionary phase, with masses ranging from 7 to 20 M☉ and luminosities between 2800 and 71,000 L☉. They are almost in the theoretical instability region of BCEP stars but as previously reported, this region at the low-mass end (red) is not filled. The distribution of the pulsation constant indicates that the dominant pulsation periods of BCEP stars consist mainly of low-order p-mode pulsations with a high proportion of radial fundamental modes. These BCEP stars are excellent objects for enhancing our understanding of the structure and evolution of massive stars through asteroseismology. © 2024, CC BY.

关键词： Giant stars