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Using CSST and ejecta-wind interaction in type II-P supernovae to constrain the wind-mass loss of red supergiant stars

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arXiv 2024年

作者： Luo, Jingxiao Dessart, Luc Chen, Xuefei Liu, Zhengwei Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Institut d'Astrophysique de Paris CNRS-Sorbonne Université 98 bis boulevard Arago ParisF-75014 France

The properties of H-rich, type II-plateau supernova (SN II-P) progenitors remain uncertain, and this is primarily due to the complexities associated with red supergiant (RSG) wind-mass loss. Recent studies have suggested that the interaction of the ejecta with a standard RSG wind should produce unambiguous signatures in the optical (e.g., a broad, boxy Hα profile) and in the UV (especially Ly α and Mg ii λλ 2795, 2802) a few years following the explosion. Such features are expected to be generic in all SNe II-P and can be utilized to constrain RSG winds. Here, we investigate the possibility of detecting late-time (0.3-10 years since explosion) SNe II-P in the NUV with the China Space Station Telescope (CSST). Convolving the existing model spectra of ejecta-wind interactions in SNe II-P with the transmission functions of the CSST, we calculated the associated multiband light curves, in particular, the NUV (255 nm - 317 nm) band, as well as the NUV − r color. We find that the CSST will be able to detect the NUV radiation associated with ejecta-wind interaction for hundreds SNe II-P out to a few hundred Mpc over its ten-year main sky survey. The CSST will therefore provide a sizable sample of SNe II-P with the NUV signatures of ejecta-wind interaction. This will be helpful for understanding the mass loss history of SN II-P progenitors and their origins. © 2024, CC BY-NC-SA.

关键词： Space stations

Hemispheric prediction of solar cycles 25 and 26 from multivariate sunspot time-series data via Informer models

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Astronomical Techniques and Instruments 2025年第1期2卷 16-26页

作者： Jie Cao Tingting Xu Linhua Deng Xueliang Zhou Xinhua Zhao Nanbin Xiang Fuyu Li Miao Wan Weihong Zhou School of Mathematics and Computer Science Yunnan Minzu UniversityKunming 650504China State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Radio Science and Technology Center(πCenter) Chengdu 610041China Yunnan Observatories Chinese Academy of SciencesKunming 650216China National Laboratory on Adaptive Optics Chinese Academy of SciencesChengdu 610209China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

Solar activity plays an important role in influencing space weather,making it important to understand numerous aspects of spatial and temporal variations in the Sun's radiative ***-performance deep learning models and long-term observational records of sunspot relative numbers are essential for solar cycle *** the multivariate time series of monthly sunspot relative numbers provided by the National Astronomical Observatory of Japan and two Informer-based models,we forecast the amplitude and timing of solar cycles 25 and *** main results are as follows:(1)The maximum amplitude of solar cycle 25 is higher than the previous solar cycle 24 and the following solar cycle 26,suggesting that the long-term oscillatory variation of sunspot magnetic fields is related to the roughly centennial Gleissberg cyclicity.(2)Solar cycles 25 and 26 exhibit a pronounced Gnevyshev gap,which might be caused by two non-coincident peaks resulting from solar magnetic flux transported by meridional circulation and mid-latitude diffusion in the convection zone.(3)Hemispheric prediction of sunspot activity reveals a significant northsouth asynchrony,with activity level of the Sun being more intense in the southern *** results are consistent with expectations derived from precursor methods and dynamo theories,and further provide evidence for internal changes in solar magnetic field during the decay of the Modern Maximum.

关键词： Solar magnetic fields Solar cycle Deep learning

Irradiation-driven mass transfer for massive companion stars in supersoft X-rays sources

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arXiv 2024年

作者： Zhao, Weitao Meng, Xiangcun Cui, Yingzhen Institute of Electromagnetic Wave Henan normal university Xinxiang453007 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

Context. Supersoft X-ray sources (SSSs) have been proposed as one of the progenitors for Type Ia supernovae. However, the exact origin of the quasi-periodic variability in the optical light curve remains a mystery. Aims. In this work, our goal is to investigate the effect of the feedback of an evolved main-sequence companion star on X-ray irradiation and find whether periodic X-ray irradiation of the companion star could reproduce periodic mass transfer. Methods. Using the Modules for Experiments in Stellar Astrophysics (MESA) code, we modeled the evolutionary track of the companion star under the influence of supersoft X-ray irradiation, and we calculated the resulting mass transfer rate. Results. We find that the supersoft X-ray heating of the companion star can result in the expansion of the companion, causing it to greatly overflow its Roche lobe and thereby increasing the mass transfer rate. The periodic X-ray irradiation on the companion stars leads to periodic changes in the mass transfer rate. For a given companion star, higher irradiation efficiencies result in a higher mass transfer rate. Additionally, the mass transfer rate increases as the mass of the companion star decreases for a given irradiation efficiency. Conclusions. The companion star undergoing thermal timescale mass transfer is periodically irradiated by the X-rays from the WD, which can lead to periodic enhancement of the mass transfer rate. The mechanism could be the origin of the quasi-periodic optical light curve in supersoft X-ray sources. © 2024, CC BY.

关键词： Supernovae

An Exposure Meter of Lijiang Fiber-fed High Resolution Spectrograph

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arXiv 2024年

作者： Yu, Xiao-Guang Ji, Kai-Fan Zhang, Xi-Liang Chang, Liang Cai, Yun-Fang Qin, Ying Shang, Zhen-Hong Yunan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Faculty of Information Engineering and Automation Kunming University of Science and Technology Kunming650500 China

In 2016, an exposure meter was installed on the Lijiang Fiber-fed High-Resolution Spectrograph to monitor the coupling of starlight to the science fiber during observations. Based on it, we investigated a method to estimate the exposure flux of the CCD in real time by using the counts of the photomultiplier tubes (PMT) of the exposure meter, and developed a software to optimize the control of the exposure time. First, by using flat-field lamp observations, we determined that there is a linear and proportional relationship between the total counts of the PMT and the exposure flux of the CCD. Second, using historical observations of different spectral types, the corresponding relational conversion factors were determined and obtained separately. Third, the method was validated using actual observation data, which showed that all values of the coefficient of determination were greater than 0.92. Finally, software was developed to display the counts of the PMT and the estimated exposure flux of the CCD in real-time during the observation, providing a visual reference for optimizing the exposure time control. Copyright © 2024, The Authors. All rights reserved.

关键词： Exposure meters

A catalog of new slowly pulsating B-type stars

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arXiv 2024年

作者： Shi, Xiang-Dong Qian, Sheng-Bang Zhu, Li-Ying Li, Lin-Jia 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

This paper reports the discovery of new slowly pulsating B-type stars. Based on the photometric, spectral, and astrometric data of TESS, LAMOST, and Gaia surveys, we have found 286 new slowly pulsating B-type stars (SPB stars) and 21 candidates. Among these, 20 are Be stars or candidates with emission line profiles. It is shown that these SPB stars have luminosities between 40 and 2850 L☉ and effective temperatures ranging from 10000K to 21000K. Their pulsation periods are from 0.14 to 6.5 days with amplitude ranges of 0.2-20 mmag in TESS band. It is indicated that these targets follow the distribution of the SPB stars in the period-luminosity (P-L) and the period-temperature (P-T) diagrams. Their positions on the H-R diagram reveal that most of these pulsators are distributed in the instability region of SPB stars, in the main-sequence evolutionary stage, and with mass ranges of 2.5-7 M☉. However, there are some targets beyond the red edge of the theoretical instability region, which should be caused by the rapid rotation reducing the measured effective temperature. The discovery of these new SPB stars increases the total number by over 60%, which are significant samples for further investigating the structure and evolution of intermediate-mass and even massive stars by asteroseismology. © 2024, CC BY.

关键词： Giant stars

The fractions of post-binary-interaction stars and evolved blue straggler stars on the red giant branch of globular clusters

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Research in Astronomy and Astrophysics 2021年第9期21卷 101-110页

作者： Dan-Dan Wei Bo Wang Hai-Liang Chen Hai-Feng Wang Xiao-Bo Gong Dong-Dong Liu Deng-Kai Jiang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of ScienceKunming 650216China University of Chinese Academy of Science Beijing 100049China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China LAMOST

The red giant branch(RGB)of globular clusters(GCs)is home to some exotic stars,which may provide clues on the formation of multiple stellar populations in *** is well known that binary interactions are responsible for many exotic ***,it is important to understand what fraction of stars on the RGB of GCs is the result of binary *** this paper,we performed a binary population synthesis study to track the number of post-binary-interaction(post-BI)stars that appear on the RGB,with particular emphasis on the evolved blue straggler stars(E-BSSs).Assuming an initial binary fraction of nearly 50%,we find that about half of the objects on the RGB(called giants)underwent the binary interactions,and that E-BSSs account for around 10%of the giants in our standard *** also compare the properties of post-BI giants that evolved from different *** find that the initial orbital period and mass ratio distributions significantly affect the fraction of post-BI *** results imply that the non-standard stars from binary interactions provide a non-negligible contribution to the RGB stars in GCs,which should be considered in future investigations of the origin of multiple stellar populations.

关键词： blue stragglers stars:chemically peculiar globular clusters:general binaries:general

Determination method of binary fractions by the integrated spectrum

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arXiv 2024年

作者： Zhang, F. Li, L. Han, Z. Wang, X. Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

We need to resolve the individual stars for binary fraction determinations of stellar systems. Therefore, it is not possible to obtain the binary fractions for dense or distant stellar systems. We proposed a method to determine the binary fraction of a dense or distant stellar system. The method is to first determine the binary fraction variation for any two adjacent regions and then add up those binary fraction variations along the radial direction to obtain the binary fraction for a stellar system. Binary fraction variation is derived by using ten binary fraction-sensitive spectral absorption feature indices (SAFIs) and the binary fraction variation calibrations in terms of these SAFIs. Using this method, we first presented the binary fraction variations for twenty-one Galactic globular clusters (GCs). By comparisons, we find that they agree well with the binary fractions based on the main-sequence fiducial line method by previous studies. This verifies that the above mentioned method is feasible. Next, we presented the binary fraction variations of thirteen Galactic GCs. We gave the relationships between binary fraction and various parameters, and found that binary fraction is negatively correlated with NHB and NRR, binary fraction of some studies is not strongly correlated with NBS, and the number of GCs with large binary fraction is greater at extreme blue horizontal branch population ratio. At last, if we want to obtain more accurate binary fraction, we suggest that the spectroscopic and photometric observations are conducted at an appropriate area interval for a stellar system. © 2024, CC BY-NC-ND.

关键词： Stars

He-shell flashes on the surface of oxygen-neon white dwarfs

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Research in Astronomy and Astrophysics 2021年第2期21卷 73-81页

作者： Yunlang Guo Dongdong Liu Chengyuan Wu Bo Wang 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 Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China Physics Department and Tsinghua Center for Astrophysics(THCA) Tsinghua UniversityBeijing 100084China

Accretion induced collapse(AIC)may be responsible for the formation of some interesting neutron star binaries(e.g.,millisecond pulsars,intermediate-mass binary pulsars,etc).It has been suggested that oxygen-neon white dwarfs(ONe WDs)can increase their mass to the Chandrasekhar limit by multiple He-shell flashes,leading to AIC ***,the properties of He-shell flashes on the surface of ONe WDs are still not well *** this article,we aim to study He-shell flashes on the surface of ONe WDs in a systematic *** investigated the long-term evolution of ONe WDs accreting He-rich material with various constant mass-accretion rates by time-dependent calculations with the stellar evolution code Modules for Experiments in Stellar Astrophysics(MESA),in which the initial ONe WD masses range from 1.1 to 1.35 M_(⊙).We found that the mass-retention efficiency increases with the ONe WD mass and the mass-accretion rate,whereas both the nova cycle duration and the ignition mass decrease with the ONe WD mass and the mass-accretion *** also present the nuclear products in different accretion *** results presented in this article can be used in the future binary population synthesis studies of AIC events.

关键词： stars evolution-binaries close-supernovae general-white dwarfs

Opacity enhanced by the localization of electrons

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Science China(Physics,Mechanics & Astronomy) 2022年第3期65卷 131-131页

作者： Qian-Sheng Zhang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100012China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China

Plasmas absorbing and scattering photons are often described according to the conception of opacity. The opacity in hot, dense plasmas is crucial in many fields, including astrophysics and controlled nuclear fusion. It is a difficult problem because of many complex mechanisms involving,for instance, excited states, line broadenings, relativistic effects, and two-photon contributions. Studies on opacity.

关键词： excited instance relativistic