分类： 天文学 >> 天文学 提交时间： 2023-02-19
Di-Fu. Guo
Kai Li
1 Fen Liu
Huai-Zhen Li Qi-Qi Xia
Xing Gao
Xiang Gao
Xu Chen
Dong-Yang Gao
Guo-You Sun
摘要： Photometric observations for the totally eclipsing binary system TYC 4002-2628-1, were obtained between November 2020 and November 2021. To determine the stellar atmospheric parameters, a spectral image was taken with the 2.16 m telescope at National Astronomical Observatory of China (NAOC). TYC 4002-2628-1 is a low-amplitude (about 0.15 mag for $V$ band), short-period (0.3670495 d), contact eclipsing binary with a total secondary eclipse. Intrinsic light curve variations and the reversal of the O'Connell effect are detected in the light curves, which may be due to spot activity. Based on the photometric solutions derived from the multi-band time series light curves, TYC 4002-2628-1 is an extremely low mass ratio contact binary with a mass ratio of $q\sim$ 0.0482 and a fill-out factor of $f\sim5\%$. By analyzing the $O-C$ variations, we find that its orbital period remains unchanged when BJD < 2458321 . Then the orbital period changed suddenly around BJD 2458743 and has an increasing rate of $dP/dt=1.62\times{10^{-5}}day\cdot yr^{-1}=140$ $second\cdot century^{-1}$ . If confirmed, TYC 4002-2628-1 would be the contact binary with the highest orbital period increasing rate so far. By investigating the ratio of orbital angular momentum to the spin angular momentum ( $J_{orb}$/$J_{spin}$ $<3$) , the instability mass ratio ($q_{inst}/q=1.84$) and the instability separation ($A_{inst}/A=1.35$), TYC 4002-2628-1 can be regarded as a merger candidate.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： High precision CCD observations of six totally eclipsing contact binaries were presented and analyzed. It is found that only one target is an A-type contact binary (V429 Cam), while the others are W-type contact ones. By analyzing the times of light minima, we discovered that two of them exhibit secular period increase while three manifest long-term period decrease. For V1033 Her, a cyclic variation superimposed on the long-term increase was discovered. By comparing the Gaia distances with those calculated by the absolute parameters of 173 contact binaries, we found that Gaia distance can be applied to estimate absolute parameters for most contact binaries. The absolute parameters of our six targets were estimated by using their Gaia distances. The evolutionary status of contact binaries was studied, we found that the A- and W- subtype contact binaries may have different formation channels. The relationship between the spectroscopic and photometric mass ratios for 101 contact binaries was presented. It is discovered that the photometric mass ratios are in good agreement with the spectroscopic ones for almost all the totally eclipsing systems, which is corresponding to the results derived by Pribulla et al. and Terrell & Wilson.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Di-Fu. Guo
Kai Li
1 Fen Liu
Huai-Zhen Li Qi-Qi Xia
Xing Gao
Xiang Gao
Xu Chen
Dong-Yang Gao
Guo-You Sun
摘要： Photometric observations for the totally eclipsing binary system TYC 4002-2628-1, were obtained between November 2020 and November 2021. To determine the stellar atmospheric parameters, a spectral image was taken with the 2.16 m telescope at National Astronomical Observatory of China (NAOC). TYC 4002-2628-1 is a low-amplitude (about 0.15 mag for $V$ band), short-period (0.3670495 d), contact eclipsing binary with a total secondary eclipse. Intrinsic light curve variations and the reversal of the O'Connell effect are detected in the light curves, which may be due to spot activity. Based on the photometric solutions derived from the multi-band time series light curves, TYC 4002-2628-1 is an extremely low mass ratio contact binary with a mass ratio of $q\sim$ 0.0482 and a fill-out factor of $f\sim5\%$. By analyzing the $O-C$ variations, we find that its orbital period remains unchanged when BJD < 2458321 . Then the orbital period changed suddenly around BJD 2458743 and has an increasing rate of $dP/dt=1.62\times{10^{-5}}day\cdot yr^{-1}=140$ $second\cdot century^{-1}$ . If confirmed, TYC 4002-2628-1 would be the contact binary with the highest orbital period increasing rate so far. By investigating the ratio of orbital angular momentum to the spin angular momentum ( $J_{orb}$/$J_{spin}$ $<3$) , the instability mass ratio ($q_{inst}/q=1.84$) and the instability separation ($A_{inst}/A=1.35$), TYC 4002-2628-1 can be regarded as a merger candidate.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We present a novel, easy-to-use method based on the photon-mapping technique to simulate photometric images of moving targets. Realistic images can be created in two passes: photon tracing and image rendering. The nature of light sources, tracking mode of the telescope, point spread function (PSF), and specifications of the CCD are taken into account in the imaging process. Photometric images in a variety of observation scenarios can be generated flexibly. We compared the simulated images with the observed ones. The residuals between them are negligible, and the correlation coefficients between them are high, with a median of $0.9379_{-0.0201}^{+0.0125}$ for 1020 pairs of images, which means a high fidelity and similarity. The method is versatile and can be used to plan future photometry of moving targets, interpret existing observations, and provide test images for image processing algorithms.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Blazar PG 1553+113 is thought to be a host of supermassive black hole binary (SMBHB) system. A 2.2-year quasi-periodicity in the $\gamma$-ray light curve was detected, possibly result of jet precession. Motivated by the previous studies based on the $\gamma$-ray data, we analyzed the X-ray light curve and spectra observed during 2012--2020. The 2.2-year quasi-periodicity might be consistent with the main-flare recurrence in the X-ray light curve. When a weak rebrightening in the $\gamma$-ray was observed, a corresponding relatively strong brightening in the X-ray light curve can be identified. The "harder-when-brighter" tendency in both X-ray main and weak flares was shown, as well as a weak "softer-when-brighter" behavior for the quiescent state. We explore the possibility that the variability in the X-ray band can be interpreted with two-jet precession scenario. Using the relation between jets and accretion discs, we derive the primary black hole mass $\simeq 3.47\times 10^8M_{\odot}$ and mass of the secondary one $\simeq 1.40\times 10^8M_{\odot}$, and their mass ratio $\sim 0.41$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The cut-off mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 ($q\sim0.055$ for J082700, and $q\sim0.089$ for J132829). J082700 is a shallow contact binary with a contact degree of $\sim$19%, and J132829 is a deep contact system with a fillout factor of $\sim$70%. The $O-C$ diagram analysis indicated that both the two systems manifest long-term period decrease. In addition, J082700 exhibits a cyclic modulation which is more likely resulted from Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of $q\lesssim0.1$ and discovered that the values of $J_{spin}/J_{orb}$ of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One is that some physical processes, unknown to date, are not considered when Hut presented the dynamically instability criterion. The other is that the dimensionless gyration radius ($k$) should be smaller than the value we used ($k^2=0.06$). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The photometric and spectroscopic investigations of ten contact binaries were presented for the first time. It is discovered that the mass ratios of all the ten targets are smaller than 0.15, they are extremely low mass ratio contact binaries. Seven of them are deep contact binaries, two are medium contact binaries, while only one is a shallow contact system. Five of them show O'Connell effect, and a dark spot on one of the two components can lead to a good fit of the asymmetric light curves. The orbital period studies of the ten binaries reveal that they all exhibit long-term period changes, six of them are increasing, while the others are shrinking. The LAMOST spectra were analyzed by the spectral subtraction method, and all the ten targets exhibit excess emissions in the H$_\alpha$ line, indicating chromospheric activity. The evolutionary states of the two components of the ten binaries were studied, and it is found that their evolutionary states are identical to those of the other contact binaries. Based on the study of the relation between orbital angular momentum and total mass, we discovered the ten systems may be at the late evolutionary stage of a contact binary. The initial masses of the two components and the ages of them were obtained. By calculating the instability parameters, we found that the ten contact binaries are relatively stable at present.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Research into OJ 287 has been ongoing for many years. In 2020 April-June, this source underwent the second highest X-ray outburst (second only to the 2016-2017 outburst) and the mechanism of this outburst is still under debate. In this paper, we discuss two scenarios to explore the origin of the outburst: an after-effect of a black hole-disc impact and a tidal disruption event (TDE). We present the weak correlations of the spectral index versus X-ray flux and the hardness ratio (HR) versus the soft X-ray flux during the outburst, and these features are different from the case in the quiescent state. The correlations are compared with those of the 2016-2017 outburst with the highest X-ray flux in monitoring history. Analysis of the outbursts in 2016-2017 and 2020 shows that the expected time of the X-ray outburst, based on the theory of the after-effect of the black hole-disc impact and the estimation of available data, is inconsistent with historical observations. The soft X-ray spectra, the barely temporal evolution of colour, and the evolution of the HR mean that the 2020 outburst shares similar features with the 2016-2017 outburst, which was considered as a possible candidate for a TDE. Additionally, we find that the predictions of full TDEs ($t^{-5/3}$) and partial TDEs ($t^{-9/4}$) for the soft X-ray decay light curve are well fitted. Our analysis suggests that the 2020 outburst in OJ 287 is probably related to the TDE candidate.
分类： 心理学 >> 实验心理学 提交时间： 2017-10-13
Ning Yang
Ye He
Zhe Zhang
Hao-Ming Dong
Lei Zhang
Xing-Ting Zhu
Xiao-Hui Hou
Yin-Shan Wang
Quan Zhou
Zhu-QingGong
Li-Zhi Cao
Ping Wang
Yi-Wen Zhang
Dan-Yang Sui
TingXu1
Gao-Xia Wei
Zhi Yang
Lili Jiang
Hui-Jie Li
Ting-YongFeng
摘要： Abstract: To face the challenges of keeping healthy in increasing population sizes of both ageing and developing people in China, a fundamental request from the public health is the development of lifespan normative trajectories of brain and behavior. This paper introduces the Chinese Color Nest Project (CCNP 2013–2022), a large-scale tenyear program of modeling brain and behavioral trajectories for human lifespan (6–85 years old). We plan to gradually collect the behavioral and brain imaging data at ages across the lifespan on nationwide and depict the normal trajectory of Chinese brain development across the lifespan, based on the accelerated longitudinal design in the coming next 10 years starting at 2013. Various psychiatric disorders have been demonstrated highly relevant to abnormal events during the neurodevelopment regarding their onset ages of first episodes. Therefore, delineation of normative growth curves of brain and cognition in typically developing children is extremely useful for monitoring, early detecting and intervention of various neurodevelopmental disorders. In this paper, we detailed the developing part of CCNP, devCCNP. It tracked 192 healthy children and adolescents (6–18 years old) in Beibei district of Chongqing for the first 5 years of the full CCNP cohort (2013–2017). To demonstrate the feasibility of implementing the longterm follow-up of CCNP, we here comprehensively document devCCNP in terms of its experimental design, sample strategies, data acquisition and storage as well as some preliminary results and data sharing roadmap for future. Specifically, we first describe the accelerated longitudinal sampling design as well as its exact ratio of sample dropping off during the data collection. Second, we present several initial findings such as canonical growth curves of cortical surface areas of a set of well-established large-scale functional networks of the human brain. Finally, together with records generated by many psychological and behavioral tests, we will provide an individual growing-up report for each family participating the program, initiating the potential guidance on the individual academic and social development. The resources introduced in the current work can provide first-hand data for a series of coming Chinese brain development studies, such as Chinese Standard MRI Brain Templates, Normative Growth Curves of Chinese Brain and Cognition as well as Mapping of Language Areas in Chinese Developing Brain. These would not only offer normative references of the atypical brain and cognition development for Chinese population but also serve as a strong force on accelerating the pace of integrating Chinese brain development into the national brain program or Chinese Brain Project.
分类： 物理学 >> 核物理学 提交时间： 2016-08-31
Ying Zhang
Jing Huang
Ding Chen
Liu-Ming Zhai
Xu Chen
Xiao-Bin Hu
Yu-Hui Lin
Hong-Bo Jin
Xue-Yao Zhang
Cun-Feng Feng: Huan-Yu Jia
Xun-Xiu Zhou
DANZENGLUOBU
Tian-Lu Chen
LABACIREN
Mao-Yuan Liu
Qi Gao
ZHAXICIREN
摘要： A new hybrid experiment has been constructed to measure the chemical composition of cosmic rays around the "knee" in the wide energy range by the Tibet ASγ collaboration at Tibet, China, since 2014. They consist of a high-energy air-shower-core array (YAC-II), a high-density air-shower array (Tibet-III) and a large underground water-Cherenkov muon-detector array (MD). In order to obtain the primary proton, helium and iron spectra and their "knee" positions in the energy range lower than 1016 eV, each of PMTs equipped to the MD cell is required to measure the number of photons capable of covering a wide dynamic range of 100 - 106 photoelectrons (PEs) according to Monte Carlo simulations. In this paper, we firstly compare the characteristic features between R5912-PMT made by Japan Hamamatsu and CR365-PMT made by Beijing Hamamatsu. This is the first comparison between R5912-PMT and CR365-PMT. If there exists no serious difference, we will then add two 8-inch-in-diameter PMTs to meet our requirements in each MD cell, which are responsible for the range of 100 - 10000 PEs and 2000 - 1000000 PEs, respectively. That is, MD cell is expected to be able to measure the number of muons over 6 orders of magnitude.
分类： 物理学 >> 核物理学 提交时间： 2016-08-31
摘要： A new air-shower core-detector array (YAC : Yangbajing Air-shower Core-detector array) has been developed to measure the primary cosmic-ray composition at the "knee" energies in Tibet, China, focusing mainly on the light components. The prototype experiment (YAC-I) consisting of 16 detectors has been constructed and operated at Yangbajing (4300 m a.s.l.) in Tibet since May 2009. YAC-I is installed in the Tibet-III AS array and operates together. In this paper, we performed a Monte Carlo simulation to check the sensitivity of YAC-I+Tibet-III array to the cosmic-ray light component of cosmic rays around the knee energies, taking account of the observation conditions of actual YAC-I+Tibet-III array. The selection of light component from others was made by use of an artificial neural network (ANN). The simulation shows that the light-component spectrum estimated by our methods can well reproduce the input ones within 10\% error, and there will be about 30\% systematic errors mostly induced by the primary and interaction models used. It is found that the full-scale YAC and the Tibet-III array is powerful to study the cosmic-ray composition, in particular, to obtain the energy spectra of protons and helium nuclei around the knee energies.
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