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浏览/检索结果: 共17条，第1-10条 帮助

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Photometric study of semi-detached eclipsing binary TW Cas based on TESS photometry 期刊论文  OAI收割
NEW ASTRONOMY, 2022, 卷号: 93
作者:  Ma WW(马文武);  Zhao EG(赵二刚);  Sarotsakulchai, Thawicharat
  |  收藏  |  浏览/下载：37/0  |  提交时间：2022/07/18
Synchronous X-ray/Optical QPOs from the Black Hole LMXB MAXI J1820+070 期刊论文  OAI收割
Monthly Notices of the Royal Astronomical Society, 2021
作者:  HXMT
  |  收藏  |  浏览/下载：53/0  |  提交时间：2022/02/08
black hole physics  Low Mass X-ray Binaries  accretion  accretion  discs  stars: individual (MAXI J1820+070)  Astrophysics - High Energy  Astrophysical Phenomena  Abstract: We present high-speed optical photometry from SAAO and SALT on the black hole LMXB MAXI J1820+070 (ASSASN-18ey), some of it simultaneous with NICER, Swift and Insight-HXMT X-ray coverage. We detect optical Quasi-Periodic Oscillations (QPOs) that move to higher frequencies as the outburst progresses, tracking both the frequency and evolution of similar X-ray QPOs previously reported. Correlated X-ray/optical data reveal a complex pattern of lags, including an anti-correlation and a sub-second lag that evolve over the first few weeks of outburst. They also show correlated components separated by a lag equal to the QPO period roughly centered on zero lag, implying that the inter-band variability is strongly and consistently affected by these QPOs at a constant phase lag of roughly ±Ю The synchronisation of X-ray and optical QPOs indicates that they must be produced in regions physically very close to each other  we thus propose that they can be explained by a precessing jet model, based on analogies with V404 Cyg and MAXI J1348-630.  
Geochronology, geochemistry and metallogenic dynamics of gold-polymetallic deposits in Xicha region, the northeastern margin of the North-China Platform 期刊论文  OAI收割
ACTA PETROLOGICA SINICA, 2020, 卷号: 36, 期号: 4, 页码: 1127-1150
作者:  Qian Ye;  Sun JinLei;  Li YuJin;  Yu Na;  Liu JinLong
  |  收藏  |  浏览/下载：24/0  |  提交时间：2021/02/02
Geochronology, geochemistry and metallogenic dynamics of gold-polymetallic deposits in Xicha region, the northeastern margin of the North-China Platform 期刊论文  OAI收割
ACTA PETROLOGICA SINICA, 2020, 卷号: 36, 期号: 4, 页码: 1127-1150
作者:  Qian Ye;  Sun JinLei;  Li YuJin;  Yu Na;  Liu JinLong
  |  收藏  |  浏览/下载：14/0  |  提交时间：2021/02/02
An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文  OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者:  HXMT
  |  收藏  |  浏览/下载：61/0  |  提交时间：2022/02/08
accretion  accretion disks  black hole physics  X-rays: binaries  time  Astrophysics - High Energy Astrophysical Phenomena  Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.  
Evolution of permafrost in China during the last 20 ka 期刊论文  OAI收割
Science China Earth Sciences, 2019, 卷号: 62, 期号: 8, 页码: 1207-1223
作者:  Huijun JIN;  Xiaoying JIN;  Ruixia HE;  Dongliang LUO;  Xiaoli CHANG;  Shaoling WANG;  Sergey S MARCHENKO;  Sizhong YANG;  Chaolu YI;  Shijie LI;  Stuart A HARRIS
  |  收藏  |  浏览/下载：31/0  |  提交时间：2020/05/07
Asteroseismology of the Double-mode High-amplitude delta Scuti Star VX Hydrae 期刊论文  OAI收割
ASTROPHYSICAL JOURNAL, 2018, 卷号: 861, 期号: 2, 页码: 96
作者:  Yan, HL;  Xue, HF;  Fu, JN;  Fox-Machado, L;  Shi, JR
  |  收藏  |  浏览/下载：81/0  |  提交时间：2018/12/27
WZ Sge: An eclipsing cataclysmic variable evolving towards the period minimum 期刊论文  OAI收割
NEW ASTRONOMY, 2017, 卷号: 56, 页码: 22-27
作者:  Han ZT(韩忠涛);  Qian SB(钱声帮);  Voloshina, Irina;  Zhu LY(朱俐颖);  Han, Z. -T.(Chinese Acad Sci, Yunnan Observ, POB 110, Kunming 650216, Peoples R China)
收藏  |  浏览/下载：19/0  |  提交时间：2017/08/29
Study on distribution of long-period stacking ordered phase in Mg-Gd-Y-Zn-Zr alloy using friction stir processing 期刊论文  OAI收割
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 2015, 卷号: 626, 页码: 275-285
Q.; Xiao Yang, B. L.; Wang, D.; Zheng, M. Y.; Ma, Z. Y.
收藏  |  浏览/下载：30/0  |  提交时间：2015/05/08
Formation of long-period stacking ordered phase only within grains in Mg-Gd-Y-Zn-Zr casting by friction stir processing 期刊论文  OAI收割
Journal of Alloys and Compounds, 2013, 卷号: 581, 页码: 585-589
Q. Yang; B. L. Xiao; D. Wang; M. Y. Zheng; K. Wu; Z. Y. Ma
收藏  |  浏览/下载：22/0  |  提交时间：2013/12/24