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G.Handler A. A.Pamyatnykh W.Zima D. J.Sullivan N.Audard A.Nitta 《Monthly notices of the Royal Astronomical Society》1998,295(2):377-385
We present 132 h of new time-series photometric observations of the δ Scuti star CD−24 7599 acquired during 86 nights from 1993 to 1996 to study its frequency and amplitude variations. By using all published observations we demonstrate that the three dominating pulsation modes of the star can change their photometric amplitudes within one month at certain times, while the amplitudes can remain constant within the measurement errors at other times. CD−24 7599 also exhibits frequency variations, which do not show any correspondence between the different modes. The typical time-scale for the amplitude variations is found to be several hundred days, which is of the same order of magnitude as the inverse linear growth rates of a selected model. We find no evidence for periodic amplitude modulation of two of the investigated modes ( f 2 and f 3 ), but f 1 may exhibit periodic modulation. The latter result could be spurious and requires confirmation. The observed frequency variations may either be continuous or reflect sudden frequency jumps. No evidence for cyclical period changes is obtained. We exclude precession of the pulsation axis and oblique pulsation for the amplitude variations. Beating of closely spaced frequencies cannot explain the amplitude modulations of two of the modes, while it is possible for the third. Evolutionary effects, binarity, magnetic field changes or avoided crossings cannot be made responsible for the observed period changes. Only resonance between different modes may be able to explain the observations. However, at this stage a quantitative comparison is not possible. More observations, especially data leading to a definite mode identification and further measurements of the temporal behaviour of the amplitudes and frequencies of CD−24 7599, are required. 相似文献
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Voronova O. S. Zima A. L. Kladov V. L. Cherepanova E. V. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(9):1042-1052
Izvestiya, Atmospheric and Oceanic Physics - The results of satellite wildfire monitoring and estimates for the amounts of emissions of harmful gases and fine aerosols in Siberia from 2001 to 2019... 相似文献
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闪电哨声波作为探索空间物理环境的重要媒介,淹没在海量的电磁卫星数据中.近年来随着计算机视觉和深度学习等人工智能技术的发展,从电磁卫星的存档数据中自动检测闪电哨声波的算法取得了一定的效果.本文对近年来闪电哨声波智能检测算法的文献进行了整理和总结.首先,阐述闪电哨声波在电磁卫星数据中呈现的时频特征和类型;然后,介绍了闪电哨声波智能检测算法的流程并从闪电哨声波的特征提取、分类和定位三个方面对主要的智能检测算法进行归纳、总结和评述;其次,简述了闪电哨声波智能检测模型的评价指标;接着,在张衡一号(ZH-1)卫星的磁场数据上对三种典型的闪电哨声波智能检测算法进行复现,并对三种算法的优缺点进行了较深入的分析;最后,对基于电磁卫星的闪电哨声波智能检测的研究领域进行总结和展望. 相似文献
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Doklady Earth Sciences - The multiannual variability of wildfire areas and volumes of emissions of carbon components (CO, CO2) and aerosol (PM2.5) caused by wildfires has been analyzed for the... 相似文献
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Bondur V. G. Voronova O. S. Gordo K. A. Zima A. L. Feoktistova N. V. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(9):1029-1041
Izvestiya, Atmospheric and Oceanic Physics - The results of wildfire satellite monitoring and estimates of the volumes of related emissions of CO and CO2 carbon-bearing trace gases and PM2.5 fine... 相似文献
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Bondur V. G. Voronova O. S. Cherepanova E. V. Tsidilina M. N. Zima A. L. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(12):1457-1469
Izvestiya, Atmospheric and Oceanic Physics - An analysis is performed of the annual and intraseasonal dynamics of wildfire areas and volumes of trace gas components (CO, CO2, CH4, NO, and NO2) and... 相似文献
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M. Desmet M. Briquet † A. Thoul ‡ W. Zima P. De Cat G. Handler I. Ilyin E. Kambe J. Krzesinski H. Lehmann S. Masuda P. Mathias D. E. Mkrtichian J. Telting K. Uytterhoeven S. L. S. Yang C. Aerts 《Monthly notices of the Royal Astronomical Society》2009,396(3):1460-1472
We present the results of a spectroscopic multisite campaign for the β Cephei star 12 (DD) Lacertae. Our study is based on more than thousand high-resolution high S/N spectra gathered with eight different telescopes in a time span of 11 months. In addition, we make use of numerous archival spectroscopic measurements. We confirm 10 independent frequencies recently discovered from photometry, as well as harmonics and combination frequencies. In particular, the slowly pulsating B-stars (SPB)-like g -mode with frequency 0.3428 d−1 reported before is detected in our spectroscopy. We identify the four main modes as (ℓ1 , m 1 ) = (1, 1), (ℓ2 , m 2 ) = (0, 0), (ℓ3 , m 3 ) = (1, 0) and (ℓ4 , m 4 ) = (2, 1) for f 1 = 5.178 964 d−1 , f 2 = 5.334 224 d−1 , f 3 = 5.066 316 d−1 and f 4 = 5.490 133 d−1 , respectively. Our seismic modelling shows that f 2 is likely the radial first overtone and that the core overshooting parameter αov is lower than 0.4 local pressure scale heights. 相似文献
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