共查询到20条相似文献,搜索用时 68 毫秒
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《明实录》是明朝历代官修的编年体史书,篇幅巨大,其中包含天象记录达6000余条,是二十四史以外中国古代天象记录的最大来源,其中包括日月食336条、月行星掩犯2622条、流陨2248条.明后期除日月食和彗星记录外,其他类型天象记录大幅减少.天象记录的密度,正德以前平均每年38条,嘉靖以后则只有每年7条.由可以回算验证的月行星掩犯记录得到错误率4.1%,属历代最佳.错误主要是资料编纂整理过程和书籍传抄过程造成的.月亮记录显示,凌晨的观测,通常记前一日日期;掩犯恒星记录显示,官内星名与传统略有差异.若干例证说明,原始记录采用日序式纪日.只是在编纂史书时,才改用干支纪日. 相似文献
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由南北朝以前171个月掩星记录所得到的地球自转长期变化 总被引:1,自引:0,他引:1
刘次沅 《中国天文和天体物理学报》1988,(2)
应用“实际可见时间段”方法研究中国古代只有日期而无观测时刻的月掩星记录,文中讨论了这些记录的真实性及其含义,由南北朝以前的58个月掩行星和113个月掩恒星记录分别得到公元1,4,5,6世纪的地球自转参数△t和ω平均值为ω=-66.8秒/世纪~2。 相似文献
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地球自转长期变化的研究依赖于古代天象记录.近年来这方面研究取得明显进展.本文着重介绍作者由中国古代公元十世纪以前732个月掩犯记录得到的最新结果,并与其他结果进行了对比和综合分析,中国月掩犯记录填补了公元三至八世纪的资料缺环,并证实了公元五世纪前后地球自转非潮项的明显变化. 相似文献
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W.J. Baggaley 《Planetary and Space Science》1985,33(4):457-459
The dependence of the occurrence probabilities of ionosonde sporadic-E parameters f0Es and fbEs on probing frequency is analyzed for wintertime for day and night for two Southern Hemisphere stations. The ionosonde data indicate that significant changes have taken place over the period 1958–1983 suggesting that Es has become increasingly dense and also less patchy. 相似文献
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The neighbouring lines a 6 D5/2 – x 6 Po 3/2 (1272.617 Å) and a 6 D5/2 – w 2 Po 3/2 (1272.657 Å) have been observed in the UV spectrum of χ Lupi to be of comparable intensity. The latter, Δ S = 2, transition would be expected to be very weak. The two upper states should display negligible mixing. We give a detailed, quantitative discussion of how the two upper states are in fact strongly mixed through their mixing with 3d6 (3 D)4p 4 Po 3/2 , and hence we explain the relative strengths of the two UV lines. 相似文献
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J.F. Noxon 《Planetary and Space Science》1982,30(6):545-557
Aircraft measurements of emission made over a 10-yr period provide information on the variation of ozone with latitude and season in the altitude region 50–90 km. Between 50 and 70 km there appears to be little variation (< ± 25%) whereas the abundance between 80 and 90 km exhibits a large seasonal change north of 30°N and much less at lower latitude. At mid and high latitude the column abundance above ~ 80 km changes from ? 1 × 1014 cm?2 in summer to about 3 × 1014 cm?2 in winter. There are occasional enhancements in both the day and twilight airglow which almost always occur in association with auroral activity or, at least, where such activity is statistically most likely. These enhancements appear to reflect a corresponding increase in the ozone mixing ratio in the upper stratosphere. While the gradient in ozone mixing ratio with latitude is generally small at altitudes between 50 and 90km there are occasions when a temporary latitude structure can be seen, particularly above 80 km. 相似文献
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Low and mid-latitude lower E-region electron temperature profiles which were obtained by means of an insitu probe were collected. Profiles which are discussed here cover the heights of 90–120 km and measurement reliability at these heights is discussed mainly in terms of electrode contamination and aerodynamical heating.Although measurement errors might exist in some of the electron temperature profiles, it is conclusively described that daytime electron temperature is very often much higher than the possible neutral temperature and Te ≈ Tn is rarely seen. 相似文献
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Asgeir Brekke 《Planetary and Space Science》1973,21(4):698-702
In a recent paper, Brekke and Pettersen (1972) have introduced a method for estimating any indirect process in the production of the ) atoms in pulsating aurora; for 38 per cent of their data they found that the decay time for the indirect mechanism was shorter than the effective lifetime of the state. These data are related to the energy transfer from the N2(A3Σ) molecules to the state, and evidence is found for this process to contribute in the altitude range below 125 km. 相似文献
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Analysis of observed spectrograms is based on comparison with synthetic spectra. The O2(b1Σ+g?X3Σ?g Atm. (1,1) band in high latitude auroras observed from the ground is found to be the strongest in the Δv = 0 sequence. It is enhanced with altitude relative to the N2 1P(2, 0)and N+2 M(2,0) bands, but the O2 Atm. (2, 2) band has an unexpected low intensity. The range of rotational temperatures of the O2 Atm. bands varies from approx. 200 to above 500 K which indicates that the altitude of the centroid of the emission region varies from about 100 km to the F-region. The highest temperature is found in the midday aurora associated with the magnetospheric cusp. Conspicuous relative variations between the intensities of N2 and O2 spectra are documented, but a satisfactory explanation of the variety is not given. Deviations of the observed O2 Atm. band intensities from the vibrational intensity distribution predicted by Franck-Condor factors indicate that the excitation of the O2 Atm. bands in aurora is not mainly due to particle impact on O2, and the contribution due to energy transfer from hot O(1D) atoms has to be found in future research. 相似文献
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Urmas Haud 《Astrophysics and Space Science》1984,104(2):337-345
It is shown that the rise of rotation velocities in the outer regions of our Galaxy may be illusive, and is caused by an excessive simplification of the methods of processing the observational data. Taking into consideration the possibility of the radial motions of the gas, we demonstrate that the existing observational data do not conflict with the hypothesis of the flat rotation curve of our Galaxy. The bending of the outer regions of the galactic disk has no significant effect on the observed radial velocities of the gaseous complexes. It is also shown that the wavy form of the rotation curve may be evoked by the spiral density waves in the Galaxy. 相似文献
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Marta Ruiz-Bermejo César Menor-Salván Susana Osuna-Esteban Sabino Veintemillas-Verdaguer 《Icarus》2008,198(1):232-241
Tholins are complex organic materials produced by irradiation of several carbon and nitrogen rich atmospheres. They could have played a key role in the origin of life on Earth because their ability to release important bioorganics, which are nowadays present in proteins, nucleic-acid bases and other important biostructures. Usually, the yield of these compounds is higher after acid hydrolysis, however little is known about the structure and chemical composition of the tholins. In this work, we propose the use of different spectroscopic and separation techniques, which are not usually applied in this field, in order to obtain complete information about the tholin structure and behavior. Two different simulation experiments of prebiotic synthesis were carried out in CH4/N2/H2 atmosphere out from spark discharge activation of aqueous aerosols and liquid water, respectively. In both cases, a hydrophilic tholin and a hydrophobic tholin were obtained. Herein, we report the application of this methodology to our hydrophilic tholins and we review, briefly, some astrobiological aspects related to these complex substances. 相似文献