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981.
In March/April 1984 eleven EXOSAT observations of Her X-1 were performed sampling a full 35 day cycle. Spectral analysis of the ME and GSPC data shows that the iron line emission is present during all phases. During the main-on state we see an iron line at 6.65 ± 0.07 keV with a FWHM of 1–2 keV and an equivalent width of 300 to 400 eV. The high resolution GSPC data indicate that the line profiles have external wings and are not simple Gaussian. We report for the first time on the detection of an iron line during the intermediate-on state with about the same parameters as the main-on state line but an equivalent width a factor of 2 larger. During the off state between main-on and intermediate-on we detected a broad iron line feature at about 6.0 keV with an equivalent width of 2 keV. We discuss the Alfven region and a hot corona at the inner region of the accretion disk as the possible sites of the line production. 相似文献
982.
We review results of correlated IR, optical and X-ray observations of GX 339-4 made from March 1981 through May 1984. In the soft X-ray state, the object does not show outstanding optical and X-ray variability. Night-to-night smooth optical variations of 0.3 magnitudes were however present during one observing run. In contrast, the hard X-ray state is characterised by strong erratic optical and X-ray fluctuations on time scales from 20 milliseconds to seconds, as well as 7 to 20 second quasi-periodic oscillations. The optical counterpart appears much redder in the IR during the hard state. Particular attention is drawn to the hard to soft X-ray transition which occured in June 1981. The shape of the IR to X-ray energy distribution is discussed. The unusual features of this black hole candidate are examined in the framework of the current theories of accretion.Based partly on observations obtained at the European Southern Observatory, La Silla, Chile. 相似文献
983.
J. P. De Greve 《Space Science Reviews》1989,50(1-2):127-139
Four different aspects related to the evolution of Algols are discussed: the occurrence of a contact phase during the mass transfer, the evolution of short period systems evolving through case A mass transfer, the influence of the mass transfer on the surface abundances of both components, and the problem of the initial parameters of Algol systems. For the latter, a search is made for conservative case B systems. UZ Cyg seems to be a good candidate for such evolution. Finally, some remarks are given on the initial values of the low mass Algol S Cancri. 相似文献
984.
R. Hanel B. Conrath D. Gautier P. Gierasch S. Kumar V. Kunde P. Lowman W. Maguire J. Pearl J. Pirraglia C. Ponnamperuma R. Samuelson 《Space Science Reviews》1977,21(2):129-157
The infrared investigation on Voyager uses two interferometers covering the spectral ranges 60–600 cm–1 (17–170 m) and 1000–7000 cm–1 (1.4–10 m), and a radiometer covering the range 8000–25 000 cm–1 (0.4–1.2 m). Two spectral resolutions (approximately 6.5 and 2.0 cm–1) are available for each of the interferometers. In the middle of the thermal channel (far infrared interferometer) the noise level is equivalent to the signal from a target at 50 K; in the middle of the reflected sunlight channel (near infrared interferometer) the noise level is equivalent to the signal from an object of albedo 0.2 at the distance of Uranus.For planets and satellites with substantial atmospheres, the data will be used to investigate cloud and gas composition (including isotopic ratios), haze scale height, atmospheric vertical thermal structure, local and planetary circulation and dynamics, and planetary energy balance. For satellites with tenuous atmospheres, data will be gathered on surface and atmospheric composition, surface temperature and thermal properties, local and global phase functions, and surface structure. For Saturn's rings, the composition and radial structure, particle size and thermal characteristics will be investigated. Comparative studies of the planets and their satellite systems will be carried out.Paris Observatory.Cornell University.Jet Propulsion Laboratory.University of Maryland. 相似文献
985.
G. K. Parks C. Gurgiolo C. S. Lin K. A. Anderson R. P. Lin F. Martel H. Réme 《Space Science Reviews》1978,22(6):765-776
This article presents some of the new and important particle features that have been detected in the energy range 1 keV to 290 keV by the ISEE-1 and -2 spacecraft near the magnetopause, bow shock, and the interplanetary space. Only examples of data from the first few orbits, when the spacecraft were on the front side, are shown.Paper presented at 13th ESLAB Symposium, Innsbruck, Austria (June 5, 1978). 相似文献
986.
P. J. Christiansen M. P. Gough G. Martelli J. J. Bloch N. Cornilleau J. Etcheto R. Gendrin C. Beghin P. Decreau D. Jones 《Space Science Reviews》1978,22(4):383-400
In this paper we describe and discuss the occurrence of natural wave emissions detected by GEOS-1 at frequencies above the electron gyrofrequency. The bulk of the data presented comes from the first six months of satellite operation and thus concerns mainly dayside phenomena. The paper is arranged as follows:After some general remarks, a classification of the wave phenomena is developed in Section 2, and experimental evidence and morphological information relevant to this classification are contained in Section 3. Section 4 includes some preliminary comments on nightside observations. The results are discussed in Section 5, where it is argued that they can be understood as manifestations of electron cyclotron harmonic (Bernstein) wave emission in a plasma parameter range which has only very recently received any theoretical examinations. This theme is further developed in a comparison paper (Ronnmark et al., 1978). 相似文献
987.
Moore R.K. Claassen J.P. Lin Y.H. 《IEEE transactions on aerospace and electronic systems》1981,(3):410-421
Spaceborne synthetic aperture radar systems are severely constrained to a narrow swath by ambiguity limitations. Here a vertically scanned-beam synthetic aperture system (SCANSAR) is proposed as a solution to this problem. The potential length of synthetic aperture must be shared between beam positions, so the along-track resolution is poorer; a direct tradeoff exists between resolution and swath width. The length of the real aperture is independently traded against the number of scanning positions. Design curves and equations are presented for spaceborne SCANSARs for altitudes between 400 and 1400 km and inner angles of incidence between 20° and 40°. When the real antenna is approximately square, it may also be used for a microwave radiometer. The combined radiometer and synthetic-aperture (RADISAR) should be useful for those applications where the poorer resolution of the radiometer is useful for some purposes, but the finer resolution of the radar is needed for others. 相似文献
988.
由于随机失谐的存在,实际叶盘通常一定程度地偏离设计值,其动力学特性通常因此而发生较大改变。以某型航空压气机高保真叶盘模型为例,采用失谐叶盘减缩建模方法,对不同阶次激励下的随机失谐叶盘响应特性进行了统计分析。研究表明:叶盘最大响应随着随机失谐值的增大呈先急剧上升后下降并趋于稳定趋势,表现"阀值"效应。此外,将失谐作为设计参数,着重研究了常见的主动失谐叶盘的响应特性,可见主动失谐叶盘相较于同等失谐程度的随机失谐叶盘具有更小的响应幅值。最后,分析了主动失谐叶盘对随机失谐的鲁棒性。 相似文献
989.
E. Hilsenrath M. R. Schoeberl A. R. Douglass P. K. Bhartia J. Barnett R. Beer J. Waters M. Gunson L. Froidevaux J. Gille P. F. Levelt 《Space Science Reviews》2006,125(1-4):417-430
Aura, the last of the large EOS observatories, was launched on July~15, 2004. Aura is designed to make comprehensive stratospheric
and tropospheric composition measurements from its four instruments, HIRDLS, MLS, OMI and TES. These four instruments work
in synergy to provide data on ozone trends, air quality and climate change. The instruments observe in the nadir and limb
and provide the best horizontal and vertical resolution ever achieved from space. After over one year in orbit the instruments
are nearly operational and providing data to the scientific community. We summarize the mission, instruments, and initial
results and give examples of how Aura will provide continuity to earlier chemistry missions. 相似文献
990.
A. Kontogeorgos P. Tsitsipis X. Moussas G. Preka-Papadema A. Hillaris C. Caroubalos C. Alissandrakis J.-L. Bougeret G. Dumas 《Space Science Reviews》2006,122(1-4):169-179
Fine structure of type IV radio solar bursts with a great variety and complexity often give much information in different
ways and enable estimation of various coronal characteristics. In this work, we expose our new method for fine structure revealing
and separation of two basic kinds of type IV fine structure, as fibers and pulsations. We also estimate frequency drift of
fibers from dynamic spectra, clean from continuous background, with a prototype method using 2-D Fourier transform and we
estimate periodicities of fibers as well as pulsations with continuous wavelet transform. Working with the last method we
found periodicities close to 3 min umbral oscillations and 5 min global solar oscillations. 相似文献