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681.
Based on the methods of Fisher and Watson,Fortran iv
computer programs are presented for the following analyses of directional observations on the sphere: (1) to determine if points are randomly distributed; (2) to estimate the azimuth and inclination of the center (mean direction) of a cluster and to estimate the precision (closeness) with which points are clustered; (3) to determine if two or more clusters have the same mean direction; (4) to determine if two clusters have the same precision of clustering; and (5) to locate the pole of a greatcircle girdle of points. Limitations of these analyses for undirected directional observations on the hemisphere also are given. 相似文献
682.
Correlated sixteen-second periodic bursts were observed during the flash phase of a class 2b solar flare in energetic X-rays, microwaves, and EUV ionizing radiation. The observations of the periodic structures in the various X-ray energy channels indicate that the structures are predominantly a phenomenon of high energy electrons, E>80 keV. In view of the fact that the periodic X-ray structures were correlated extensively in microwave and EUV frequencies, a plausible conclusion is that these three types of radiation have a common energy source. The acceleration of the energetic electrons must occur deep in the chromosphere where there are sufficient solar constituents that can be ionized to produce the correlated periodic EUV radiation. 相似文献
683.
684.
George W. Wetherill 《Icarus》1976,28(4):537-542
Despite the negative tone of Chapman's article, it is pointed out that there is substantial agreement between his opinions and those given in my previous publications on this subject. These areas of agreement are identified and distinguished from those which require further investigation or discussion. It is also pointed out that the apparent discrepancy between the small crater population on the Mercury intercrater terrain and the lunar plains may argue against a simultaneous late heavy bombardment. Suggested ways to resolve this discrepancy should be thoroughly evaluated. The primary need at this time is to identify further specific observational, experimental, or theoretical tests in order to advance beyond the stage of agreeing that the available evidence permits a simultaneous late heavy bombardment, to the more difficult task of determining whether or not it probably occurred. 相似文献
685.
Yoji Kondo Margherita Hack John B. Hutchings George E. McCluskey Jr. Miroslav Plavec Ronald S. Polidan 《Astrophysics and Space Science》1975,38(2):353-358
High-resolution ultraviolet spectrophotometry of the complex close binary systemβ Lyrae was performed with the Princeton Telescope Spectrometer onCopernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with the resolution of 0.2 Å (far-ultraviolet) and 0.4 Å (mid-ultraviolet). The far-ultraviolet spectrum is completely dominated by emission lines indicating existence of high temperature plasma in this binary. The spectrum ofthis object is unlike any other object observed fromCopernicus. It is believed that this high temperature plasma results from dynamic mass transfer taking place in this binary. The current results are compared with the OAO-2 Wisconsin Experiment Package observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; theCopernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole. 相似文献
686.
687.
Given an incomplete rotation curve of a spiral galaxy, various assumptions about the Galaxy beyond the last observed point are made: (A) the force falls off as 1/r
2, (B) the mass density is zero, and (C) the mass density falls off as 1/r
3. The msss distributions obtained from each of these assumptions are all well behaved, and it is impossible to choose the correct curve from considerations of the resulting mass distributions alone. The correct mass distribution in the disk system of a galaxy cannot be deduced from an incomplete rotation curve. 相似文献
688.
The effects on a close binary system of one component becoming a neutron star as a result of a supernova explosion are discussed in this paper. In the case of a Type I supernova, the system can remain bound in many cases of interest. For a Type II supernova, the system will probably be disrupted although in some cases a remnant of the companion to the supernova may remain in a bound orbit.Consequently, neutron stars formed in Type I supernova explosions may exist in close binary systems. Such systems may be strong X-ray emitters due to mass flow as suggested by Shklovsky. Photons with energies in the 1–50 MeV region should also be emitted. 相似文献
689.
George A. van Otten 《The Professional geographer》1980,32(1):63-71
In the post-World War II era the need to achieve satisfactory economies of scale has led to fever but larger farms in the Willamette Valley. Vigorous demand for farm land by the nonfarm sector has served to inflate land values. As a result, farmers have turned to leasing and renting as alternatives to land purchase. Difficulty in finding suitable land with which to enlarge farm operations has led to the use of noncontiguous fields. 相似文献
690.
Spectroheliograms taken in the CN(0, 0) violet band near 3883 Å show very small scale network and cell structures with high contrast. The bandhead itself, which is a broad feature due to overlap of several CN lines, allows the diagnostic simplicity of a continuum since motions, magnetic fields, and broadening mechanisms are unimportant. We have obtained spectroheliograms in the bandhead and center-to-limb photoelectric spectra of CN(0, 0) at Kitt Peak National Observatory. From the photoelectric spectra and a detailed analysis of the formation of the CN(0, 0) spectrum we derive a best-fit one-component upper photospheric model differing from that of the HSRA and recommend a change in solar carbon abundance from the HSRA value of logA
c = 8.55 to logA
c = 8.25. From the calibrated spectroheliograms we consider a multi-component model to account for the observed fine structure intensity variations.Staff Member, Laboratory Astrophysics Division, National Bureau of Standards.Visiting Astronomer at Kitt Peak National Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. 相似文献