共查询到20条相似文献，搜索用时 15 毫秒
1.
The subject of this paper is to derive the solution of generalized fractional kinetic equations. The results are obtained
in a compact form containing the Mittag-Leffler function, which naturally occurs whenever one is dealing with fractional integral
equations. The results derived in this paper provide an extension of a result given by Haubold and Mathai in a recent paper
(Haubold and Mathai, 2000).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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用云台１ｍ望远镜镜卡焦（缩焦）ＣＣＤ测光系统对测光标准星进行了ＢＶＲＩ四色测光,计算得到了该系统的转换方程及其转换结果,并对计算结果进行了分析讨论． 相似文献
5.
DION BRANDT WOLF UWE REMOLD ALAN J. FRANZSEN CHRISTIAN KOEBERL LUTZ WENDORFF 《Meteoritics & planetary science》1998,33(3):447-453
Abstract— New gravity and magnetic data were obtained along ground profiles across the Roter Kamm impact crater in the southern Namib desert of Namibia. As the traverses of previous studies did not extend sufficiently beyond the crater rim, it had not been possible to adequately determine the regional background values. The gravity results of this study are similar to those obtained by Fudali in 1973, in that a negative, near-symmetrical anomaly was obtained over the crater center. This anomaly conforms to the results expected for a sediment and impact breccia-filled, simple bowl-shaped crater. The magnetic results of this study, however, are different to those previously reported, which is most probably as a result of the longer profiles used in this new study. A slight positive magnetic anomaly was obtained over the crater interior. Short-wavelength, high-amplitude anomalies observed in the vicinity of the crater rim reflect magnetization contrasts that are probably related to brecciation and block rotation. Modelling of the positive magnetic anomaly indicates the possibility of a small magnetic body or lining at the crater floor-breccia interface in the interior of the crater. Also presented is a 10 m contour digital elevation model of the crater and its environs. 相似文献
6.
R. Trampedach 《Astrophysics and Space Science》2010,328(1-2):213-219
7.
Simon F. Portegies Zwart Koji Takahashi 《Celestial Mechanics and Dynamical Astronomy》1999,73(1-4):179-186
Recent N-body simulations have shown that there is a serious discrepancy between the results of N-body simulations and the
results of Fokker-Planck simulations for the evolution of globular and rich open clusters under the influence of the galactic
tidal field. In some cases, the lifetime obtained from Fokker-Planck calculations is more than an order of magnitude smaller
than those from N-body simulations. In this paper we show that the principal cause for this discrepancy is an over-simplified
treatment of the tidal field used in previous Fokker-Planck simulations. We performed new Fokker-Planck calculations using
a more appropriate implementation for the boundary condition of the tidal field. The implementation is only possible with
anisotropic Fokker-Planck models, while all previous Fokker-Planck calculations rely on the assumption of isotropy. Our new
Fokker-Planck results agree well with N-body results. Comparison of the two types of simulations gives a better understanding
of the evolution of such clusters.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
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
9.
A. Morbidelli M. Gounelle H. F. Levison W. F. Bottke 《Meteoritics & planetary science》2006,41(6):874-887
Abstract— 1996 FG3 is a binary near‐Earth object (NEO) that was likely formed during a tidal disruption event. Our results indicate that the formation of this binary object was unlikely to have occurred when the progenitor had a encounter velocity with the Earth significantly smaller than its current value (10.7 km/s); The formation of the binary object on an orbit similar to the present one is possible, and the survival of the satellite constrains this to have happened less than 1.6 Ma ago. However, the binary object could also have been formed when the progenitor's encounter velocity with Earth was >12 km/s, and in this case we cannot constrain its formation age. Our results indicate that tidal disruptions occurring among NEOs with low velocity encounters with Earth are unlikely to produce long‐lasting NEO binaries. Thus, tidal disruption may not be able to completely re‐supply the observed population. This would imply that a significant fraction of the observed NEO binaries evolved out of the main asteroid belt. Overall, our results suggest to us that the CM2 meteorites having cosmic ray exposure (CRE) ages of ?200,000 yr were likely liberated by the tidal disruption of a primitive NEO with a relative velocity with the Earth significantly smaller than that of 1996 FG3. We propose a list of such objects, although as far as we know, none of the candidates is a binary for the reasons described above. 相似文献
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11.
Joseph D. Gelfand 《Astrophysics and Space Science》2007,308(1-4):39-42
On 27 December 2004, just the third giant flare was observed from a magnetar, in this case SGR 1806-20. This giant flare was
the most energetic of the three, and analysis of a Very Large Array observation of SGR 1806-20 after the giant flare revealed
the existence of a new, bright, transient radio source at its position. Follow-up radio observations of this source determined
that initially, this source underwent a mildly relativistic one-sided expansion which ceased at the same time as a temporary
rebrightening of the radio source. These observational results imply that the radio emission is powered by ∼1024 g of baryonic material which was ejected off the surface on the neutron star during the giant flare.
相似文献
12.
In this paper we show that a change in the signs of some of the metric components of the solution of the field equations for
the classical cosmic string results in a solution which we interpret as a time-dependent wall composed of tachyons. We show
that the walls have the property of focusing the paths of particles which pass through them. As an illustration of this focusing,
we demonstrate the results of a simple simulation of the interaction between one such tachyon wall and a rotating disk of
point masses. This interaction leads to the temporary formation of spiral structures. These spiral structures exist for a
time on the order of one galactic rotation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
In order to study the dynamical behaviour of asteroids in commensurability with a planet, we propose a phase diagram obtained
by short computer time. We test this numerical procedure by analyzing the behaviour of real and fictitious asteroids in first
order commensurabilities with Jupiter. We have also studied the evolution time of the orbital elements and other variables
to compare these results with those obtained in the phase diagram. The results obtained with our numerical technique were
compared to similar results previously obtained by other authors.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Rudolf Dvorak 《Celestial Mechanics and Dynamical Astronomy》1997,68(1):63-73
We report on the different results concerning the stability of the hierarchical triple systems where a close binary is accompanied
by a third star. There are different possible approaches to answer the question of the stability limits for such triple stars:
the most direct investigations can be undertaken in integrating numerically the respective equations of motion for many different
initial conditions. It is then difficult to take into account all the important parameters like eccentricities, inclination,
phases and masses. Analytical approaches and qualitative methods are more approriate to deal with this problem; the respective
results confirm the numerically found results that:
1. for prograde orbits the ratio semimajor axis of the inner orbits to the periastron position of the outer orbit is approximately
3.2
2. for retrograde orbits this ratio is just some 10 percents smaller
3. the results are not sensitive in what concerns the masses involved
4. There is a tendency that the inclinations and eccentricities change slightly the stability limits mentioned above.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
In this paper,we propose a long short-term memory(LSTM)deep learning model to deal with the smoothed monthly sunspot number(SSN),aiming to address the problem whereby the prediction results of the existing sunspot prediction methods are not uniform and have large deviations.Our method optimizes the number of hidden nodes and batch sizes of the LSTM network structures to 19 and 20,respectively.The best length of time series and the value of the timesteps were then determined for the network training,and one-step and multi-step predictions for Cycle 22 to Cycle 24 were made using the well-established network.The results showed that the maximum root-mean-square error(RMSE)of the one-step prediction model was6.12 and the minimum was only 2.45.The maximum amplitude prediction error of the multi-step prediction was 17.2%and the minimum was only 3.0%.Finally,the next solar cycles(Cycle 25)peak amplitude was predicted to occur around 2023,with a peak value of about 114.3.The accuracy of this prediction method is better than that of the other commonly used methods,and the method has high applicability. 相似文献
16.
The Fermi LAT provides a continuous and uniform monitoring of the Universe in the gamma-ray band. During the first year many gamma-ray blazar flares, some unidentified transients and emission by the Sun while in a quiet state were promptly detected. This is mainly due to the design of the mission, featuring a detector, the LAT with a wide field of view, and to the operation of the spacecraft itself, that can cover every region of the sky every 3 hours. Nevertheless, the scientific exploitation of this monitoring is more fruitful when early information about transients reaches a broader community. In this respect, the indefatigable activity of flare advocates, who worked on weekly shifts to validate the results and quickly broadcast information about flares and new detections, was the key to most scientific results. 相似文献
17.
In May 2002, the solar chromosphere was observed with a two‐dimensional spectrometer which is mounted in the German Vacuum Tower Telescope (VTT) at the Observatorio del Teide/Tenerife. The aim of this observation was to investigate the fine structure of the solar chromosphere seen in Hα. We took narrow‐band filtergrams (Δλ ≈ 72 mÅ) by scanning through this line. Broad‐band images taken strictly simultaneously with the narrow‐band filtergrams were restored by speckle methods. The instantaneous optical transfer function from this restoration procedure was used for the reconstruction of the narrow‐band images. Some results of this high spatial resolution observation are presented below. 相似文献
18.
In this paper a unique 2.3–4.2 GHz radio spectrum of the flare impulsive phase, showing fast positively drifting bursts superimposed on a slowly negatively drifting burst, is presented. Analyzing this radio spectrum it was found that the flare started somewhere near the transition region, where upward propagating MHD waves were generated during the whole impulsive phase. Moreover, it was found that behind a front of these ascending MHD waves the downward propagating electron beams, which bombarded dense layers of the solar atmosphere, were accelerated. It seems that, simultaneously with the increase of beam bombardment intensity, the intensity of MHD waves was increasing and thus the MHD shock wave generation and the electron beam acceleration and bombardment formed a self-consistently amplifying flare process. At higher coronal heights this process was followed by a type II radio burst, i.e. by the MHD flare shock. To verify this concept, the numerical modeling of the shock-wave generation and propagation in space from a flare site near the transition region up to 3 solar radii was made. Comparing the thermal and magnetic field disturbances, it was found that those of magnetic origin are more relevant in this case. Combining the results of interpretation and numerical simulation, a model of the February 27, 1992 flare is suggested and new aspects of this model are discussed. 相似文献
19.
A. Giunta E. Bozzo F. Bernardini G. Israel L. Stella M. Falanga S. Campana A. Bazzano A. J. Dean M. Mendez 《Monthly notices of the Royal Astronomical Society》2009,399(2):744-749
IGR J18483−0311 was discovered with INTEGRAL in 2003 and later classified as a supergiant fast X-ray transient. It was observed in outburst many times, but its quiescent state is still poorly known. Here, we present the results of XMM–Newton , Swift and Chandra observations of IGR J18483−0311. These data improved the X-ray position of the source, and provided new information on the timing and spectral properties of IGR J18483−0311 in quiescence. We report the detection of pulsations in the quiescent X-ray emission of this source, and give for the first time a measurement of the spin-period derivative of this source. In IGR J18483−0311, the measured spin-period derivative of −(1.3 ± 0.3) × 10−9 s s−1 likely results from light travel time effects in the binary. We compare the most recent observational results of IGR J18483−0311 and SAX J1818.6−1703, the two supergiant fast X-ray transients for which a similar orbital period has been measured. 相似文献
20.
P. Zlobec 《Solar physics》1975,43(2):453-461
A constant polarization degree was found in groups of type I bursts having intermediate polarization for all the duration of the group. The same circumstance was verified also for analogous bursts present during a type IV event. The consequences of this behaviour, considering also the results of some recent papers, is discussed. The polarization amount is probably intrinsic to the source itself. 相似文献