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991.
We review results about protoplanetary disk models, protoplanet migration and formation of giant planets with migrating cores.
We first model the protoplanetary nebula as an α–accretion disk and present steady state calculations for different values
of α and gas accretion rate through the disk. We then review the current theories of protoplanet migration in the context
of these models, focusing on the gaseous disk–protoplanet tidal interaction. According to these theories, the migration timescale
may be shorter than the planetary formation timescale. Therefore we investigate planet formation in the context of a migrating
core, considering both the growth of the core and the build–up of the envelope in the course of the migration.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
992.
Y. Terada M. Ishida K. Mukai T. Dotani K. Makishima S. Naik T. Hayashi S. Okada R. Nakamura T. Enoto 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(3):512-517
Although rotating neutron stars (NSs) have been regarded as being textbook examples of astrophysical particle acceleration sites for decades, details of the acceleration mechanism remain a mystery; for example, we cannot yet observationally distinguish “polar cap” models from “outer gap” models. To solve the model degeneracy, it is useful to study similar systems with much different physical parameters. Strongly magnetized white dwarfs (WDs) are ideal for this purpose, because they have essentially the same system geometry as NSs, but differ largely from NSs in the system parameters, including the size, magnetic field, and the rotation velocity, with the induced electric field expected to reach 1013–1014 eV. Based on this idea, the best candidate among WDs, AE Aquarii, was observed with the fifth Japaneses X-ray satellite, Suzaku. The hard X-ray detector (HXD) on-board Suzaku has the highest sensitivity in the hard X-ray band over 10 keV. A marginal detection in the hard X-ray band was achieved with the HXD, and was separated from the thermal emission. The flux corresponds to about 0.02% of its spin-down energy. If the signal is real, this observation must be a first case of the detection of non-thermal emission from WDs. 相似文献
993.
纵向尾流间隔计算方法研究 总被引:1,自引:0,他引:1
综合考虑了飞机的速度、翼展、机翼面积、发动机推力等参数,应用空气动力学中的环量计算理论、尾流消散原理等,将动量定理和涡阻力的计算原理应用到尾流间隔的计算,分别建立了纵向尾流间隔计算模型。采用实际数据计算验证模型的正确性。 相似文献
994.
Chengming Tan Yihua Yan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(6):992-997
We have investigated the source characteristic and coronal magnetic field structure of six impulsive solar energetic particle (SEP) events selected from Wang et al. [Wang, Y.-M., Pick, M., Mason, G.M. Coronal holes, jets, and the origin of 3He-rich particle events. ApJ 639, 495, 2006] and Pick et al. [Pick, M., Mason, G.M., Wang, Y.-M., Tan, C., Wang, L. Solar source regions for 3He-rich solar energetic particle events identified using imaging radio, optical, and energetic particle observations. ApJ 648, 1247, 2006]. Some results are obtained: first, 2 events are associated with wide (≈100°) CMEs (hereafter wide CME events), another 4 events are associated with narrow (?40°) CMEs (hereafter narrow CME events); second, the coronal magnetic field configuration of narrow CME events appear more simple than that of the wide CME events; third, the photospheric magnetic field evolutions of all these events show new emergence of fluxes, while one case also shows magnetic flux cancellation; fourth, the EUV jets usually occurred very close to the footpoint of the magnetic field loop, while meter type III bursts occurred near or at the top of the loop and higher than EUV jets. Furthermore, the heights of type III bursts are estimated from the result of the coronal magnetic field extrapolations. 相似文献
995.
New methods of local helioseismology and uninterrupted time series of solar oscillation data from the Solar and Heliospheric
Observatory (SOHO) have led to a major advance in our understanding of the structure and dynamics of active regions in the
subsurface layers. The initial results show that large active regions are formed by repeated magnetic flux emergence from
the deep interior, and that their roots are at least 50 Mm deep. The active regions change the temperature structure and flow
dynamics of the upper convection zone, forming large circulation cells of converging flows. The helioseismic observations
also indicate that the processes of magnetic energy release, flares and coronal mass ejections, might be associated with strong
(1–2 km/s) shearing flows, 4–6 Mm below the surface. 相似文献
996.
L.H. Deng Z.Q. Qu T. Liu W.J. Huang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
We investigate the north–south (N–S) asynchrony of the polar faculae and compare it with the hemispheric asynchrony of solar activity at low latitudes. We find that, (1) both the solar activity at high and low latitudes do not synchronously occur in the northern and southern hemispheres, there is phase shifts between the two hemispheres; (2) the N–S asynchrony of the polar faculae is a function of latitudes, implying that the asynchrony of the polar faculae between the two hemispheres is related to the hemispheric asymmetry and latitudinal distribution of the polar faculae. 相似文献
997.
998.
S. Parenti J.-C. VialP. Lemaire 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(1):144-147
In this paper, we summarize the work done to build a UV-EUV spectral atlas of a prominence and we introduce some recent scientific results obtained from these data. 相似文献
999.
Jorge Casares Phil Charles 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2731-2736
The determination of fundamental parameters in X-ray luminous (persistent) X-ray binaries has been classically hampered by the large optical luminosity of the accretion disc. New methods, based on irradiation of the donor star and burst oscillations, provide the opportunity to derive dynamical information and mass constraints in many persistent systems for the first time. These techniques are here reviewed and the latest results presented. 相似文献
1000.
Jean-Marie Hameury Jean-Pierre Lasota 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2857-2861
Outer radius variations play an important role in the disc structure and evolution. We consider theoretical and observational consequences of such variations in cataclysmic binaries and low-mass X-ray binaries. We find that the action of tidal torques must be important well inside the tidal radius. We also conclude that it is doubtful that the tidal–thermal instability is responsible for the superoutburst/superhump phenomena. 相似文献