共查询到20条相似文献，搜索用时 93 毫秒
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一般认为，Langmuir波转换为电磁波是太阳射电Ⅲ型暴的重要机制，由电子束流不稳定性可以很容易的激发Langrnuir波。正向Langmuir波和反向Langmuir波的相互作用被认为是产生静电的高次谐波的原因之一。本文对于含有温度的双流不稳定性的方程进行了解析求解，发现了温度和柬流速度分别对于K〉0时Langmuir波色散关系具有显著的影响，进而采用了粒子模拟的方法，进一步证实了解析推导的结果。 相似文献
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本文用完全动力学程式计算了Ⅰ型超新星爆发。这些模型是依据氦或碳和氧构成星核,部分地或全部地产生瞬时完成的核燃烧。计算中将动力学方程、核统计平衡、Rayleigh-Taylor不稳定性等物理过程联合起来求解。重点比较了Rayleigh-Taylor不稳定性的影响,现不能作出完全肯定的结论。计算结果列在表1、表2和图2—6中。 相似文献
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韩韬 《紫金山天文台台刊》1994,(4)
在本文中我们得到了慢速运动中两个球对称非旋转天体在辐射作用力影响下的运动方程。此方程相对论改正达到了(v/c)~2、(v/c)~4、(v/c)~5量级。运动方程只依赖于相对论质量,而与天体的内部结构和致密度无直接关系。这意味着运动方程可以应用于象中子星和黑洞一类具有强内引力的天体。 相似文献
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本文介绍对分光仪PSP0探测器TH7832 CCD的评估结果。该CCD系统工作在-130℃～-110℃温度下,具有较好的稳定性和很好的线性。系统的读出噪声约为300电子,动态范围3500。在实验结果的基础上,文章对系统性能的改善进行了简单的讨论。 相似文献
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本文介绍对分光仪ＰＳＰ０探测器ＴＨ７８３２ＣＣＤ的评估结果。该ＣＣＤ系统工作在－１３０℃￣－１１０℃温度下,具有较好的稳定性和很好的线性。系统的读出噪声约为３００电子,动态范围３５００。在实验结果的基础上,文章对系统性能的改善进行了简单的讨论。 相似文献
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本文利用Thomson CCD,在北京天文台兴隆站施密特望远镜上进行BVRI四色测光,得到了该测光系统的颜色转换方程,并对所得结果进行了分析探讨。同时论证了BAO-CCD系统在施密特望远镜上用于测光的可行性。 相似文献
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Priscilla A. Sousa Silva Maisa O. Terra 《Celestial Mechanics and Dynamical Astronomy》2012,113(2):141-168
The present contribution investigates the applicability of the associated initial condition sets generated by the algorithmic definition of the weak stability boundary in the lunar sphere of influence in the context of Earth-to-Moon low-energy capture transfers. First, we test the applicability of the initial condition sets in view of two mission strategies, namely, direct inner transfers in the Planar Circular Restricted Three-Body Problem and external transfers based in the Patched Three-Body approach. Then, we check the consistency of the stability classification regarding the selection of captured solutions, identifying the stable subsets which provide temporary capture solutions. Additionally, we show the diversity of behaviors classified as stable by the current stability criteria of the algorithmic definition, which indicates that the algorithmic criteria must be reviewed in order to guarantee that the stable solutions correspond solely to low-energy capture orbits. The combination of our analyses allows the detection of the subsets of stable initial conditions that provide feasible Earth-to-Moon transfer solutions. Specifically, we show an external low-energy Earth- to-Moon transfer with zero midcourse correction at the patching section. 相似文献
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Zoltán Makó 《Celestial Mechanics and Dynamical Astronomy》2014,120(3):233-248
This paper provides a study on the connection between Hill stability and weak stability in the framework of the spatial elliptic restricted three-body problem. We determine a necessary condition for weak stability by giving an upper and a lower bound of qualitative measure of the Hill stability. The sufficient condition for weak stability and the symmetry of weak stable regions around the planets of the Solar System is also investigated. 相似文献
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It is shown that a sufficient condition for the stability of an incompressible sheared gravitationally stratified ideal magnetofluid with flow-aligned horizontal magnetic field is that there exists a Galilean frame in which the flow is nowhere super-Alfvénic (similarly, stability is assured in a compressible shear flow without gravity if there exists a frame in which the flow nowhere exceeds the cusp speed). Complex eigenvalue bounds are presented for unstable flows. The stability condition is applied to the solar tachocline; it suggests that any shear instabilities associated with radial gradients in flow speed should be stabilized by fields of above about 7 kG. 相似文献
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N. Falcón 《Astrophysics and Space Science》1997,256(1-2):399-402
The plasma thermal stability condition under convection is discutided. Using Cattaneo law and mixing length theory before relaxation lets show a new thermal stability condition for plasmas in astrophysics. Application in neutron stars and low mass x-ray binaries stars is mentioned. 相似文献
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Noboru Takeichi 《Celestial Mechanics and Dynamical Astronomy》2010,108(4):405-416
The parametric excitation of a gravity gradient stabilized spacecraft induced by the periodic solar pressure torque is discussed.
The solar pressure torque in the linearized equations of motion appears as linear terms with periodic coefficients. The attitude
stability is analyzed numerically through the calculation of the Floquet multiplier. The perturbation method is also applied
to identify the instability condition analytically. It is made clear that the periodic solar pressure torque can destabilize
the coupled roll and yaw attitude motion of the spacecraft. It is also shown that the conditions of parametric resonance are
included in the gravity gradient stability condition. Nonlinear simulations are also carried out to verify the effect of the
parametric resonance. The numerical simulation using actual parameters shows that the spacecraft inevitably experiences a
large amplitude attitude motion due to the periodic solar pressure torque even if the gravity gradient stability condition
is satisfied. 相似文献
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Resonant orbits in the vicinity of asteroid 216 Kleopatra 总被引：3，自引：0，他引：3
This investigation examines the resonant orbits in the vicinity of asteroid 216 Kleopatra using a precise gravitational model, with emphasis on their crucial role in determining the global orbital behaviors. Three-dimensional Monte Carlo simulations of test particle trajectories are launched to find the condition and probability distribution of resonance. It is revealed the resonant orbits are rich and concentrated in the near-field regime, which provides a short-term mechanism to clear the vicinal ejecta away from the asteroid. The unstable boundary predicted in our calculations is consistent with the observed mutual orbits of satellites S/2008 (216) 1 and S/2008 (216) 2. The probability distribution of resonance is considered as an indicator of the stability of vicinal orbits, and the results are identical to the previous analysis by Scheeres et al. (Icarus 121:67, 1996) for the stability of retrograde orbits around asteroid 4769 Castalia. 相似文献
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A necessary and sufficient condition for the ideal magnetohydrodynamic stability of 2D current sheet models of prominences suspended in a potential coronal field with line-tying is developed using the energy method. This condition takes the form of two simple coupled second-order differential equations which may be integrated along a field line to find marginal stability. The two conditions (85) and (86) of Anzer (1969) are now only sufficient for stability. Two current sheet models are investigated and it is shown that for a potential coronal field allowing perturbed electric currents to flow, line-tying can completely stabilize the equilibria for realistic heights. 相似文献
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The comparative analysis of dense stellar models governed by quadratic and linear equations of state
《New Astronomy》2021
In the present article we construct physically viable models of anisotropic charged compact stellar objects admitting quadratic equation of state and linear equation of state. We analyze the physical behavior of compact star models 4U1538-52, LMCX-4, and Vela X-1 with in the frame work of general relativity. Our stellar models are free from singularities, satisfy all energy conditions and exhibit physically admissible characters. The necessary stability criteria viz. Buchdhal condition, adiabatic index and causality condition all stand true for our charged anisotropic compact stellar models. We also inspect the physical characteristics of compact stars via Linear equation of state by applying slight changes in the parameters of the models pertaining to Quadratic equation of state and analyze the models in the perspective of both equations of state. We study the physical attributes of the model 4U1538-52 extensively by implementing analytical and graphical tools. The models retain their validity for both linear as well as quadratic equations of state, however there is a slight variation in few attributes of the models. 相似文献
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The ideal MHD stability of the 2D twisted magnetic flux tube prominence model of Cartledge and Hood (1993) is investigated. The model includes a temperature profile that varies from realistic prominence values up to typical coronal values. The prominence is considered to be of finite-width and finite height. The stability properties of the prominence models are studied by using a method that generates a separate necessary condition and a sufficient condition. These conditions give bounds on the parameters that define marginal stability. In many cases these bounds are quite close so that further, more detailed, stability calculations are not necessary. A number of parameter regimes are examined, corresponding to different profiles of the prominence temperatures, densities, and magnetic field shear. It is found that the model admits realistic stable and unstable loop lengths for observed prominence parameters when the axial magnetic field component does not vanish. 相似文献
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Klaus Jockers 《Solar physics》1968,3(4):603-610
The stability of the solar wind is studied in the case of spherical symmetry and constant temperature. It is shown that the stability problem must be formulated as a mixed initial and boundary-value problem in which are prescribed the perturbation values of velocity and density at an initial time and additionally the velocity perturbation at the base of the corona for all times. The solution is constructed by linear superposition of normal solutions, which contain the time only in an exponential factor. The stability problem becomes a singular eigenvalue problem for the amplitudes of the velocity and pressure perturbations, since additionally to the boundary condition at the base of the corona one must add the condition that the amplitudes behave regularly at the critical point. It is proved that only stable eigenvalues exist. 相似文献