Gravitational wave detection through microlensing?   总被引：1，自引：0，他引：1  

Roberto Ragazzoni  Gianpaolo Valente  Enrico Marchetti 《Monthly notices of the Royal Astronomical Society》2003,345(1):100-110

It is shown that accurate photometric observations of a relatively high-magnification microlensing event  ( A ≫ 1)  , occurring close to the line of sight of a gravitational wave (GW) source, represented by a binary star, can allow the detection of subtle gravitational effects. After reviewing the physical nature of such effects, it is discussed to what extent these phenomena can actually be caused by GWs. Expressions for the amplitude of the phenomena and the detection probability are supplied.  相似文献   

The physics of pulses in gamma-ray bursts: emission processes, temporal profiles and time-lags     

Frédéric Daigne  Robert Mochkovitch 《Monthly notices of the Royal Astronomical Society》2003,342(2):587-592

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HD 82943行星系统的2:1共振与稳定性     

季江徽  刘林 《天文学报》2005,46(3):282-293

用直接数值积分方法通过模拟不同的行星构型探讨了HD82943行星系统(由两颗共振的巨行星组成)的长期动力演化,同时,还研究了在相空间的轨道运动.在对系统长达107年数值积分中,发现所有的稳定轨道均与2:1共振相关联.典型地,在相同的时标内,两个共振幅角θ1和θ2同时(或其中之一)存在秤动.由于共振幅角在一定范围内的秤动,因而使两颗行星轨道半长径被约束而表现为规则运动模式.另外,利用分析模型(包含了外行星偏心率e2的因素),还讨论了对于不同取值的e2和相对近星点经度θ时,内行星在相空间的运动,并发现2:1轨道共振对于相对较小的e2以及当θ=0°时易于保持.此外,适中的e2将导致系统的两颗行星进入深度共振状态.再者,分析模型和数值计算的结果吻合得很好,两者都揭示了行星系统的2:1共振结构.  相似文献   

Gravitational wave radiation from the coalescence of white dwarfs     

P. Lorén-Aguilar  J. Guerrero  J. Isern  J. A. Lobo  E. García-Berro 《Monthly notices of the Royal Astronomical Society》2005,356(2):627-636

We compute the emission of gravitational radiation from the merging of a close white dwarf binary system. This is done for a wide range of masses and compositions of the white dwarfs, ranging from mergers involving two He white dwarfs, through mergers in which two CO white dwarfs coalesce, to mergers in which a massive ONe white dwarf is involved. In doing so we follow the evolution of the binary system using a smoothed particle hydrodynamics code. Even though the coalescence process of the white dwarfs involves considerable masses, moving at relatively high velocities with a high degree of asymmetry we find that the signature of the merger is not very strong. In fact, the most prominent feature of the coalescence is that in a relatively small time-scale (of the order of the period of the last stable orbit, typically a few minutes) the sources stop emitting gravitational waves. We also discuss the possible implications of our calculations for the detection of the coalescence within the framework of future space-borne interferometers like LISA.  相似文献   

The kinematics of the large western knot in the halo of the young planetary nebula NGC 6543     

Deborah L. Mitchell  M. Bryce  J. Meaburn  J. A. López  M. P. Redman  D. Harman  M. G. Richer  H. Riesgo 《Monthly notices of the Royal Astronomical Society》2005,362(4):1286-1294

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Simulation of a population of isolated neutron stars evolving through the emission of gravitational waves     

C. Palomba 《Monthly notices of the Royal Astronomical Society》2005,359(3):1150-1164

We study, via a Monte Carlo simulation, a population of isolated asymmetric neutron stars where the magnitude of the magnetic field is low enough so that the dynamical evolution is dominated by the emission of gravitational waves. A starting population, with age uniformly distributed back to 100 Myr (or 500 Myr) and endowed with a birth kick velocity, is evolved in the Galactic gravitational potential to the present time. In describing the initial spatial distribution, the Gould belt, with an enhanced neutron star formation rate, is taken into account. Different models for the initial period distribution are considered. The star ellipticity, measuring the amount of deformation, is drawn from an exponential distribution. We estimate the detectability of the emitted gravitational signals by the first and planned second generation of interferometric detectors. Results are parametrized by the fraction of the whole galactic neutron star population made up of these kinds of sources. Some possible mechanisms, which would make possible the existence of such a population, are discussed. A comparison of the gravitational spin-down with the braking due to a possible interaction of the neutron star with the interstellar medium is also presented.  相似文献   

The range of effects of azimuthal isotropy and EDA anisotropy in sedimentary basins   总被引：4，自引：0，他引：4  

Philip Wild  Stuart Crampin 《Geophysical Journal International》1991,107(3):513-529

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Nature of microstructure in pulsar radio emission     

G. Machabeli  D. Khechinashvili  G. Melikidze  D. Shapakidze 《Monthly notices of the Royal Astronomical Society》2001,327(3):984-988

We present a model for microstructure in pulsar radio emission. We propose that micropulses result from alteration of the radio wave generation region by nearly transverse drift waves propagating across the pulsar magnetic field and encircling the bundle of the open magnetic field lines. It is demonstrated that such waves can modify the curvature of the field lines significantly. This, in turn, affects strongly fulfilment of the resonance conditions necessary for the excitation of radio waves. The time-scale of micropulses is therefore determined by the wavelength of the drift waves. The main features of the microstructure are naturally explained within the framework of this model.  相似文献   

Final tidal evolution of orbit-orbit resonances     

Th. Pauwels 《Celestial Mechanics and Dynamical Astronomy》1994,59(2):101-127

In this paper we describe a model for the tidal evolution of an orbit-orbit resonance between two satellites of the same planet. We let the system evolve till infinity or until the resonance is destroyed. We find that there are asymptotic values for the eccentricities and inclinations. We list the possible final stages that a resonance can achieve, we give a few examples, and finally we discuss the limitations of the model and its possible applications to real systems.  相似文献   

Classification of planetary nebulae by their departure from axisymmetry     

NoamSoker  RonHadar† 《Monthly notices of the Royal Astronomical Society》2002,331(3):731-735

We propose a scheme to classify planetary nebulae (PNe) according to their departure from axisymmetric structure. We consider only departure along and near the equatorial plane, i.e. between the two sides perpendicular to the symmetry axis of the nebula. We consider six types of departure from axisymmetry: (1) PNe where the central star is not at the centre of the nebula; (2) PNe having one side brighter than the other; (3) PNe having unequal size or shape of the two sides; (4) PNe where the symmetry axis is bent, e.g. the two lobes in a bipolar PN are bent toward the same side; (5) PNe where the main departure from axisymmetry is in the outer regions, e.g. an outer arc; and (6) PNe that show no departure from axisymmetry, i.e. any departure, if it exists, is on scales smaller than the scale of blobs, filaments and other irregularities in the nebula. PNe that possess more than one type of departure are classified by the most prominent type. We discuss the connection between departure types and the physical mechanisms that may cause them, mainly resulting from the influence of a stellar binary companion. We find that ∼50 per cent of all PNe in the analysed sample possess large-scale departure from axisymmetry. This number is larger than that expected from the influence of binary companions, namely ∼25–30 per cent. We argue that this discrepancy comes from many PNe where the departure from axisymmetry, mainly unequal size, shape or intensity, results from the presence of long-lived and large (hot or cool) spots on the surface of their asymptotic giant branch progenitors. Such spots locally enhance the mass-loss rate, leading to a departure from axisymmetry, mainly near the equator, in the descendent PN.  相似文献