A source of high-velocity white dwarfs     

Melvyn B. Davies  rew King  Hans Ritter 《Monthly notices of the Royal Astronomical Society》2002,333(2):463-468

We investigate whether the recently observed population of high-velocity white dwarfs can be derived from a population of binaries residing initially within the thin disc of the Galaxy. In particular, we consider binaries where the primary is sufficiently massive to explode as a Type II supernova. A large fraction of such binaries are broken up when the primary then explodes as a supernova, owing to the combined effects of the mass loss from the primary and the kick received by the neutron star on its formation. For binaries where the primary evolves to fill its Roche lobe, mass transfer from the primary leads to the onset of a common envelope phase during which the secondary and the core of the primary spiral together as the envelope is ejected. Such binaries are the progenitors of X-ray binaries if they are not broken up when the primary explodes. For those systems that are broken up, a large number of the secondaries receive kick velocities ∼100–200 km s⁻¹ and subsequently evolve into white dwarfs. We compute trajectories within the Galactic potential for this population of stars and relate the birth rate of these stars over the entire Galaxy to those seen locally with high velocities relative to the local standard of rest (LSR) . We show that for a reasonable set of assumptions concerning the Galactic supernova rate and the binary population, our model produces a local number density of high-velocity white dwarfs compatible with that inferred from observations. We therefore propose that a population of white dwarfs originating in the thin disc may make a significant contribution to the observed population of high-velocity white dwarfs.  相似文献   

The origin of the rebrightening in soft X-ray transient outbursts     

M. R. Truss  G. A. Wynn  J. R. Murray  A. R. King 《Monthly notices of the Royal Astronomical Society》2002,337(4):1329-1339

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Strong triple interactions in the general three-body problem     

Joanna P. Anosova 《Celestial Mechanics and Dynamical Astronomy》1991,51(1):1-15

Strong three-body interactions play a decisive role in the course of the dynamical evolution of triple systems having positive as well as negative total energies. These interactions may produce qualitative changes in the relative motions of the components. In triple systems with positive or zero total energies the processes of formation, disruption or exchange of the components of binaries take place as the result of close approaches of the three single bodies or as the result of the passages of single bodies past wide or hard binaries. In the triple systems with negative energies, the strong triple interactions may result in an escape from the system as well as a formation of a hard final binary. This paper summarizes the general results of the studies of the strong three-body interactions in the triple systems with positive and negative energies. These studies were conducted at the Leningrad University Observatory by computer simulations during 1968–1989.  相似文献   

An Explicit Symplectic Integrator for Cometary Orbits     

Vacheslav Emel'yanenko 《Celestial Mechanics and Dynamical Astronomy》2002,84(4):331-341

A new symplectic algorithm is developed for cometary orbit integrations. The integrator can handle both high-eccentricity orbits and close encounters with planets. The method is based on time transformations for Hamiltonians separated into Keplerian and perturbation parts. The adaptive time-step of this algorithm depends on the distance from a centre and the magnitude of perturbations. The explicit leapfrog technique is simple and efficient.  相似文献   

Stokes imaging, Doppler mapping and Roche tomography of the AM Herculis system V834 Cen   总被引：1，自引：0，他引：1  

Stephen B. Potter  E. Romero-Colmenero  C. A. Watson  D. A. H. Buckley  A. Phillips 《Monthly notices of the Royal Astronomical Society》2004,348(1):316-324

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Analysis of photoelectric light curves of V448 CYG taking the Roche geometry into account     

M. I. Kumsiashvili  N. T. Kochiashvili  G. Djurasevi 《Astrophysics》2005,48(1):44-52

Three-color photoelectric UBV light curves of the close binary system V448 Cyg obtained at the Abastumani Astrophysical Observatory are analyzed using a new code by Djurasevi. A new value for the ratio of the masses of the components, which is the fundamental parameter for determining the absolute elements of the system, has recently been published. The parameters obtained in our analysis differ substantially from those published previously because the new mass ratio has been employed. The location of the components of V448 Cyg on a mass-logg plot shows that this system, similarly to XZ Cep and V382 Cyg, is in a phase subsequent to a rapid transfer of mass.Translated from Astrofizika, Vol. 48, No. 1, pp. 59–68 (February 2005).  相似文献   

Erratum: Orbital parameters of infalling dark matter substructures     

A. J. Benson 《Monthly notices of the Royal Astronomical Society》2005,364(3):1104-1104

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The bicoherence as a diagnostic for models of high-frequency quasi-periodic oscillations   总被引：1，自引：0，他引：1  

Thomas J. Maccarone  Jeremy D. Schnittman 《Monthly notices of the Royal Astronomical Society》2005,357(1):12-16

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XMM–Newton observations of UW CrB: detection of X-ray bursts and evidence for accretion disc evolution     

Pasi Hakala  Gavin Ramsay  Panu Muhli  Phil Charles  Diana Hannikainen  Koji Mukai  Osmi Vilhu 《Monthly notices of the Royal Astronomical Society》2005,356(3):1133-1138

UW CrB (MS 1603+2600) is a peculiar short-period X-ray binary that exhibits extraordinary optical behaviour. The shape of the optical light curve of the system changes drastically from night to night, without any changes in overall brightness. Here we report X-ray observations of UW CrB obtained with XMM–Newton . We find evidence for several X-ray bursts, confirming a neutron star primary. This considerably strengthens the case that UW CrB is an accretion disc corona system located at a distance of at least 5–7 kpc (3–5 kpc above the Galactic plane). The X-ray and Optical Monitor (ultraviolet–optical) light curves show remarkable shape variation from one observing run to another, which we suggest are due to large-scale variations in the accretion disc shape resulting from a warp that periodically obscures the optical and soft X-ray emission. This is also supported by the changes in phase-resolved X-ray spectra.  相似文献   

An Observational Study of Contact Binaries with Large Temperature Differences Between Components     

Michał Siwak 《Astrophysics and Space Science》2005,296(1-4):289-292

In this paper we investigate a sample of contact eclipsing binary systems, which exhibit a large temperature difference (at least 1000 K) between the components. Considering the effective temperature of the primary star, the systems were divided into three groups. We applied a Monte Carlo method as a more suitable procedure for the search of the system configurations previously known as contact binaries with a large temperature difference and with a negligible value of the filling factor. Using only data presented in the literature, we found that the geometrical configuration of almost all systems from the second group is near-contact rather than contact.  相似文献