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Quasi-toroidal oscillations in slowly rotating stars are examined in the framework of general relativity. The oscillation frequency to first order of the rotation rate is not a single value even for uniform rotation unlike the Newtonian…
Recent studies have thrown up a big enigma. On the one hand they point to satellite galaxies rotating faster than they should with the usual theory. On the other hand they also go against explanation of Newtonian gravity with dark matter.…
Instabilities and strong dynamical interactions between several giant planets have been proposed as a possible explanation for the surprising orbital properties of extrasolar planetary systems. In particular, dynamical instabilities would…
We investigated the orbital evolution of satellite galaxies using numerical simulations. It has been long believed that the orbit suffers circularization due to the dynamical friction from the galactic halo during orbital decay. This…
Binary systems of rapidly spinning compact objects, such as black holes or neutron stars, are prime targets for gravitational wave astronomers. The dynamics of these systems can be very complicated due to spin-orbit and spin-spin couplings.…
Recent analyses of Kepler space telescope data reveal that transiting planets with orbital periods shorter than about 2-3 days are generally observed around late-type stars with rotation periods longer than about 5-10 days. We investigate…
The rotating radio transients are sporadic pulsars which are difficult to detect through periodicity searches. By using a single-pulse search method, we can discover these sources, measure their periods, and determine timing solutions. Here…
Models of rapidly rotating massive stars at low metallicities show significantly different evolution and higher metal yields compared to non-rotating stars. We estimate the spin-down time-scale of rapid rotating non-convective stars…
The organization of the orbits of most minor bodies in the Solar system seems to follow random patterns, the result of billions of years of chaotic dynamical evolution. Much as heterogeneous orbital behaviour is ubiquitous, dynamically…
Since the formulation of the problem by Newton, and during three centuries, astronomers and mathematicians have sought to demonstrate the stability of the Solar System. Thanks to the numerical experiments of the last two decades, we know…
We present rotation periods for the solar-type primary stars in 13 close (a~< 5 AU) single-lined spectroscopic binaries with known orbital periods (P) and eccentricities (e). All binaries are members of the open clusters M35 (150Myr) and…
Astrophysical fluid bodies that orbit close to one another induce tidal distortions and flows that are subject to dissipative processes. The spin and orbital motions undergo a coupled evolution over astronomical timescales, which is…
The gravitational potentials of realistic galaxy models are in general non-integrable, in the sense that they admit orbits that do not have three independent isolating integrals of motion and are therefore chaotic. However, if chaotic…
The infall of a satellite galaxy onto a galactic disk generally brings in angular momentum that is not aligned with the axis of the disk. The main dynamical issues addressed are what fraction of the orbital angular momentum of the satellite…
We consider dark solitons and their stability in spin-orbit coupled polariton condensates. The system supports spinor solitons of two types: conventional (symmetric) dark solitons and asymmetric half-dark solitons. They demonstrate…
We find that in general relativity slow down of the pulsar rotation due to the magnetodipolar radiation is more faster for the strange star with comparison to that for the neutron star of the same mass. Comparison with astrophysical…
As a direct result of ongoing efforts to detect more exoplanetary systems, an ever-increasing number of multiple-planet systems are being announced. But how many of these systems are truly what they seem? In many cases, such systems are…
The rotation periods of the host stars of extrasolar planets have been assessed against those of the Mt. Wilson stars, open cluster stars, and evolutionary stellar models that include rotation. They appear to be normal, modulo certain…
The quest of exo-Earths has become a prominent field. In this work, we study the stability of non-coplanar planetary configurations consisting of an inclined inner terrestrial planet in mean-motion resonance with an outer giant planet. We…
A 3D-dynamical model is constructed for the study of motion in the central regions of a disk galaxy with a double nucleus. Using the results of the 2D-model, we find the regions of initial conditions in the (x,px,z,py)=EJ, (y=pz=0) phase…