相关论文: Compact stellar objects with multiple neck optical…
We discuss ultracompact stellar objects which have multiple necks in their optical geometry. There are in fact physically reasonable equations of state for which the number of necks can be arbitrarily large. The proofs of these statements…
We discuss the construction of perfect fluid stellar objects having optical geometries with multiple necks corresponding to spatially closed unstable lightlike geodesics. We prove that there exist physically reasonable models with…
Planetary nebulae (PNe) can be roughly categorized into several broad morphological classes. The high quality images of PNe acquired in recent years, however, have revealed a wealth of fine structures that preclude simplistic models for…
High massive compact stars have been reported recently in the literature, providing strong constraints on the properties of the ultradense matter beyond the saturation nuclear density. In view of these results, the calculations of quark…
The coalescence of close binary systems with two compact objects (neutron stars and black holes) are considered to be promising sources of gravitational waves for the currently built laser interferometers. Here, I review the current…
Planetary nebulae (PNe) have diverse morphological shapes, including point-symmetric and multipolar structures. Many PNe also have complicated internal structures such as torus, lobes, knots, and ansae. A complete accounting of all the…
Compact packings are specific packings of spheres which can be seen as tilings and are good candidates to maximize the density. We show that the compact packings of the Euclidean space with two sizes of spheres are exactly those obtained by…
Since various structural components of planetary nebulae manifest themselves differently, a combination of optical, infrared, submm, and radio techniques is needed to derive a complete picture of planetary nebulae. The effects of projection…
We use the well tested StarTrack binary population synthesis code to examine the properties of the population of compact object binaries. We calculate the distribution of masses and mass ratios taking into account weights introduced by…
Current observations of double neutron stars provide us with a wealth of information that we can use to investigate their evolutionary history and the physical conditions of neutron star formation. Understanding this history and formation…
In the context of the standard model of particle physics, there is a definite upper limit to the density of stable compact stars. However, if there is a deeper layer of constituents, below that of quarks and leptons, stability may be…
We present several arguments which favor the scenario of two coexisting families of compact stars: hadronic stars and quark stars. Besides the well known hyperon puzzle of the physics of compact stars, a similar puzzle exists also when…
We show that there are strong links between certain types of asymmetrical Planetary Nebulae (PNe) and symbiotic stars. Symbiotics are binaries and several have extended optical nebulae all of which are asymmetrical and ~-40% are bipolar.…
Various solutions of the kinetic equation for the equilibrium of a gravitating sphere of uniform density with a quadratic gravitational potential and a linear dependence of gravitational force on radius are examined. New analytic solutions…
Gravitational-wave detections are enabling measurements of the rate of coalescences of binaries composed of two compact objects -- neutron stars and/or black holes. The coalescence rate of binaries containing neutron stars is further…
We consider here the structure of rotating compact objects endowed with a magnetic field in general relativity as models of pulsars. We discuss first the structure of rotating stars in the framework of Hartle taking different realistic…
We study the properties of ultra-compact spherically symmetric dark matter sector star objects, being the solution of Einstein equations with two $U(1)$-gauge fields. One of them is the ordinary Maxwell field, while the auxiliary gauge…
The generic properties of compact objects made of two different fluids of dark matter are studied in a scale invariant approach. We investigate compact objects with a core-shell structure, where the two fluids are separated, and with mixed…
Hybrid stars with extremely high central energy density in their core are natural laboratories to investigate the appearance and the properties of compactified extra dimensions with small compactification radius -- if these extra dimensions…
We investigate the physical properties of quark stars with two different equations of state in generalized hybrid metric-Palatini gravity. This theory corresponds to a bi-scalar gravitational theory in which there are two…