Related papers: Do "isolated" planetary mass objects orbit mirror …
In this paper we consider the possibility that strange quark matter may be manifested in the form of strangelet crystal planets. These planet-like objects are made up of nuggets of strange quark matter (SQM), organized in a crystalline…
There is much debate on how high-mass star formation varies with environment, and whether the sparsest star-forming environments are capable of forming massive stars. To address this issue, we have observed eight apparently isolated OB…
Planet formation is often considered in the context of one circumstellar disk around one star. Yet stellar binary systems are ubiquitous, and thus a substantial fraction of all potential planets must form and evolve in more complex,…
The understanding of the origin of dark matter has great importance for cosmology and particle physics. Several interesting extensions of the standard model dealing with solution of this problem motivate the concept of hidden sectors…
We argue that pulsars may be spin-polarized neutron stars, i.e. cosmic permanent magnets. This would simply explain several observational facts about pulsars, including the 'beacon effect' itself i.e. the static/stable misalignment of…
The $\ddot P$ (Backer 1992, Backer et al. 1993, Thorsett et al. 1993) observed for PSR~B1620-26 in the globular cluster M4 is most likely due to external gravitational jerk from a bound companion. Solving for the $\ddot P$ observed,…
The extreme conditions found near black holes and neutron stars provide a unique opportunity for testing physical theories. Observations of both types of compact objects can be used to probe regions of strong gravity, allowing for tests of…
The basic geometry of the Solar System -- the shapes, spacings, and orientations of the planetary orbits -- has long been a subject of fascination as well as inspiration for planet formation theories. For exoplanetary systems, those same…
Dense stellar environments as hosts of ongoing star formation increase the probability of gravitational encounters among stellar systems during the early stages of evolution. Stellar interaction may occur through non-recurring, hyperbolic…
Recent ground and space-based observations show that stars with multiple planets are common in the galaxy. Most of these observational methods are biased toward detecting large planets near to their host stars. Because of these…
The discovery of planets around PSR~1257+12 suggests that planetary systems may be detected around the recycled pulsars found in globular clusters. Planetary systems in dense clusters have lifetimes to disruption due to perturbations by…
Gravitational lensing events provide unique opportunities to discover and study planetary systems and binaries. Here we build on previous work to explore the role that orbital motion can play in both identifying and learning more about…
We find a deficiency of binary stars moving on strongly retrograde Galactic orbits. No binary deficiencies are seen for U or W velocities, however. From theoretical analyses, we rule out preferential disruption of pre-existing binary stars…
Thousands of confirmed and candidate exoplanets have been identified in recent years. Consequently, theoretical research on the formation and dynamical evolution of planetary systems has seen a boost, and the processes of planet-planet…
Polar ring galaxies, where matter is in equilibrium in perpendicular orbits around spiral galaxies, are ideal objects to probe the 3D shapes of dark matter halos. The conditions to constrain the halos are that the perpendicular system does…
Motion of a point mass in gravitational fields of the Sun and of the galactic disk is studied. Fundamental features of the motion are found by investigating the time-averaged differential equations for orbital evolution. Several types of…
While the number of stellar-mass black holes detected in X-rays or as gravitational wave sources is steadily increasing, the known population remains orders of magnitude smaller than predicted by stellar evolution theory. A significant…
Nearby companions alter the evolution of massive stars in binary systems. Using a sample of Galactic massive stars in nearby young clusters, we simultaneously measure all intrinsic binary characteristics relevant to quantify the frequency…
Many astrophysical systems can be approximated as isothermal spheres. In an isothermal sphere, the ``foreground'' objects can act as lenses on ``background'' objects in the same distribution. We study gravitational lensing by a singular…
The process of neutron-mirror neutron oscillation, motivated by symmetric mirror dark matter models, is governed by two parameters: $n-n'$ mixing parameter $\delta$ and $n-n'$ mass splitting $\Delta$. For neutron mirror neutron oscillation…