Abstract One of the common approximations in long-term evolution studies small bodies is use circular orbits averaging actual eccentric ones, facilitating coupling processes with very different timescales, such as orbital changes and thermal processing. Here we test a number schemes for elliptic context comets, aiming to identify one that best reproduces orbits’ heating patterns surface subsurf...

De la Peña 1980 and Puthoff 1987 show that circular orbits in the hydrogen problem of Stochastic Electrodynamics connect to a stable situation, where the electron neither collapses onto the nucleus nor gets expelled from the atom. Although the Cole-Zou 2003 simulations support the stability, our recent numerics always lead to self-ionisation. Here the de la Peña-Puthoff argument is extended to ...

We examine the evolution of highly eccentric, planet-crossing orbits in the restricted three-body problem (Sun, planet, comet). We construct a simple Keplerian map in which the comet energy changes instantaneously at perihelion, by an amount depending only on the azimuthal angle between the planet and the comet at the time of perihelion passage. This approximate but very fast mapping allow us t...

All four giant planets in the Solar system possess irregular satellites, characterized by large, highly eccentric and/or inclined orbits that are distinct from the nearly circular, uninclined orbits of the regular satellites. This difference can be traced directly to different modes of formation. Whereas the regular satellites grew by accretion within circumplanetary disks the irregular satelli...

We numerically explore the long-term stability of planetary orbits locked in a 2:1 mean motion resonance for a wide range of planetary mass ratios and orbital parameters. Our major tool is Laskar’s frequency map analysis. Regions of low diffusion rate are outlined in a phase space defined by the two planetary eccentricities and the libration amplitude of a critical resonance argument. Resonant ...

Zoom-whirl behavior has the reputation of being a rare phenomenon. The concern has been that gravitational radiation would drain angular momentum so rapidly that generic orbits would circularize before zoom-whirl behavior could play out, and only rare highly tuned orbits would retain their imprint. Using full numerical relativity, we catch zoom-whirl behavior despite dissipation. The larger the...

The effects of the Galactic bar on the velocity distribution of old disc stars in the Solar neighbourhood are investigated using high-resolution 2D test particle simulations. A detailed orbital analysis reveals that the structure of the U − V distribution in these simulations is closely related to the phase-space extent of regular and chaotic orbits. At low angular momentum and for a sufficient...

Using black hole perturbation theory, we calculate the gravitational waves produced by test particles moving on bound geodesic orbits about rotating black holes. The orbits we consider are generic — simultaneously eccentric and inclined. The waves can be described as having radial, polar, and azimuthal “voices”, each of which can be made to dominate by varying eccentricity and inclination. Alth...

The Habitable Zone Gallery is a new service to the exoplanet community that provides habitablezone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table with information on the percentage of orbital phase spent within the HZ, planetary effective temperatures, and other basic planetary properties. In addition to the t...

The hypervelocity star SDSS J090745.0+024507 in the halo of the Milky Way galaxy (Brown et al. 2005) most likely originated from the breakup of a binary star system by the central black hole, SgrA* (Hills 1988). We examine the fate of former binary companions to similar hypervelocity stars (HVSs) by simulating 600 different binary orbits around SgrA* with a direct N-body integration code. For s...