A5031539287- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Planetary Science and Exploration
- Historical Economic and Social Studies
- Medieval Literature and History
- History and Developments in Astronomy
- Astrophysics and Star Formation Studies
- Space Science and Extraterrestrial Life
- Isotope Analysis in Ecology
- Galaxies: Formation, Evolution, Phenomena
- Historical Astronomy and Related Studies
- Historical Studies of British Isles
- Astronomical and nuclear sciences
- Medieval and Early Modern Justice
- Astronomy and Astrophysical Research
- Scottish History and National Identity
- Space Exploration and Technology
- Scientific Research and Discoveries
- Archaeology and ancient environmental studies
- Soil Moisture and Remote Sensing
- Space exploration and regulation
- Astrophysical Phenomena and Observations
- Vietnamese History and Culture Studies
- Byzantine Studies and History
- ICT in Developing Communities
University of East Anglia
2013-2024
MMA Design (United States)
2021-2023
St. Paul's Co-educational College
2014-2020
Engineering Associates (United States)
2018
Armagh Observatory & Planetarium
2000-2015
UK Centre for Ecology & Hydrology
2014-2015
Research School for Medieval Studies
2014
Icahn School of Medicine at Mount Sinai
2011
IBM (United States)
2010
Grammar School
2002-2008
Large-scale simulations of the Centaur population are carried out. The evolution 23328 particles based on orbits 32 well-known Centaurs is followed for up to 3 Myr in forward and backward direction under influence 4 massive planets. objects exhibit a rich variety dynamical behaviour with half-lives ranging from 540 kyr (1996 AR20) (2000 FZ53). mean half-life entire sample 2.7 Myr. data analyzed using classification scheme controlling planets at perihelion aphelion, previously given Horner et...
The structure and evolution of a hypothetical cloud comets surrounding the Solar System is investigated, with particular reference to showing how derived results depend on assumed cometary energy velocity distribution functions. mean transfer rate by stars giant molecular clouds calculated it shown that for reasonable values parameters cumulative effect dominant. Thus unlikely loosely-bound Oort comet could survive age System.
Gas flows in elliptical galaxies fuelled by stellar mass loss have been calculated numerically for three fiducial epochs using both King and de Vaucouleurs models of NGC 3379. Our results show that supernova heating is unable to prevent the inflow a large proportion lifetime most giant galaxies, irrespective their detailed structure. At present epoch, inwards those with mean line-of-sight velocity dispersion |$\bar \sigma \gt \sigma_ \text {tr} \simeq 300 \enspace {km}\enspace s^{-1}$|....
A numerical study of an ensemble orbits based on observed objects in the near-Neptune high-eccentricity (NNHE) region, with perihelion distances q range 28 < 35.5 au and semimajor axes a 60 1000 au, is used to predict orbital distribution Centaurs (5 au) for comparison observations after correcting discovery biases. The majority produced this way have a≲ au. However, intrinsic number dominated by longer period objects, > being roughly order magnitude greater than that therefore inconsistent...
A model of the Oort cloud has been developed by accounting for planetary, stellar and Galactic perturbations using numerical symplectic integrations covering 4.5 Gyr. The is consistent with broad dynamical characteristics observed cometary populations injected from into different regions Solar system. We show that majority high-eccentricity trans-Neptunian objects, Centaurs short-period comets have visited (a > 1000 au) during their history. Assuming observations near-parabolic flux absolute...
Observations of long-period comets and the mean terrestrial cratering rate over past 600 Myr are used to constrain parameters models Oort cometary cloud. Steady-state which explain observed near-parabolic flux number short-period generally require only a modest degree central concentration. Although range possible can satisfy data, typical example has power-law distribution orbital energies for semi-major axes greater than about 4000 AU with an energy spectral index γ=0.5. Such model might...
Recent observations of an unexpectedly high incidence bright Leonid meteors about 16 h before the predicted maximum main shower are explained by ejection dust grains into 5/14 mean-motion resonance with Jupiter, principally during perihelion passage Comet 55P/Tempel—Tuttle in 1333. The dynamical evolution resonant has following properties: first, do not spread uniformly around orbit, but instead librate a centre within stream; secondly, these zones contain much higher space density particles...
The mean energy transfer rate to comets in the Oort Cloud is calculated including both stellar and giant molecular cloud perturbations. For representative values of parameters clouds dominate evolution for semi-major axes |$\text{a}\gtrsim2\times{10}^{4}$|AU, while stars if |$\text{a}\lesssim2\times{10}^{4}$|AU. resulting unbinding time-scales half-lives are compared with results Bahcall et al. Hut & Tremaine. Good agreement their formulae obtained although there slight differences detailed...
The problem of the capture short-period comets from nearly parabolic orbits is investigated for initial with a wide range perihelia and inclinations. For less than about 9 AU, conventional picture by 'diffusive' process, involving many relatively small perturbations Jupiter to lesser extent Saturn, confirmed found approximately describe results. However, long-period beyond this distance typically suffer much weaker encounters hence require more revolutions before eventual capture....