9 research outputs found
Continuation and stability deduction of resonant periodic orbits in three dimensional systems
In dynamical systems of few degrees of freedom, periodic solutions consist
the backbone of the phase space and the determination and computation of their
stability is crucial for understanding the global dynamics. In this paper we
study the classical three body problem in three dimensions and use its dynamics
to assess the long-term evolution of extrasolar systems. We compute periodic
orbits, which correspond to exact resonant motion, and determine their linear
stability. By computing maps of dynamical stability we show that stable
periodic orbits are surrounded in phase space with regular motion even in
systems with more than two degrees of freedom, while chaos is apparent close to
unstable ones. Therefore, families of stable periodic orbits, indeed, consist
backbones of the stability domains in phase space.Comment: Proceedings of the 6th International Conference on Numerical Analysis
(NumAn 2014). Published by the Applied Mathematics and Computers Lab,
Technical University of Crete (AMCL/TUC), Greec
Multi-Planet Destabilisation and Escape in Post-Main Sequence Systems
Discoveries of exoplanets orbiting evolved stars motivate critical
examinations of the dynamics of -body systems with mass loss. Multi-planet
evolved systems are particularly complex because of the mutual interactions
between the planets. Here, we study the underlying dynamical mechanisms which
can incite planetary escape in two-planet post-main sequence systems. Stellar
mass loss alone is unlikely to be rapid and high enough to eject planets at
typically-observed separations. However, the combination of mass loss and
planet-planet interactions can prompt a shift from stable to chaotic regions of
phase space. Consequently, when mass loss ceases, the unstable configuration
may cause escape. By assuming a constant stellar mass loss rate, we utilize
maps of dynamical stability to illustrate the distribution of regular and
chaotic trajectories in phase space. We show that chaos can drive the planets
to undergo close encounters, leading to the ejection of one planet. Stellar
mass loss can trigger the transition of a planetary system from a stable to
chaotic configuration, subsequently causing escape. We find that mass loss
non-adiabatically affects planet-planet interaction for the most massive
progenitor stars which avoid the supernova stage. For these cases, we present
specific examples of planetary escape.Comment: Accepted for publication in MNRAS (2013
Interaction of free-floating planets with a star-planet pair
The recent discovery of free-floating planets and their theoretical
interpretation as celestial bodies, either condensed independently or ejected
from parent stars in tight clusters, introduced an intriguing possibility.
Namely, that some exoplanets are not condensed from the protoplanetary disk of
their parent star. In this novel scenario a free-floating planet interacts with
an already existing planetary system, created in a tight cluster, and is
captured as a new planet. In the present work we study this interaction process
by integrating trajectories of planet-sized bodies, which encounter a binary
system consisting of a Jupiter-sized planet revolving around a Sun-like star.
To simplify the problem we assume coplanar orbits for the bound and the
free-floating planet and an initially parabolic orbit for the free-floating
planet. By calculating the uncertainty exponent, a quantity that measures the
dependence of the final state of the system on small changes of the initial
conditions, we show that the interaction process is a fractal classical
scattering. The uncertainty exponent is in the range (0.2-0.3) and is a
decreasing function of time. In this way we see that the statistical approach
we follow to tackle the problem is justified. The possible final outcomes of
this interaction are only four, namely flyby, planet exchange, capture or
disruption. We give the probability of each outcome as a function of the
incoming planet's mass. We find that the probability of exchange or capture (in
prograde as well as retrograde orbits and for very long times) is
non-negligible, a fact that might explain the possible future observations of
planetary systems with orbits that are either retrograde or tight and highly
eccentric.Comment: 19 pages, 12 figure
History and evolution of concepts in physics
Our understanding of nature, and in particular of physics and the laws governing it, has changed radically since the days of the ancient Greek natural philosophers. This book explains how and why these changes occurred, through landmark experiments as well as theories that - for their time - were revolutionary. The presentation covers Mechanics, Optics, Electromagnetism, Thermodynamics, Relativity Theory, Atomic Physics and Quantum Physics. The book places emphasis on ideas and on a qualitative presentation, rather than on mathematics and equations. Thus, although primarily addressed to those who are studying or have studied science, it can also be read by non-specialists. The author concludes with a discussion of the evolution and organization of universities, from ancient times until today, and of the organization and dissemination of knowledge through scientific publications and conferences
History and Evolution of Concepts in Physics
Our understanding of nature, and in particular of physics and the laws governing it, has changed radically since the days of the ancient Greek natural philosophers. This book explains how and why these changes occurred, through landmark experiments as well as theories that - for their time - were revolutionary. The presentation covers Mechanics, Optics, Electromagnetism, Thermodynamics, Relativity Theory, Atomic Physics and Quantum Physics. The book places emphasis on ideas and on a qualitative presentation, rather than on mathematics and equations. Thus, although primarily addressed to those who are studying or have studied science, it can also be read by non-specialists. The author concludes with a discussion of the evolution and organization of universities, from ancient times until today, and of the organization and dissemination of knowledge through scientific publications and conferences