arXiv subjects

Dimitri Veras

Publications and source records attributed to Dimitri Veras.

165 records · Page 10Linked to original sources

arXiv2005

Influence of massive planet scattering on nascent terrestrial planets

In most extrasolar planetary systems, the present orbits of known giant planets admit the existence of stable terrestrial planets. Those same giant planets, however, have typically eccentric orbits that hint at violent early dynamics less benign for low mass planet formation. Under the assumption that massive planet eccentricities are the end point of gravitational scattering in multiple planet systems, we study the evolution of the building blocks of terrestrial planets during the scattering process. We find that typically, evolutionary sequences that result in a moderately eccentric giant planet orbiting at a ~ 2.5 AU eject over 95% of the material initially present within the habitable zone. Crossing orbits largely trigger the ejection, and leave the surviving material with a wide dispersion in semi-major axis, eccentricity and inclination. Based on these results, we predict that radial velocity follow-up of terrestrial planet systems found by Kepler will find that these are anti-correlated with the presence of eccentric giant planets orbiting at a few AU.

astro-ph↗

arXiv2004

The Dynamics of Two Massive Planets on Inclined Orbits

The significant orbital eccentricities of most giant extrasolar planets may have their origin in the gravitational dynamics of initially unstable multiple planet systems. In this work, we explore the dynamics of two close planets on inclined orbits through both analytical techniques and extensive numerical scattering experiments. We derive a criterion for two equal mass planets on circular inclined orbits to achieve Hill stability, and conclude that significant radial migration and eccentricity pumping of both planets occurs predominantly by 2:1 and 5:3 mean motion resonant interactions. Using Laplace-Lagrange secular theory, we obtain analytical secular solutions for the orbital inclinations and longitudes of ascending nodes, and use those solutions to distinguish between the secular and resonant dynamics which arise in numerical simulations. We also illustrate how encounter maps, typically used to trace the motion of massless particles, may be modified to reproduce the gross instability seen by the numerical integrations. Such a correlation suggests promising future use of such maps to model the dynamics of more coplanar massive planet systems.

astro-ph↗

arXiv2003

Migration of extrasolar planets to large orbital radii

Observations of structure in circumstellar debris discs provide circumstantial evidence for the presence of massive planets at large (several tens of au) orbital radii, where the timescale for planet formation via core accretion is prohibitively long. Here, we investigate whether a population of distant planets can be produced via outward migration subsequent to formation in the inner disc. Two possibilities for significant outward migration are identified. First, cores that form early at radii of around 10 au can be carried to larger radii via gravitational interaction with the gaseous disc. This process is efficient if there is strong mass loss from the disc - either within a cluster or due to photoevaporation from a star more massive than the Sun - but does not require the extremely destructive environment found, for example, in the core of the Orion Nebula. We find that, depending upon the disc model, gas disc migration can yield massive planets (several Jupiter masses) at radii of around 20-50 au. Second, interactions within multiple planet systems can drive the outer planet into a large, normally highly eccentric orbit. A series of scattering experiments suggests that this process is most efficient for lower mass planets within systems of unequal mass ratio. This mechanism is a good candidate for explaining the origin of relatively low mass giant planets in eccentric orbits at large radii.

astro-ph↗