Journal Article

Disrupting primordial planet signatures: the close encounter of two single-planet exosystems in the Galactic disc

Dimitri Veras and Nickolas Moeckel

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 425, issue 1, pages 680-700
Published in print September 2012 | ISSN: 0035-8711
Published online September 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21552.x
Disrupting primordial planet signatures: the close encounter of two single-planet exosystems in the Galactic disc

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Abstract

During their main-sequence lifetimes, the majority of all Galactic disc field stars must endure at least one stellar intruder passing within a few hundred au. Mounting observations of planet–star separations near or beyond this distance suggest that these close encounters may fundamentally shape currently observed orbital architectures and hence obscure primordial orbital features. We consider the commonly occurring fast close encounters of two single-planet systems in the Galactic disc, and investigate the resulting change in the planetary eccentricity and semimajor axis. We derive explicit four-body analytical limits for these variations and present numerical cross-sections which can be applied to localized regions of the Galaxy. We find that each wide-orbit planet has a few per cent chance of escape and an eccentricity that will typically change by at least 0.1 due to these encounters. The orbital properties established at formation of millions of tight-orbit Milky Way exoplanets are likely to be disrupted.

Keywords: celestial mechanics; planets and satellites: dynamical evolution and stability; planet–star interactions; stars: kinematics and dynamics; Galaxy: kinematics and dynamics; Galaxy: structure

Journal Article.  11175 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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