A dynamical analysis of the proposed circumbinary HWVirginis planetary system

Horner, J. and Hinse, T. C. and Wittenmyer, R. A. and Marshall, J. P. and Tinney, C. G. (2012) A dynamical analysis of the proposed circumbinary HWVirginis planetary system. Monthly Notices of the Royal Astronomical Society, 427 (4). pp. 2812-2823. ISSN 0035-8711

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In 2009, the discovery of two planets orbiting the evolved binary star system HWVirginis (HWVir) was announced, based on systematic variations in the timing of eclipses between the two stars. The planets invoked in that work were significantly more massive than Jupiter, and moved on orbits that were mutually crossing - an architecture which suggests that mutual encounters and strong gravitational interactions are almost guaranteed. In this work, we perform a highly detailed analysis of the proposed HWVir planetary system. First, we consider the dynamical stability of the system as proposed in the discovery work. Through a mapping process involving 91 125 individual simulations, we find that the system is so unstable that the planets proposed simply cannot exist, due to mean lifetimes of less than a thousand years across the whole parameter space. We then present a detailed re-analysis of the observational data on HWVir, deriving a new orbital solution that provides a very good fit to the observational data. Our new analysis yields a system with planets more widely spaced, and of lower mass, than that proposed in the discovery work, and yields a significantly greater (and more realistic) estimate of the uncertainty in the orbit of the outermost body. Despite this, a detailed dynamical analysis of this new solution similarly reveals that it also requires the planets to move on orbits that are simply not dynamically feasible. Our results imply that some mechanism other than the influence of planetary companions must be the principal cause of the observed eclipse timing variations for HWVir. If the system does host exoplanets, they must move on orbits differing greatly from those previously proposed. Our results illustrate the critical importance of performing dynamical analyses as a part of the discovery process for multiple-planet exoplanetary systems.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2012 The Authors.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Mechanical and Mechatronic Engineering
Date Deposited: 26 Jun 2014 01:23
Last Modified: 06 Feb 2018 01:29
Uncontrolled Keywords: close-binaries; dynamical evolution and stability-binaries; eclipsing; Hwvir-planetary systems; planets and satellites
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020105 General Relativity and Gravitational Waves
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020108 Planetary Science (excl. Extraterrestrial Geology)
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1111/j.1365-2966.2012.22046.x
URI: http://eprints.usq.edu.au/id/eprint/25363

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