University of Hertfordshire

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From the same journal

By the same authors

Was Proxima captured by alpha Centauri A and B?

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Original languageEnglish
Article numberstx2576
Pages (from-to)3185-3189
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Early online date5 Oct 2017
Publication statusPublished - 21 Jan 2018


The nearest stellar system consists of the stars Proxima, Alpha Centauri A and B and at least one planet Proxima b. The habitability of Proxima b and any other planets are likely to be significantly influenced by the orbital evolution of the system. To study the dynamical evolution of the system, we simulate the motions of Proxima and Alpha Centauri A and B due to the perturbations from the Galactic tide and stellar encounters in a Monte Carlo fashion. From 100 clones, we find that 74 per cent orbits of Proxima Centauri are bound to Alpha Centauri A and B while 17 per cent and 9 per cent orbits become unbound in the simulations over the past and future 5Gyr. If the system migrated outward in the Milky Way to its current location, more than 50 per cent of clones could become unstable in backward simulations. The ratio of unstable clones increases with the simulation time-scale and encounter rate. This provides some evidence for a capture scenario for the formation of the current triple system. Despite large uncertainties, the metallicity difference between Proxima and Alpha Centauri A and B is also suggestive of their different origin. None the less, further improvements in the available data and models will be necessary for a reliable assessment of the history of the Proxima-Alpha Centauri system and its impact on the habitability of Proxima b.


This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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