University of Hertfordshire

From the same journal

From the same journal

By the same authors

Understanding Fomalhaut as a Cooper pair

Research output: Contribution to journalArticlepeer-review


  • 1710.07184v2

    Accepted author manuscript, 444 KB, PDF document

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Original languageEnglish
Pages (from-to)4412-4420
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Early online date5 Dec 2017
Publication statusPublished - 11 Mar 2018


Fomalhaut is a nearby stellar system and has been found to be a triple based on astrometric observations. With new radial velocity and astrometric data, we study the association between Fomalhaut A, B, and C in a Bayesian framework, finding that the system is gravitationally bound or at least associated. Based on simulations of the system, we find that Fomalhaut C can be easily destabilized through combined perturbations from the Galactic tide and stellar encounters. Considering that observing the disruption of a triple is probably rare in the solar neighbourhood, we conclude that Fomalhaut C is a so-called 'gravitational pair' of Fomalhaut A and B. Like the Cooper pair mechanism in superconductors, this phenomenon only appears once the orbital energy of a component becomes comparable with the energy fluctuations caused by the environment. Based on our simulations, we find (1) an upper limit of 8 kms -1 velocity difference is appropriate when selecting binary candidates, and (2) an empirical formula for the escape radius, which is more appropriate than tidal radius when measuring the stability of wide binaries.


This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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