The tidal tails of 47 Tucanae


  • Richard R. Lane,

    Corresponding author
    1. Departamento de Astronomía, Universidad de Concepción, Casilla 160 C, Concepción, Chile
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  • Andreas H. W. Küpper,

    Corresponding author
    1. Argelander-Institut für Astronomie (AIfA), Auf dem Hügel 71, 53121 Bonn, Germany
    2. European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
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  • Douglas C. Heggie

    Corresponding author
    1. School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, King’s Buildings, Edinburgh EH9 3JZ
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This article is corrected by:

  1. Errata: Erratum: The tidal tails of 47 Tucanae Volume 426, Issue 1, 797–800, Article first published online: 20 September 2012

E-mail: (RRL); (AHWK); (DCH)


The Galactic globular cluster 47 Tucanae (47 Tuc) shows a rare increase in its velocity dispersion profile at large radii, indicative of energetic, yet bound, stars at large radii dominating the velocity dispersion and, potentially, of ongoing evaporation. Escaping stars will form tidal tails, as seen with several Galactic globular clusters; however, the tidal tails of 47 Tuc are yet to be uncovered. We model these tails of 47 Tuc using the most accurate input data available, with the specific aim of determining their locations, as well as the densities of the epicyclic overdensities within the tails. The overdensities from our models show an increase of 3–4 per cent above the Galactic background and, therefore, should be easily detectable using matched filtering techniques. We find that the most influential parameter with regard to both the locations and densities of the epicyclic overdensities is the heliocentric distance to the cluster. Hence, uncovering these tidal features observationally will contribute greatly to the ongoing problem of determining the distance to 47 Tuc, tightly constraining the distance of the cluster independent of other methods. Using our streakline method for determining the locations of the tidal tails and their overdensities, we show how, in principle, the shape and extent of the tidal tails of any Galactic globular cluster can be determined without resorting to computationally expensive N-body simulations.