A tale of caution: the tails of open clusters are much longer than thought, but more difficult to find

Henri Boffin
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The tidal tails of stellar clusters are an important tool for studying the clusters’ birth conditions, their evolution, coupling, and interaction with the Galactic potential, and to understand how field stars populate the Milky Way. Thanks to Gaia, much progress has been accomplished in finding tails of open clusters. We will show here that the physical size of such tidal tails is larger than previously thought. Their identification requires combining the sophisticated analysis of the Gaia catalogue using machine learning techniques to the use of N-body simulations and the new compact convergent point method. We will highlight recent results about the tails of the Hyades and of NGC 752, which extend over several hundreds of parsecs and present puzzling asymmetries that likely provide constraints on the potential of Milky Way. Finally, we will also present the extension of our studies to a large ensemble of open clusters and show how our analysis opens a completely new window on the study of open clusters, whose potential will be fully unleashed with future Gaia data releases.