Examinando por Autor "Raymond, Sean N."

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    A rich population of free-floating planets in the Upper Scorpius young stellar association
    (Springer Nature, 2021-12-22) Miret Roig, Nuria; Bouy, Hervé; Raymond, Sean N.; Tamura, Motohide; Bertin, Emmanuel; Barrado, David; Olivares Romero, Javier; Galli, P. A. B.; Cuillandre, Jean-Charles; Sarro Baro, Luis Manuel; Berihuete, Ángel; Huelamo, Nuria; https://orcid.org/0000-0001-5292-0421; https://orcid.org/0000-0002-7084-487X; https://orcid.org/0000-0001-8974-0758; https://orcid.org/0000-0002-6510-0681; https://orcid.org/0000-0002-3602-3664; https://orcid.org/0000-0002-5971-9242; https://orcid.org/0000-0003-2271-9297; https://orcid.org/0000-0002-3263-8645; https://orcid.org/0000-0002-8589-4423; https://orcid.org/0000-0002-2711-8143
    Free-floating planets (FFPs) are planetary-mass objects that are not bound to host stars. First discovered in the 1990s, their nature and origin are still largely unconstrained because of a lack of large homogeneous samples enabling a statistical analysis of their properties. To date, most FFPs have been discovered using indirect methods; micro-lensing surveys have proven particularly successful to detect these objects down to a few Earth masses1, 2. However, the ephemeral nature of micro-lensing events prevents any follow-up observations and individual characterisation. Several studies have identified FFPs in young stellar clusters3, 4 and the Galactic field5 but their samples are small or heterogeneous in age and origin. Here we report the discovery of between 70 and 170 FFPs (depending on the assumed age) in the region encompassing Upper Scorpius (USC) and Ophiuchus (Oph), the closest young OB association to the Sun. It is the largest homogeneous sample of nearly coeval FFPs discovered to date. We found an excess of FFPs by a factor of up to seven compared to core-collapse models predictions6–8, demonstrating that other formation mechanisms may be at work. We estimate that ejection from planetary systems might have a contribution comparable to that of core-collapse in the formation of FFPs. Therefore, ejections due to dynamical instabilities in giant exoplanet systems must be frequent within the first 10 Myr of a system’s life.