A

A scaled-up planetary system around a supernova progenitor

Astronomy and Astrophysics, vol. 664, pp. A9

Abstract

Context. Virtually all known exoplanets reside around stars with M < 2.3 M⊙ either due to the rapid evaporation of the protostellar disks or to selection effects impeding detections around more massive stellar hosts. Aims. To clarify if this dearth of planets is real or a selection effect, we launched the planet-hunting B-star Exoplanet Abundance STudy (BEAST) survey targeting B stars (M > 2.4 M⊙) in the young (5−20 Myr) Scorpius-Centaurus association by means of the high-contrast spectro-imager SPHERE at the Very Large Telescope. Methods. In this paper we present the analysis of high-contrast images of the massive (M ~ 9 M⊙) star μ2 Sco obtained within BEAST. We carefully examined the properties of this star, combining data from Gaia and from the literature, and used state-of-the-art algorithms for the reduction and analysis of our observations. Results. Based on kinematic information, we found that μ2 Sco is a member of a small group which we label Eastern Lower Scorpius within the Scorpius-Centaurus association. We were thus able to constrain its distance, refining in turn the precision on stellar parameters. Around this star we identify a robustly detected substellar companion (14.4 ± 0.8 MJ)at a projected separation of 290 ± 10 au, and a probable second similar object (18.5 ± 1.5 MJ) at 21 ± 1 au. The planet-to-star mass ratios of these objects are similar to that of Jupiter to the Sun, and the flux they receive from the star is similar to those of Jupiter and Mercury, respectively. Conclusions. The robust and the probable companions of μ2 Sco are naturally added to the giant 10.9 MJ planet recently discovered by BEAST around the binary b Cen system. While these objects are slightly more massive than the deuterium burning limit, their properties are similar to those of giant planets around less massive stars and they are better reproduced by assuming that they formed under a planet-like, rather than a star-like scenario. Irrespective of the (needed) confirmation of the inner companion, μ2 Sco is the first star that would end its life as a supernova that hosts such a system. The tentative high frequency of BEAST discoveries is unexpected, and it shows that systems with giant planets or small-mass brown dwarfs can form around B stars. When putting this finding in the context of core accretion and gravitational instability formation scenarios, we conclude that the current modeling of both mechanisms is not able to produce this kind of companion. The completion of BEAST will pave the way for the first time to an extension of these models to intermediate and massive stars.

Authors 27

  1. University of Padua · Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    Department of Physics and Astronomy ‘Galileo Galilei’, University of Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    Department of Physics and Astronomy 'Galileo Galilei', University of Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

  2. Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

  3. Stockholm University · AlbaNova

    Affiliation as printed

    Institutionen för astronomi, Stockholms universitet, AlbaNova universitetscentrum, 106 91 Stockholm, Sweden

  4. California Institute of Technology · Jet Propulsion Laboratory

    Affiliation as printed

    Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 USA

  5. Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · University of Chile · Université Grenoble Alpes

    Affiliation as printed

    Unidad Mixta Internacional Franco-Chilena de Astronomía, CNRS/INSU UMI 3386 and Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

    Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

  6. Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

  7. Lyon 1 Université · Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon

    Affiliation as printed

    CRAL, UMR 5574, CNRS, Université Lyon 1, 9 avenue Charles André, 69561 Saint-Genis-Laval Cedex, France

  8. Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille

    Affiliation as printed

    Aix-Marseille Université, CNRS, CNES, LAM (Laboratoire d’Astrophysique de Marseille), UMR 7326, 13388 Marseille, France

    Aix-Marseille Université, CNRS, CNES, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 13388 Marseille, France

  9. Stockholm University · AlbaNova

    Affiliation as printed

    Institutionen för astronomi, Stockholms universitet, AlbaNova universitetscentrum, 106 91 Stockholm, Sweden

  10. Universidad Autónoma de Madrid

    Affiliation as printed

    Centro de Investigación Avanzada en Física Fundamental (CIAFF), Facultad de Ciencias, UAM, 28049 Madrid, Spain

    Departamento de Física Teórica, Universidad Autónoma de Madrid, 28049 Madrid, Spain

  11. Heidelberg University

    Affiliation as printed

    Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany

  12. Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands

  13. University of Michigan

    Affiliation as printed

    Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109 USA

  14. Lyon 1 Université · Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon

    Affiliation as printed

    CRAL, UMR 5574, CNRS, Université Lyon 1, 9 avenue Charles André, 69561 Saint-Genis-Laval Cedex, France

  15. The Open University

    Affiliation as printed

    School of Physical Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK

  16. Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

  17. Stockholm University · AlbaNova

    Affiliation as printed

    Institutionen för astronomi, Stockholms universitet, AlbaNova universitetscentrum, 106 91 Stockholm, Sweden

  18. Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

  19. Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

  20. ETH Zurich · Institute for Particle Physics and Astrophysics

    Affiliation as printed

    ETH Zürich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland

  21. Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

  22. Osservatorio di Astrofisica e Scienza dello Spazio · University of Birmingham · National Institute for Astrophysics · University of Bologna

    Affiliation as printed

    Dipartimento di Fisica e Astronomia Augusto Righi, Università degli Studi di Bologna, Via Gobetti 93/2, I-40129 Bologna, Italy

    INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via Gobetti 93/3, I-40129 Bologna, Italy

    School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom

  23. Max Planck Institute for Astronomy

    Affiliation as printed

    Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

  24. ETH Zurich · Institute for Particle Physics and Astrophysics

    Affiliation as printed

    ETH Zürich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland

  25. University of Zurich

    Affiliation as printed

    Center for Theoretical Physics and Cosmology, Institute for Computational Science, Universität Zürich, Winterthurerstrasse 190, 8056 Zürich, Switzerland

  26. Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Sorbonne Paris Cité · Laboratoire d’études spatiales et d’instrumentation en astrophysique

    Affiliation as printed

    LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 Place Jules Janssen, 92195 Meudon, France

  27. University of Bern · Max Planck Institute for Astronomy · University of Tübingen

    Affiliation as printed

    Institut für Astronomie und Astrophysik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany

    Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

    Physikalisches Institut, Universität Bern, Gesellschaftsstr. 6, 3012 Bern, Switzerland

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References 131