YSES 2b is a background star

Astronomy and Astrophysics, vol. 701, pp. A104

Abstract

Aims. We wish to confirm the nature of YSES 2b, a purportedly faint companion of the young star YSES 2. Methods. We used on-sky observations from SPHERE and GRAVITY to measure the astrometric position of 2b with respect to the star YSES 2, and examined the competing hypotheses of (i) a bound substellar companion versus (ii) a distant unrelated background source with a non-zero proper motion. Results. YSES 2b appears to be a late-type M-dwarf star over 2 kiloparsecs behind the star YSES 2. It has a transverse velocity of ∼300 km s−1 and is located within one of the spiral arms of the Galaxy. The main discriminant was multiple epochs of GRAVITY astrometry that identified the sub-milliarcsecond parallactic motion of the star.

Authors 16

1. Matthew A. Kenworthy Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

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

2. T. Stolker Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

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

3. Jens Kammerer

   European Southern Observatory

   Affiliation as printed

   European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching, Germany

4. William O. Balmer

   Johns Hopkins University

   Affiliation as printed

   Department of Physics & Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA

5. A. Vigan

   Centre National de la Recherche Scientifique · Aix-Marseille Université

   Affiliation as printed

   Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France

6. S. Lacour

   Centre National de la Recherche Scientifique · Université Paris Cité · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · CY Cergy Paris Université

   Affiliation as printed

   LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS, 92190 Meudon, France

7. Gilles P. P. L. Otten

   Institute of Astronomy and Astrophysics, Academia Sinica · Academia Sinica

   Affiliation as printed

   Academia Sinica, Institute of Astronomy and Astrophysics, 11F Astronomy-Mathematics Building, NTU/AS campus, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan

8. Eric E. Mamajek

   California Institute of Technology · Jet Propulsion Laboratory

   Affiliation as printed

   Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, M/S 321-162, Pasadena, CA, 91109, USA

9. C. Ginski

   Ollscoil na Gaillimhe – University of Galway

   Affiliation as printed

   School of Natural Sciences, Center for Astronomy, University of Galway, Galway, H91 CF50, Ireland

10. Mathias Nowak

    Centre National de la Recherche Scientifique · Université Paris Cité · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · CY Cergy Paris Université

    Affiliation as printed

    LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS, 92190 Meudon, France

11. Steven Martos

    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

12. Jason Wang

    Northwestern University

    Affiliation as printed

    Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA

13. Emily L. Rickman

    Space Telescope Science Institute · European Space Agency

    Affiliation as printed

    European Space Agency (ESA), ESA Office, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

14. M. Janson

    Stockholm University · AlbaNova

    Affiliation as printed

    Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden

15. Alexander J. Bohn Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

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

16. M. Bonavita

    Royal Observatory

    Affiliation as printed

    Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, Scotland, UK