NGTS-7Ab: an ultrashort-period brown dwarf transiting a tidally locked and active M dwarf-Reference-Cited by-同舟云学术

NGTS-7Ab: an ultrashort-period brown dwarf transiting a tidally locked and active M dwarf

Published:2019-09-11 Issue:4 Volume:489 Page:5146-5164
ISSN:0035-8711
Container-title:Monthly Notices of the Royal Astronomical Society
language:en
Short-container-title:

Author:

Jackman James A G¹²^ORCID,Wheatley Peter J¹²^ORCID,Bayliss Dan¹²^ORCID,Gill Samuel¹²,Hodgkin Simon T³,Burleigh Matthew R⁴,Braker Ian P⁴,Günther Maximilian N⁵⁶,Louden Tom¹²^ORCID,Turner Oliver⁷^ORCID,Anderson David R¹²^ORCID,Belardi Claudia⁴,Bouchy François⁷,Briegal Joshua T⁵,Bryant Edward M¹²,Cabrera Juan⁸,Casewell Sarah L⁴,Chaushev Alexander⁹,Costes Jean C¹⁰,Csizmadia Szilard⁸^ORCID,Eigmüller Philipp⁸,Erikson Anders⁸,Gänsicke Boris T¹^ORCID,Gillen Edward⁵^ORCID,Goad Michael R⁴,Jenkins James S¹¹¹²,McCormac James¹²,Moyano Maximiliano¹³,Nielsen Louise D⁸^ORCID,Pollacco Don¹²,Poppenhaeger Katja¹⁰¹⁴^ORCID,Queloz Didier⁵,Rauer Heike⁸⁹¹⁵,Raynard Liam⁴,Smith Alexis M S⁸,Udry Stéphane⁷,Vines Jose I¹¹,Watson Christopher A¹⁰,West Richard G¹²^ORCID

Affiliation:

1. Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

2. Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

3. Institute of Astronomy, University of Cambridge, Madingley Rise, Cambridge CB3 0HA, UK

4. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK

5. Astrophysics Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK

6. Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

7. Geneva Observatory, University of Geneva, Chemin des Mailettes 51, CH-1290 Versoix, Switzerland

8. Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, D-12489 Berlin, Germany

9. Center for Astronomy and Astrophysics, TU Berlin, Hardenbergstr 36, D-10623 Berlin, Germany

10. Astrophysics Research Centre, Queen’s University Belfast, 1 University Road, Belfast BT7 1NN, UK

11. Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

12. Centro de Astrofísica y Tecnologías Afines (CATA), Casilla 36-D, Santiago, Chile

13. Instituto de Astronomía, Universidad Católica del Norte, Angamos 0610, 1270709 Antofagasta, Chile

14. Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany

15. Institute of Geological Sciences, FU Berlin, Malteserstr 74–100, D-12249 Berlin, Germany

Abstract

ABSTRACT We present the discovery of NGTS-7Ab, a high-mass brown dwarf transiting an M dwarf with a period of 16.2 h, discovered as part of the Next Generation Transit Survey (NGTS). This is the shortest period transiting brown dwarf around a main or pre-main sequence star to date. The M star host (NGTS-7A) has an age of roughly 55 Myr and is in a state of spin–orbit synchronization, which we attribute to tidal interaction with the brown dwarf acting to spin-up the star. The host star is magnetically active and shows multiple flares across the NGTS and follow-up light curves, which we use to probe the flare–star-spot phase relation. The host star also has an M star companion at a separation of 1.13 arcsec with very similar proper motion and systemic velocity, suggesting that the NGTS-7 system is a hierarchical triple. The combination of tidal synchronisation and magnetic braking is expected to drive on-going decay of the brown dwarf orbit, with a remaining lifetime of only 5–10 Myr.

Funder

University of Warwick

University of Leicester

Queen’s University Belfast

University of Genev

Deutsches Zentrum für Luft- und Raumfahrt

University of Cambridge

Science and Technology Facilities Council

Fondo Nacional de Desarrollo Científico y Tecnológico

Consejo Nacional de Innovación, Ciencia y Tecnología

California Institute of Technology

National Aeronautics and Space Administration