Letter to the Editor

New disk discovered with VLT/SPHERE around the M star GSC 07396−00759^★

¹ INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
e-mail: elena.sissa@oapd.inaf.it
² Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
⁴ Núcleo Milenio Formación Planetaria – NPF, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
⁵ Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁶ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁷ CRAL, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
⁸ LESIA, Observatoire de Paris-Meudon, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
⁹ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹⁰ Dipartimento di Fisica e Astronomia – Universita’ di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
¹¹ INCT, Universidad De Atacama, calle Copayapu 485, Copiapó, Atacama, Chile
¹² INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
¹³ Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
¹⁴ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
¹⁵ Department of Astronomy, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
¹⁶ Exoplanets and Stellar Astrophysics Laboratory, Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20770, USA
¹⁷ Institute for Particle Physics and Astrophysics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
¹⁸ Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zürich, Winterthurestrasse 190, 8057 Zürich, Switzerland
¹⁹ Anton Pannekoek Institute for Astronomy, Science Park 904, 1098 XH Amsterdam, The Netherlands

Received: 31 January 2018
Accepted: 26 February 2018

Abstract

Debris disks are usually detected through the infrared excess over the photospheric level of their host star. The most favorable stars for disk detection are those with spectral types between A and K, while the statistics for debris disks detected around low-mass M-type stars is very low, either because they are rare or because they are more difficult to detect. Terrestrial planets, on the other hand, may be common around M-type stars. Here, we report on the discovery of an extended (likely) debris disk around the M-dwarf GSC 07396−00759. The star is a wide companion of the close accreting binary V4046 Sgr. The system probably is a member of the β Pictoris Moving Group. We resolve the disk in scattered light, exploiting high-contrast, high-resolution imagery with the two near-infrared subsystems of the VLT/SPHERE instrument, operating in the Y J bands and the H2H3 doublet. The disk is clearly detected up to 1.5^′′ (~110 au) from the star and appears as a ring, with an inclination i ~ 83°, and a peak density position at ~70 au. The spatial extension of the disk suggests that the dust dynamics is affected by a strong stellar wind, showing similarities with the AU Mic system that has also been resolved with SPHERE. The images show faint asymmetric structures at the widest separation in the northwest side. We also set an upper limit for the presence of giant planets to 2 M_J. Finally, we note that the 2 resolved disks around M-type stars of 30 such stars observed with SPHERE are viewed close to edge-on, suggesting that a significant population of debris disks around M dwarfs could remain undetected because of an unfavorable orientation.