HD 117214 debris disk: scattered-light images and constraints on the presence of planets^★,★★

¹ ETH Zurich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
e-mail: englern@phys.ethz.ch
² INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
³ CNRS, IPAG, Université Grenoble Alpes, IPAG, 38000 Grenoble, France
⁴ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
⁵ European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacua, Santiago 19, Chile
⁶ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁷ IKonkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly-Thege Miklós út 15-17, H-1121 Budapest, Hungary
⁸ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁹ Aix-Marseille Université, CNRS, LAM – Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
¹⁰ Anton Pannekoek Astronomical Institute, University of Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands
¹¹ Kiepenheuer-Institut für Sonnenphysik, Schneckstr. 6, 79104 Freiburg, Germany
¹² Geneva Observatory, University of Geneva, Chemin des Mailettes 51, 1290 Versoix, Switzerland
¹³ Centre de Recherche Astrophysique de Lyon, CNRS/ENSL Université Lyon 1, 9 av. Ch. André, 69561 Saint-Genis-Laval, France
¹⁴ Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USA
¹⁵ Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
¹⁶ Núcleo Milenio Formación Planetaria - NPF, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
¹⁷ Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
¹⁸ Escuela de Ingeniería Industrial, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
¹⁹ ONERA, The French Aerospace Lab BP72, 29 avenue de la Division Leclerc, 92322 Châtillon Cedex, France

Received: 2 October 2019
Accepted: 9 January 2020

Abstract

Context. Young stars with debris disks are the most promising targets for an exoplanet search because debris indicate a successful formation of planetary bodies. Debris disks can be shaped by planets into ring structures that give valuable indications on the presence and location of planets in the disk.

Aims. We performed observations of the Sco-Cen F star HD 117214 to search for planetary companions and to characterize the debris disk structure.

Methods. HD 117214 was observed with the SPHERE subsystems IRDIS, IFS, and ZIMPOL at optical and near-IR wavelengths using angular and polarimetric differential imaging techniques. This provided the first images of scattered light from the debris disk with the highest spatial resolution of 25 mas and an inner working angle <0.1″. With the observations with IRDIS and IFS we derived detection limits for substellar companions. The geometrical parameters of the detected disk were constrained by fitting 3D models for the scattering of an optically thin dust disk. Investigating the possible origin of the disk gap, we introduced putative planets therein and modeled the planet–disk and planet–planet dynamical interactions. The obtained planetary architectures were compared with the detection limit curves.

Results. The debris disk has an axisymmetric ring structure with a radius of 0.42(±0.01)″ or ~45 au and an inclination of 71(±2.5)° and exhibits a 0.4″ (~40 au) wide inner cavity. From the polarimetric data, we derive a polarized flux contrast for the disk of (F_pol)_disk/F_∗ = (3.1 ± 1.2) × 10⁻⁴ in the RI band.

Conclusions. The fractional scattered polarized flux of the disk is eight times lower than the fractional IR flux excess. This ratio is similar to the one obtained for the debris disk HIP 79977, indicating that dust radiation properties are similar for these two disks. Inside the disk cavity we achieve high-sensitivity limits on planetary companions with a mass down to ~4 M_J at projected radial separations between 0.2″ and 0.4″. We can exclude stellar companions at a radial separation larger than 75 mas from the star.