The TROY project

II. Multi-technique constraints on exotrojans in nine planetary systems^{★,★★,★★★}

¹ European Southern Observatory (ESO), Alonso de Cordova 3107, Vitacura Casilla 19001, Santiago 19, Chile
e-mail: jlillobox@eso.org
² Physics Institute, Space Research and Planetary Sciences, Center for Space and Habitability – NCCR PlanetS, University of Bern, Bern, Switzerland
³ Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
⁴ Departmento Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
⁵ Sub-department of Astrophysics, Department of Physics, University of Oxford, Oxford OX1 3RH, UK
⁶ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
⁷ Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
⁸ IMCCE, Observatoire de Paris – PSL Research University, UPMC University Paris 06, University Lille 1, CNRS, 77 Avenue Denfert-Rochereau, 75014 Paris, France
⁹ Department of Physics, University of Coimbra, 3004-516 Coimbra, Portugal
¹⁰ CIDMA, Departamento de Física, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
¹¹ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
¹² Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
¹³ ESO, Karl Schwarzschild Strasse 2, 85748 Garching, Germany
¹⁴ Departmento de Astrofísica, Centro de Astrobiología (CSIC-INTA), ESAC Campus 28692 Villanueva de la Cañada, Madrid, Spain

Received: 26 April 2018
Accepted: 27 June 2018

Abstract

Context. Co-orbital bodies are the byproduct of planet formation and evolution, as we know from the solar system. Although planet-size co-orbitals do not exists in our planetary system, dynamical studies show that they can remain stable for long periods of time in the gravitational well of massive planets. Should they exist, their detection is feasible with the current instrumentation.

Aims. In this paper, we present new ground-based observations searching for these bodies co-orbiting with nine close-in (P < 5 days) planets, using various observing techniques. The combination of all of these techniques allows us to restrict the parameter space of any possible trojan in the system.

Methods. We used multi-technique observations, comprised of radial velocity, precision photometry, and transit timing variations, both newly acquired in the context of the TROY project and publicly available, to constrain the presence of planet-size trojans in the Lagrangian points of nine known exoplanets.

Results. We find no clear evidence of trojans in these nine systems through any of the techniques used down to the precision of the observations. However, this allows us to constrain the presence of any potential trojan in the system, especially in the trojan mass or radius vs. libration amplitude plane. In particular, we can set upper mass limits in the super-Earth mass regime for six of the studied systems.