Discovery of a cold giant planet and mass measurement of a hot super-Earth in the multi-planetary system WASP-132

¹ Observatoire de Genève, Université de Genève, 51 Chemin Pegasi, 1290 Versoix, Switzerland
² Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, UK
³ Center for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry, UK
⁴ Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
⁵ Center for Theoretical Astrophysics & Cosmology, Institute for Computational Science, University of Zurich, Zürich, Switzerland
⁶ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CauP, Rua das Estrelas, 4150-762 Porto, Portugal
⁷ Dep. de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
⁸ Centro de Astrobiología (CAB), CSIC-INTA, Dep. de Astrofísica, ESAC campus, 28692 Villanueva de la Cañada (Madrid), Spain
⁹ European Southern Observatory, Karl-Schwarzschild-Strasse 3, 85748 Garching, Germany

^★ Corresponding author; nolangrieves@gmail.com

Received: 6 October 2023
Accepted: 25 November 2024

Abstract

Hot Jupiters generally do not have nearby planet companions, as they may have cleared out other planets during their inward migration from more distant orbits. This gives evidence that hot Jupiters more often migrate inward via high-eccentricity migration due to dynamical interactions between planets rather than more dynamically cool migration mechanisms through the protoplanetary disk. Here we further refine the unique system of WASP-132 by characterizing the mass of the recently validated 1.0-day period super-Earth WASP-132c (TOI-822.02), interior to the 7.1-day period hot Jupiter WASP-132b. Additionally, we announce the discovery of a giant planet at a 5-year period (2.7 AU). We also detected a long-term trend in the radial velocity data indicative of another outer companion. Using over nine years of CORALIE radial velocities (RVs) and over two months of highly sampled HARPS RVs, we determined the masses of the planets from smallest to largest orbital period to be M_c = 6.26_−1.83^+1.84 M_⊕, M_b = 0.428_−0.015^+0.015 M_Jup, and M_d = sin i 5.16_−0.52^+0.52 M_Jup, respectively. Using TESS and CHEOPS photometry data, we measured the radii of the two inner transiting planets to be R_c = 1.841_−0.093^+0.094 R_⊕ and R_b = 0.901_−0.038^+0.038 R_Jup. We find a bulk density of ρ_c = 5.47_−1.71^+1.96 g cm⁻³ for WASP-132c, which is slightly above the Earth-like composition line on the mass-radius diagram. WASP-132 is a unique multi-planetary system in that both an inner rocky planet and an outer giant planet are in a system with a hot Jupiter. This suggests it migrated via a rarer dynamically cool mechanism and helps to further our understanding of how hot Jupiter systems form and evolve.