Architecture of planetary systems with and without outer giant planets

I. Inner planet detections around HD 23079, HD 196067, and HD 86226

¹ Département d’astronomie, Université de Genève, chemin Pegasi 51, 1290 Versoix, Switzerland
² INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
³ Department of Physics, University of Oxford, Oxford OX13RH, UK
⁴ Instituto Tecnológico de Buenos Aires (ITBA), Iguazú 341, Buenos Aires, CABA C1437, Argentina
⁵ Instituto de Ciencias Físicas (CONICET / ECyT-UNSAM), Campus Miguelete, 25 de Mayo y Francia, (1650) Buenos Aires, Argentina
⁶ Aix Marseille Université, CNRS, CNES, LAM, Marseille, France
⁷ Department of Astronomy, Yale University, 52 Hillhouse Avenue, New Haven, CT 06511, USA
⁸ European Southern Observatory, Av. Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile
⁹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹⁰ Division of Space Research and Planetary Sciences, Physics Institute, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
¹¹ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
¹² Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

^★ Corresponding author: jean-baptiste.delisle@unige.ch

Received: 8 May 2025
Accepted: 5 September 2025

Abstract

Understanding the link between outer giant planets (OGPs) and inner light planets (ILPs) is key to understanding planetary system formation and architecture. The correlation between these two populations of planets is debated both theoretically – different formation models predict either a correlation or an anticorrelation – and observationally. Several recent attempts to constrain this correlation have yielded contradictory results, due to small-number statistics and heterogeneous samples. We present an ongoing long-term observational effort with CORALIE, HARPS, and ESPRESSO to probe the ILP occurrence in systems with and without OGP. In this first article of a series, we discuss how, from the design to the observations, we ensured the homogeneity of the samples, both in terms of stellar properties and observing strategy. We also present the first three detections of ILPs in our OGP host sample. We find a 8.3 m_⊕ planet at 5.75 d around HD 23079, a 10.4 m_⊕ planet at 4.6 d around HD 196067, and we confirm the 7.5 m_⊕ planet at 3.98 d around HD 86226. While a rigorous statistical analysis of our samples will be performed in subsequent studies, the relatively low number of detections in our sample seems to contradict previous studies that found a strong OGP-ILP correlation.