Star-planet connection through metallicity

¹ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
² Instituto de Astrofísica e Ciência do Espaço, Universidade do Porto, Portugal
³ Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Portugal
⁴ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
⁵ SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
⁶ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁷ Departamento de Física, I3N, Universidade de Aveiro, Portugal
⁸ ASD, IMCCE-CNRS UMR8028, Observatoire de Paris, UPMC, France

e-mail: vadibekyan@astro.up.pt

Abstract

We used a large sample of FGK dwarf planet-hosting stars with stellar parameters derived in a homogeneous way from the SWEET-Cat database (Santos et al. 2013) to study the relation between stellar metallicity and position of planets in the period-mass diagram. Using this large sample we show that planets orbiting metal-poor stars have longer periods than those in metal-rich systems. This trend is valid for masses at least from ≈ 10 M_⊕ to ≈ 4 M_Jup. Moreover, Earth-like planets orbiting metal-rich stars always show shorter periods (≤20 days) than those orbiting metal-poor stars. However, in the short-period regime there are a similar number of planets orbiting metal-poor stars. Our results suggest that the planets in the P-M_P diagram are evolving differently because of a mechanism that operates over a wide range of planetary masses. This mechanism is stronger or weaker depending on the metallicity of the respective system. Most probably planets in metal-poor disks form farther out from their central star and/or they form later and do not have time to migrate as far as the planets in metal-rich systems.