Research Note

Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere ^⋆

The impact on stellar and planetary mass

¹ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
e-mail: sousasag@astro.up.pt
² Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
³ SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
⁴ Instituto de Astrofísica de Canarias, 38200, La Laguna, Tenerife, Spain
⁵ Departamento de Astrofísica, Universidade de La Laguna, 38205, La Laguna, Tenerife, Spain
⁶ Departamento de Física, Universidade Federal do Rio Grande do Norte, Brazil

Received: 27 October 2014
Accepted: 19 February 2015

Abstract

Aims. In this work we derive new precise and homogeneous parameters for 37 stars with planets. For this purpose, we analyze high resolution spectra obtained by the NARVAL spectrograph for a sample composed of bright planet host stars in the northern hemisphere. The new parameters are included in the SWEET-Cat online catalogue.

Methods. To ensure that the catalogue is homogeneous, we use our standard spectroscopic analysis procedure, ARES+MOOG, to derive effective temperatures, surface gravities, and metallicities. These spectroscopic stellar parameters are then used as input to compute the stellar mass and radius, which are fundamental for the derivation of the planetary mass and radius.

Results. We show that the spectroscopic parameters, masses, and radii are generally in good agreement with the values available in online databases of exoplanets. There are some exceptions, especially for the evolved stars. These are analyzed in detail focusing on the effect of the stellar mass on the derived planetary mass.

Conclusions. We conclude that the stellar mass estimations for giant stars should be managed with extreme caution when using them to compute the planetary masses. We report examples within this sample where the differences in planetary mass can be as high as 100% in the most extreme cases.