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

TL;DR

This paper derives precise, homogeneous spectroscopic parameters for 37 bright northern hemisphere stars with planets, improving the accuracy of stellar and planetary mass estimates and highlighting caution for evolved stars.

Contribution

It provides a new set of homogeneous stellar parameters for bright planet host stars using high-resolution spectra and standard analysis methods, included in the SWEET-Cat catalogue.

Findings

Spectroscopic parameters are consistent with existing databases for most stars.

Evolved stars show significant discrepancies in derived parameters.

Planetary mass estimates can vary up to 100% depending on stellar mass accuracy.

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.