Spectroscopic parameters for 451 stars in the HARPS GTO planet search program

Abstract

To understand the formation and evolution of solar-type stars in the solar neighborhood, we need to measure their stellar parameters to high accuracy. We present a catalogue of accurate stellar parameters for 451 stars that represent the HARPS Guaranteed Time Observations (GTO) "high precision" sample. Spectroscopic stellar parameters were measured using high signal-to-noise (S /N) spectra acquired with the HARPS spectrograph. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and the recent ARES code for measuring line equivalent widths. We show that our results agree well with those ones presented in the literature (for stars in common). We present a useful calibration for the effective temperature as a function of the index color B − V and [Fe/H]. We use our results to study the metallicity-planet correlation, namely for very low mass planets. The results presented here suggest that in contrast to their jovian couterparts, neptune-like planets do not form preferentially around metal-rich stars. The ratio of jupiter-to-neptunes is also an increasing function of stellar metallicity. These results are discussed in the context of the core-accretion model for planet formation.

Chemical abundances of 451 stars from the HARPS GTO planet search program

“…This sub-sample consists of 451 stars, selected from the volume-limited sample of solar neighbourhood stars studied with the CORALIE spectrograph (Udry et al 2000) as well as a group of planet hosts from the southern hemisphere. Details about this sample are given in Sousa et al (2008). We note that we updated the original GTO catalogue using data from the extrasolar planets encyclopaedia 1 , to take account of the newly discovered planets orbiting the stars HD 40307 , HD 47186, and HD 181433 (Bouchy et al in prep.).…”

“…The stellar parameters used in the present paper were determined by Sousa et al (2008). We refer to this paper for details.…”

“…A grid of Kurucz (1993) ATLAS9 atmospheres were used as input, along with the equivalent widths and the atomic parameters, wavelength (λ), excitation energy of the lower energy level (χ l ), and oscillator strength (log g f ) of each line. The atmospheric parameters, effective temperature (T eff ), surface gravity (log g), microturbulence (ξ t ), and metallicity ([Fe/H]) were taken from Sousa et al (2008) and derived from the same spectra used in our study. This provided consistency to our work, ensuring that it was more uniform and less affected by external errors.…”

“…Full Tables 1 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/497/563 at lower [Fe/H] values (Udry et al 2006;Sousa et al 2008). However, there are still an insufficient number of planets for compiling a robust statistical distribution.…”

“…This sample contains 451 stars, of which 68 are planet hosts and the remaining 383 stars are dwarfs with no known orbiting planets (Sousa et al 2008). We also derive the kinematical properties of the sample.…”