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Centro de Astrofísica da Universidade do Porto

Metallicity of M dwarfs
III. Planet-metallicity and planet-stellar mass correlations of the HARPS GTO M dwarf sample

V. Neves, X. Bonfils, N. C. Santos, X. Delfosse, T. Forveille, F. Allard, S. Udry

Abstract
Aims. The aim of this work is the study of the planet-metallicity and the planet-stellar mass correlations for M dwarfs from the HARPS GTO M dwarf subsample.
Methods. We use a new method that takes advantage of the HARPS high-resolution spectra to increase the precision of metallicity, using previous photometric calibrations of [Fe/H] and effective temperature as starting values.
Results. In this work we use our new calibration (rms = 0.08 dex) to study the planet-metallicity relation of our sample. The wellknown correlation for giant planet FGKM hosts with metallicity is present. Regarding Neptunians and smaller hosts no correlation is found but there is a hint that an anti-correlation with [Fe/H] may exist. We combined our sample with the California Planet Survey late-K and M-type dwarf sample to increase our statistics but found no new trends. We fitted a power law to the frequency histogram of the Jovian hosts for our sample and for the combined sample, ƒp = C10α[Fe/H], using two different approaches: a direct bin fitting and a Bayesian fitting procedure. We obtained a value for C between 0.02 and 0.04 and for α between 1.26 and 2.94.
Regarding stellar mass, an hypothetical correlation with planets was discovered, but was found to be the result of a detection bias.

Keywords
stars: fundamental parameters – stars: late-type – stars: low-mass – stars: atmospheres – planetary systems

Notes
Based on observations made with the HARPS instrument on the ESO 3.6-m telescope at La Silla Observatory under programme ID 072.C-0488.
Tables 2, 8, and Appendix A are available in electronic form at http://www.aanda.org

Astronomy and Astrophysics
Volume 551, Page A36_1
March 2013

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