CNO behaviour in planet-harbouring stars. II. Carbon abundances in stars with and without planets using the CH band

Suárez-Andrés, L.; Israelian, G.; González Hernández, J. I.; Adibekyan, V. Zh.; Delgado Mena, E.; Santos, N. C.; Sousa, S. G.
Bibliographical reference

Astronomy and Astrophysics, Volume 599, id.A96, 9 pp.

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3
2017
Number of authors
7
IAC number of authors
3
Citations
41
Refereed citations
35
Description
Context. Carbon, oxygen and nitrogen (CNO) are key elements in stellar formation and evolution, and their abundances should also have a significant impact on planetary formation and evolution. Aims: We aim to present a detailed spectroscopic analysis of 1110 solar-type stars, 143 of which are known to have planetary companions. We have determined the carbon abundances of these stars and investigate a possible connection between C and the presence of planetary companions. Methods: We used the HARPS spectrograph to obtain high-resolution optical spectra of our targets. Spectral synthesis of the CH band at 4300 Å was performed with the spectral synthesis codes MOOG and FITTING. Results: We have studied carbon in several reliable spectral windows and have obtained abundances and distributions that show that planet host stars are carbon rich when compared to single stars, a signature caused by the known metal-rich nature of stars with planets. We find no different behaviour when separating the stars by the mass of the planetary companion Conclusions: We conclude that reliable carbon abundances can be derived for solar-type stars from the CH band at 4300 Å. We confirm two different slope trends for [C/Fe] with [Fe/H] because the behaviour is opposite for stars above and below solar values. We observe a flat distribution of the [C/Fe] ratio for all planetary masses, a finding that apparently excludes any clear connection between the [C/Fe] abundance ratio and planetary mass. Based on observations collected at the La Silla Paranal Observatory, ESO (Chile) with the HARPS spectrograph at the 3.6-m telescope (ESO runs ID 72.C-0488, 082.C-0212, and 085.C-0063).Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A96
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Observational Tests of the Processes of Nucleosynthesis in the Universe

Several spectroscopic analyses of stars with planets have recently been carried out. One of the most remarkable results is that planet-harbouring stars are on average more metal-rich than solar-type disc stars. Two main explanations have been suggested to link this metallicity excess with the presence of planets. The first of these, the “self

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