CNO behaviour in planet-harbouring stars

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

doi:10.1051/0004-6361/201628455

Cited by 34 publications

(30 citation statements)

References 56 publications

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“…For those stars with T eff < 4800 K we find a steep decrease in [C/Fe] abundance ratios with temperature. A similar effect can also be found for other α-elements (Adibekyan et al 2012b), as well as for nitrogen (Suárez-Andrés et al 2016).…”

Section: Carbon Abundancessupporting

confidence: 75%

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CNO behaviour in planet-harbouring stars

Suárez-Andrés

Israelian

Hernández

et al. 2017

A&A

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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.

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Section: Carbon Abundancessupporting

confidence: 75%

“…Rotational broadening was set as a free parameter with v sin i varying between 0.0 and 14.0 km s −1 with a step of 1 km s −1 . For more information about the procedure followed, see Suárez-Andrés et al (2016). In Fig.…”

Section: Ch Bandmentioning

confidence: 99%

CNO behaviour in planet-harbouring stars

Suárez-Andrés

Israelian

Hernández

et al. 2017

A&A

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“…The total sample is composed by 136 stars with planets and 975 stars without detected planets. Chemical abundances of these samples for refractory elements with A < 29 can be found in Adibekyan et al (2012) together with oxygen (Bertran de Lis et al 2015), carbon (Suárez-Andrés et al 2016b), lithium and nitrogen abundances (Suárez-Andrés et al 2016a, only for a small fraction of stars).…”

Section: Observations and Stellar Parametersmentioning

confidence: 98%

Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program

Delgado-Mena

Tsantaki²,

Adibekyan

et al. 2017

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155

104

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Aims. To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. The aim of this work is to explore the chemical abundances of neutron capture elements which are a product of different nucleosynthesis processes taking place at diverse objects in the Galaxy, such as massive stars, asymptotic giant branch (AGB) stars and supernovae (SNe) explosions. Methods. We derive chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu for a large sample of more than 1000 FGK dwarf stars with high-resolution (R ∼ 115000) and high-quality spectra from the HARPS-GTO program. The abundances are derived by a standard Local Thermodinamyc Equilibrium (LTE) analysis using measured Equivalent Widths (EWs) injected to the code MOOG and a grid of Kurucz ATLAS9 atmospheres. Results. We find that thick disk stars are chemically disjunct for Zn and Eu and also show on average higher Zr but lower Ba and Y when compared to the thin disk stars. We also discovered that the previously identified high-α metal-rich population is also enhanced in Cu, Zn, Nd and Eu with respect to the thin disk but presents Ba and Y abundances lower on average, following the trend of thick disk stars towards higher metallities and further supporting the different chemical composition of this population. By making a qualitative comparison of O (pure α), Mg, Eu (pure r-process) and s-process elements we can distinguish between the contribution of the more massive stars (SNe II for α and r-process elements) and the lower mass stars (AGBs) whose contribution to the enrichment of the Galaxy is delayed due to their longer lifetimes. The ratio of heavy-s to light-s elements of thin disk stars presents the expected behaviour (increasing towards lower metallicities) and can be explained by a major contribution of low-mass AGB stars for s-process production at disk metallicities. However, the opposite trend found for thick disk stars suggests that intermediate-mass AGB stars played an important role in the enrichment of the gas from where these stars formed. Previous works in the literature also point to a possible primary production of light-s elements at low metallicities to explain this trend. Finally, we also find an enhancement of light-s elements in the thin disk at super solar metallicities which could be caused by the contribution of metal-rich AGB stars.

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“…Carbon, nitrogen, and oxygen are among the most abundant elements in the Universe (Asplund et al, 2009). They are crucial for several astrophysical fields, including, e.g., the formation of planetary systems and astrobiology (e.g., Lodders and Fegley, 2002;Suárez-Andrés et al, 2016), stellar structure and evolution (e.g., Salaris and Cassisi, 2005;Busso et al, 2007;Charbonnel and Zahn, 2007;Lattanzio et al, 2015;Lagarde et al, 2019), stellar nucleosynthesis (e.g., van den Hoek and Groenewegen, 1997;Meynet and Maeder, 2002), and Galactic chemical evolution (e.g., Chiappini et al, 2003;Vincenzo et al, 2016). However, their origins are still debated and the role in their production in stars with different masses, metallicities, and rotational velocities is still not definitively settled.…”

Section: Introductionmentioning

confidence: 99%

Light Elements in the Universe

Randich

Magrini

2021

Front. Astron. Space Sci.

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Due to their production sites, as well as to how they are processed and destroyed in stars, the light elements are excellent tools to investigate a number of crucial issues in modern astrophysics: from stellar structure and non-standard processes at work in stellar interiors to age dating of stars; from pre-main sequence evolution to the star formation histories of young clusters and associations and to multiple populations in globular clusters; from Big Bang nucleosynthesis to the formation and chemical enrichment history of the Milky Way Galaxy and its populations, just to cite some relevant examples. In this paper, we focus on lithium, beryllium, and boron (LiBeB) and on carbon, nitrogen, and oxygen (CNO). LiBeB are rare elements, with negligible abundances with respect to hydrogen; on the contrary, CNO are among the most abundant elements in the Universe, after H and He. Pioneering observations of light-element surface abundances in stars started almost 70 years ago and huge progress has been achieved since then. Indeed, for different reasons, precise measurements of LiBeB and CNO are difficult, even in our Sun; however, the advent of state-of-the-art ground- and space-based instrumentation has allowed the determination of high-quality abundances in stars of different type, belonging to different Galactic populations, from metal-poor halo stars to young stars in the solar vicinity and from massive stars to cool dwarfs and giants. Noticeably, the recent large spectroscopic surveys performed with multifiber spectrographs have yielded detailed and homogeneous information on the abundances of Li and CNO for statistically significant samples of stars; this has allowed us to obtain new results and insights and, at the same time, raise new questions and challenges. A complete understanding of the light-element patterns and evolution in the Universe has not been still achieved. Perspectives for further progress will open up soon thanks to the new generation instrumentation that is under development and will come online in the coming years.

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CNO behaviour in planet-harbouring stars

Cited by 34 publications

References 56 publications

CNO behaviour in planet-harbouring stars

CNO behaviour in planet-harbouring stars

Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program

Light Elements in the Universe

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