Da Silva, R.Danielski, C.Delgado Mena, E.Magrini, L.Turrini, D.Biazzo, K.Tsantaki, M.Rainer, M.Helminiak, K. G.Benatti, S.Adibekyan, V.Sanna, N.Sousa, S.Casali, G.Van Der Swaelmen, M.2025-05-232025-05-230004-6361http://www.scopus.com/inward/record.url?scp=85202041051&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733752442Context. One of the ultimate goals of the ESA Ariel space mission is to shed light on the formation pathways and evolution of planetary systems in the Solar neighbourhood. Stellar elemental abundances are the cipher key to decode planetary compositional signatures. This makes it imperative to perform a large chemical survey not only of the planets, but their host stars as well. Aims. This work is aimed at providing homogeneous chemical abundances for C, N, and O among a sample of 181 stars belonging to Tier 1 of the Ariel mission candidate sample. Methods. We applied the spectral synthesis and equivalent width methods to a variety of atomic and molecular indicators (C I lines at 5052 and 5380.3 Å, [O I] forbidden line at 6300.3 Å, C2 bands at 5128 and 5165 Å, and CN band at 4215 Å) using high-resolution and high signal-to-noise spectra collected with a range of spectrographs. Results. We determined carbon abundances for 180 stars, nitrogen abundances for 105 stars, and oxygen abundances for 89 stars. We analysed the results in the light of the Galactic chemical evolution and in terms of the planetary companion properties. We find that our sample essentially follows standard trends with respect to the metallicity values expected for the [C/Fe], [N/Fe], and [O/Fe] abundance ratios. The proportion between carbon and oxygen abundances (both yields of primary production) is consistent with a constant ratio as [O/H] increases. Meanwhile, the abundance of nitrogen tends to increase with the increasing of the oxygen abundance, supporting the theoretical assumption of a secondary production of nitrogen. The [C/N], [C/O], and [N/O] abundance ratios are also correlated with [Fe/H], which might introduce biases in the interpretation of the planetary compositions and formation histories when host stars of different metallicities are compared. Finally, we provide relations that can be used to qualitatively estimate whether the atmospheric composition of planets is enriched (or otherwise) with respect to the host stars.We thank the reviewer for their positive words and constructive suggestions concerning an earlier version of the present paper, which improved its content and readability. This work has been developed within the framework of the Ariel stellar Characterisation working group of the ESA Ariel space mission Consortium. The team is very grateful to the service astronomers that performed our observations at ESO (with UVES during P105 and P106), with the TNG (using HARPS-N during A41 and A42), with the LBT (using PEPSI during 2021 and 2022), and at the SAAO (with SALT during 2023). This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna. We acknowledge financial support from the ASI-INAF agreement no. 2022- 14-HH.0. E.D.M. acknowledges the support from Fundacao para a Ciencia e a Tecnologia (FCT) through national funds and from FEDER through COMPETE2020 by the following grants: UIDB/04434/2020 and UIDP/04434/2020 and 2022.04416.PTDC. E.D.M. further acknowledges the support from FCT through Stimulus FCT contract 2021.01294.CEECIND. C.D. acknowledges financial support from the INAF initiative IAF Astronomy Fellowships in Italy, grant name GExoLife. Polish participation in SALT is funded by MEiN grant No. 2021/WK/01. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: Istituto Nazionale di Astrofisica, Italy; The University of Arizona on behalf of the Arizona Board of Regents; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, representing OSU, University of Notre Dame, University of Minnesota and University of Virginia. The TNG is operated by the Fundacion Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain). Some of the observations reported in this paper were obtained with the Southern African Large Telescope (SALT). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. We thank the reviewer for their positive words and constructive suggestions concerning an earlier version of the present paper, which improved its content and readability. This work has been developed within the framework of the Ariel \u2018stellar Characterisation\u2019 working group of the ESA Ariel space mission Consortium. The team is very grateful to the service astronomers that performed our observations at ESO (with UVES during P105 and P106), with the TNG (using HARPS-N during A41 and A42), with the LBT (using PEPSI during 2021 and 2022), and at the SAAO (with SALT during 2023). This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna. We acknowledge financial support from the ASI-INAF agreement no. 2022-14-HH.0. E.D.M. acknowledges the support from Funda\u00E7\u00E3o para a Ci\u00EAncia e a Tecnologia (FCT) through national funds and from FEDER through COM-PETE2020 by the following grants: UIDB/04434/2020 & UIDP/04434/2020 and 2022.04416.PTDC. E.D.M. further acknowledges the support from FCT through Stimulus FCT contract 2021.01294.CEECIND. C.D. acknowledges financial support from the INAF initiative \u201CIAF Astronomy Fellowships in Italy\u201D, grant name GExoLife. Polish participation in SALT is funded by MEiN grant No. 2021/WK/01. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: Istituto Nazionale di Astrofisica, Italy; The University of Arizona on behalf of the Arizona Board of Regents; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, representing OSU, University of Notre Dame, University of Minnesota and University of Virginia. The TNG is operated by the Fundaci\u00F3n Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain). Some of the observations reported in this paper were obtained with the Southern African Large Telescope (SALT). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.enPublisher Copyright: © The Authors 2024.Galaxy: diskGalaxy: evolutionPlanetary systemsPlanets and satellites: compositionSolar neighborhoodStars: abundances2024-08-0110.1051/0004-6361/20245060485202041051