Examinando por Autor "Zwitter, T."
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Ítem Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines(EDP SCIENCES, 2016-06) Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maíz Apellániz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.Aims. We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods. We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s-1) gas emission. Results. We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These “shells” are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum.Ítem The Gaia -ESO Survey: Double-, triple-, and quadruple-line spectroscopic binary candidates(EDP Sciences, 2017-12) Merle, T.; Van Eck, S.; Jorissen, A.; Van Der Swaelmen, M.; Masseron, T.; Zwitter, T.; Hatzidimitriou, D.; Klutsch, A.; Pourbaix, D.; Blomme, R.; Worley, C.C.; Sacco, G.; Lewis, J.; Abia, C.; Traven, G.; Sordo, R.; Bragaglia, A.; Smiljanic, R.; Pancino, E.; Damiani, F.; Hourihane, A.; Gilmore, G.; Randich, S.; Koposov, S.; Casey, A.; Morbidelli, L.; Franciosini, E.; Magrini, L.; Jofre, P.; Costado, M.T.; Jeffries, R.D.; Bergemann, M.; Lanzafame, A.C.; Bayo, A.; Carraro, G.; Flaccomio, E.; Monaco, L.; Zaggia, S.Context. The Gaia-ESO Survey (GES) is a large spectroscopic survey that provides a unique opportunity to study the distribution of spectroscopic multiple systems among different populations of the Galaxy. Aims. Our aim is to detect binarity/multiplicity for stars targeted by the GES from the analysis of the cross-correlation functions (CCFs) of the GES spectra with spectral templates. Methods. We developed a method based on the computation of the CCF successive derivatives to detect multiple peaks and determine their radial velocities, even when the peaks are strongly blended. The parameters of the detection of extrema (doe) code have been optimized for each GES GIRAFFE and UVES setup to maximize detection. The doe code therefore allows to automatically detect multiple line spectroscopic binaries (SBn, n ≥ 2). Results. We apply this method on the fourth GES internal data release and detect 354 SBn candidates (342 SB2, 11 SB3, and even one SB4), including only nine SBs known in the literature. This implies that about 98% of these SBn candidates are new because of their faint visual magnitude that can reach V = 19. Visual inspection of the SBn candidate spectra reveals that the most probable candidates have indeed a composite spectrum. Among the SB2 candidates, an orbital solution could be computed for two previously unknown binaries: CNAME 06404608+0949173 (known as V642 Mon) in NGC 2264 and CNAME 19013257-0027338 in Berkeley 81 (Be 81). A detailed analysis of the unique SB4 (four peaks in the CCF) reveals that CNAME 08414659-5303449 (HD 74438) in the open cluster IC 2391 is a physically bound stellar quadruple system. The SB candidates belonging to stellar clusters are reviewed in detail to discard false detections. We suggest that atmospheric parameters should not be used for these system components; SB-specific pipelines should be used instead. Conclusions. Our implementation of an automatic detection of spectroscopic binaries within the GES has allowed the efficient discovery of many new multiple systems. With the detection of the SB1 candidates that will be the subject of a forthcoming paper, the study of the statistical and physical properties of the spectroscopic multiple systems will soon be possible for the entire GES sample. © ESO 2017.Ítem The Gaia -ESO Survey: Double-, triple-, and quadruple-line spectroscopic binary candidates(EDP Sciences, 2017) Merle, T.; Van Eck, S.; Jorissen, A.; Van Der Swaelmen, M.; Masseron, T.; Zwitter, T.; Hatzidimitriou, D.; Klutsch, A.; Pourbaix, D.; Blomme, R.; Worley, C.C.; Sacco, G.; Lewis, J.; Abia, C.; Traven, G.; Sordo, R.; Bragaglia, A.; Smiljanic, R.; Pancino, E.; Damiani, F.; Hourihane, A.; Gilmore, G.; Randich, S.; Koposov, S.; Casey, A.; Morbidelli, L.; Franciosini, E.; Magrini, L.; Jofre, P.; Costado, M.T.; Jeffries, R.D.; Bergemann, M.; Lanzafame, A.C.; Bayo, A.; Carraro, G.; Flaccomio, E.; Monaco, L.; Zaggia, S.Context. The Gaia-ESO Survey (GES) is a large spectroscopic survey that provides a unique opportunity to study the distribution of spectroscopic multiple systems among different populations of the Galaxy. Aims. Our aim is to detect binarity/multiplicity for stars targeted by the GES from the analysis of the cross-correlation functions (CCFs) of the GES spectra with spectral templates. Methods. We developed a method based on the computation of the CCF successive derivatives to detect multiple peaks and determine their radial velocities, even when the peaks are strongly blended. The parameters of the detection of extrema (doe) code have been optimized for each GES GIRAFFE and UVES setup to maximize detection. The doe code therefore allows to automatically detect multiple line spectroscopic binaries (SBn, n ≥ 2). Results. We apply this method on the fourth GES internal data release and detect 354 SBn candidates (342 SB2, 11 SB3, and even one SB4), including only nine SBs known in the literature. This implies that about 98% of these SBn candidates are new because of their faint visual magnitude that can reach V = 19. Visual inspection of the SBn candidate spectra reveals that the most probable candidates have indeed a composite spectrum. Among the SB2 candidates, an orbital solution could be computed for two previously unknown binaries: CNAME 06404608+0949173 (known as V642 Mon) in NGC 2264 and CNAME 19013257-0027338 in Berkeley 81 (Be 81). A detailed analysis of the unique SB4 (four peaks in the CCF) reveals that CNAME 08414659-5303449 (HD 74438) in the open cluster IC 2391 is a physically bound stellar quadruple system. The SB candidates belonging to stellar clusters are reviewed in detail to discard false detections. We suggest that atmospheric parameters should not be used for these system components; SB-specific pipelines should be used instead. Conclusions. Our implementation of an automatic detection of spectroscopic binaries within the GES has allowed the efficient discovery of many new multiple systems. With the detection of the SB1 candidates that will be the subject of a forthcoming paper, the study of the statistical and physical properties of the spectroscopic multiple systems will soon be possible for the entire GES sample.Ítem The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy(EDP Sciences, 2022-10-01) Randich, S.; Gilmore, G.; Magrini, L.; Sacco, G.G.; Jackson, R.J.; Jeffries, R.D.; Worley, C.C.; Hourihane, A.; Gonneau, A.; Viscasillas Vázquez, C.; Franciosini, E.; Lewis, J.R.; Alfaro, E.J.; Allende Prieto, C.; Bensby, T.; Blomme, R.; Bragaglia, A.; Flaccomio, E.; François, P.; Irwin, M.J.; Koposov, S.E.; Korn, A.J.; Lanzafame, A.C.; Pancino, E.; Recio Blanco, A.; Smiljanic, R.; Van Eck, S.; Zwitter, T.; Asplund, M.; Bonifacio, P.; Feltzing, S.; Binney, J.; Drew, J.; Ferguson, A.M.N.; Micela, G.; Negueruela, I.; Prusti, T.; Rix, H.-W.; Vallenari, A.; Bayo, A.; Bergemann, M.; Biazzo, K.; Carraro, G.; Casey, A.R.; Damiani, F.; Frasca, A.; Heiter, U.; Hill, V.; Jofré, P.; de Laverny, P.; Lind, K.; Marconi, G.; Martayan, C.; Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sbordone, L.; Sousa, S.G.; Zaggia, S.; Adibekyan, V.; Bonito, R.; Caffau, E.; Daflon, S.; Feuillet, D.K.; Gebran, M.; González Hernández, J.I.; Guiglion, G.; Herrero, A.; Lobel, A.; Maíz Apellániz, J.; Merle, T.; Mikolaitis, S.; Montes, D.; Morel, T.; Soubiran, C.; Spina, L.; Tabernero, H.M.; Tautvaišiene, G.; Traven, G.; Valentini, M.; Van der Swaelmen, M.; Villanova, S.; Wright, N.J.; Abbas, U.; Aguirre Børsen-Koch, V.; Alves, J.; Balaguer Núnez, L.; Barklem, P.S.; Barrado, D.; Berlanas, S.R.; Binks, A.S.; Bressan, A.; Capuzzo Dolcetta, R.; Casagrande, L.; Casamiquela, L.; Collins, R.S.; D’Orazi, V.; Dantas, M.L.L.; Debattista, V.P.; Delgado Mena, E.; Di Marcantonio, P.; Drazdauskas, A.; Evans, N.W.; Famaey, B.; Franchini, M.; Frémat, Y.; Friel, E.D.; Fu, X.; Geisler, D.; Gerhard, O.; González Solares, E.A.; Grebel, E.K.; Gutiérrez Albarrán, M.L.; Hatzidimitriou, D.; Held, E.V.; Jiménez Esteban, F.; Jönsson, H.; Jordi, C.; Khachaturyants, T.; Kordopatis, G.; Kos, J.; Lagarde, N.; Mahy, L.; Mapelli, M.; Marfil, E.; Martell, S.L.; Messina, S.; Miglio, A.; Minchev, I.; Moitinho, A.; Montalban, J.; Monteiro, M.J.P.F.G.; Morossi, C.; Mowlavi, N.; Mucciarelli, A.; Murphy, D.N.A.; Nardetto, N.; Ortolani, S.; Paletou, F.; Palous, J.; Paunzen, E.; Pickering, J.C.; Quirrenbach, A.; Re Fiorentin, P.; Read, J.I.; Romano, D.; Ryde, N.; Sanna, N.; Santos, W.; Seabroke, G.M.; Spagna, A.; Steinmetz, M.; Stonkuté, E.; Sutorius, E.; Thévenin, F.; Tosi, M.; Tsantaki, M.; Vink, J.S.; Wright, N.; Wyse, R.F.G.; Zoccali, M.; Zorec, J.; Zucker, D.B.; Walton, N.A.Context. In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with the general aim of delivering stellar parameters and elemental abundances for large samples of Galactic stars, complementing Gaia astrometry. Among those surveys, the Gaia-ESO Public Spectroscopic Survey, the only one performed on a 8m class telescope, was designed to target 100 000 stars using FLAMES on the ESO VLT (both Giraffe and UVES spectrographs), covering all the Milky Way populations, with a special focus on open star clusters. Aims. This article provides an overview of the survey implementation (observations, data quality, analysis and its success, data products, and releases), of the open cluster survey, of the science results and potential, and of the survey legacy. A companion article reviews the overall survey motivation, strategy, Giraffe pipeline data reduction, organisation, and workflow. Methods. We made use of the information recorded and archived in the observing blocks; during the observing runs; in a number of relevant documents; in the spectra and master catalogue of spectra; in the parameters delivered by the analysis nodes and the working groups; in the final catalogue; and in the science papers. Based on these sources, we critically analyse and discuss the output and products of the Survey, including science highlights. We also determined the average metallicities of the open clusters observed as science targets and of a sample of clusters whose spectra were retrieved from the ESO archive. Results. The Gaia-ESO Survey has determined homogeneous good-quality radial velocities and stellar parameters for a large fraction of its more than 110 000 unique target stars. Elemental abundances were derived for up to 31 elements for targets observed with UVES. Lithium abundances are delivered for about 1/3 of the sample. The analysis and homogenisation strategies have proven to be successful; several science topics have been addressed by the Gaia-ESO consortium and the community, with many highlight results achieved. Conclusions. The final catalogue will be released through the ESO archive in the first half of 2022, including the complete set of advanced data products. In addition to these results, the Gaia-ESO Survey will leave a very important legacy, for several aspects and for many years to come. © ESO 2022.Ítem The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products?(EDP Sciences, 2022-10-01) Gilmore, G.; Randich, S.; Worley, C.C.; Hourihane, A.; Gonneau, A.; Sacco, G.G.; Lewis, J.R.; Magrini, L.; François, P.; Jeffries, R.D.; Koposov, S.E.; Bragaglia, A.; Alfaro, E.J.; Allende Prieto, C.; Blomme, R.; Korn, A.J.; Lanzafame, A.C.; Pancino, E.; Recio Blanco, A.; Smiljanic, R.; Van Eck, S.; Zwitter, T.; Bensby, T.; Flaccomio, E.; Irwin, M.J.; Franciosini, E.; Morbidelli, L.; Damiani, F.; Bonito, R.; Friel, E.D.; Vink, J.S.; Prisinzano, L.; Abbas, U.; Hatzidimitriou, D.; Held, E.V.; Jordi, C.; Paunzen, E.; Spagna, A.; Jackson, R.J.; Maíz Apellániz, J.; Asplund, M.; Bonifacio, P.; Feltzing, S.; Binney, J.; Drew, J.; Ferguson, A.M.N.; Micela, G.; Negueruela, I.; Prusti, T.; Rix, H.-W.; Vallenari, A.; Bergemann, M.; Casey, A.R.; Laverny, P.; Frasca, A.; Hill, V.; Lind, K.; Sbordone, L.; Sousa, S.G.; Adibekyan, V.; Caffau, E.; Daflon, S.; Feuillet, D.K.; Gebran, M.; González Hernández, J.I.; Guiglion, G.; Herrero, A.; Lobel, A.; Merle, T.; Mikolaitis, S.; Montes, D.; Morel, T.; Ruchti, G.; Soubiran, C.; Tabernero, H.M.; Tautvaišiene, G.; Traven, G.; Valentini, M.; Van der Swaelmen, M.; Villanova, S.; Viscasillas Vázquez, C.; Bayo, A.; Biazzo, K.; Carraro, G.; Edvardsson, B.; Heiter, U.; Jofré, P.; Marconi, G.; Martayan, C.; Masseron, T.; Monaco, L.; Walton, N.A.; Zaggia, S.; Aguirre Børsen-Koch, V.; Alves, J.; Balaguer Núnez, L.; Barklem, P.S.; Barrado, D.; Bellazzini, M.; Berlanas, S.R.; Binks, A.S.; Bressan, A.; Capuzzo Dolcetta, R.; Casagrande, L.; Casamiquela, L.; Collins, R.S.; D’Orazi, V.; Dantas, M.L.L.; Debattista, V.P.; Delgado Mena, E.; Marcantonio, P. Di; Drazdauskas, A.; Evans, N.W.; Famaey, B.; Franchini, M.; Frémat, Y.; Fu, X.; Geisler, D.; Gerhard, O.; González Solares, E.A.; Grebel, E.K.; Albarrán Gutiérrez, M.L.; Jiménez Esteban, F.; Jönsson, H.; Khachaturyants, T.; Kordopatis, G.; Kos, J.; Lagarde, N.; Ludwig, H.-G.; Mahy, L.; Mapelli, M.; Marfil, E.; Martell, S.L.; Messina, S.; Miglio, A.; Minchev, I.; Moitinho, A.; Montalban, J.; Monteiro, M.J.P.F.G.; Morossi, C.; Mowlavi, N.; Mucciarelli, A.; Murphy, D.N.A.; Nardetto, N.; Ortolani, S.; Paletou, F.; Palous, J.; Pickering, J.C.; Quirrenbach, A.; Re Fiorentin, P.; Read, J.I.; Romano, D.; Ryde, N.; Sanna, N.; Santos, W.; Seabroke, G.M.; Spina, L.; Steinmetz, M.; Stonkuté, E.; Sutorius, E.; Thévenin, F.; Tosi, M.; Tsantaki, M.; Wright, N.; Wyse, R.F.G.; Zoccali, M.; Zorec, J.; Zucker, D.B.Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars and star clusters, extending across a very wide range of abundances and ages. This provides a legacy data set of intrinsic value, and equally a large wide-ranging dataset that is of value for the homogenisation of other and future stellar surveys and Gaia’s astrophysical parameters. Aims. This article provides an overview of the survey methodology, the scientific aims, and the implementation, including a description of the data processing for the GIRAFFE spectra. A companion paper introduces the survey results. Methods. Gaia-ESO aspires to quantify both random and systematic contributions to measurement uncertainties. Thus, all available spectroscopic analysis techniques are utilised, each spectrum being analysed by up to several different analysis pipelines, with considerable effort being made to homogenise and calibrate the resulting parameters. We describe here the sequence of activities up to delivery of processed data products to the ESO Science Archive Facility for open use. Results. The Gaia-ESO Survey obtained 202 000 spectra of 115 000 stars using 340 allocated VLT nights between December 2011 and January 2018 from GIRAFFE and UVES. Conclusions. The full consistently reduced final data set of spectra was released through the ESO Science Archive Facility in late 2020, with the full astrophysical parameters sets following in 2022. A companion article reviews the survey implementation, scientific highlights, the open cluster survey, and data products. © G. Gilmore et al. 2022.Ítem The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr?(EDP Sciences, 2016-05) Bouvier, J.; Lanzafame, A.C.; Venuti, L.; Klutsch, A.; Jeffries, R.; Frasca, A.; Moraux, E.; Biazzo, K.; Messina, S.; Micela, G.; Randich, S.; Stauffer, J.; Cody, A.M.; Flaccomio, E.; Gilmore, G.; Bayo, A.; Bensby, T.; Bragaglia, A.; Carraro, G.; Casey, A.; Costado, M.T.; Damiani, F.; Delgado Mena, E.; Donati, P.; Franciosini, E.; Hourihane, A.; Koposov, S.; Lardo, C.; Lewis, J.; Magrini, L.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sacco, G.; Sbordone, L.; Sousa, S.G.; Vallenari, A.; Worley, C.C.; Zaggia, S.; Zwitter, T.Context. The evolution of lithium abundance in cool dwarfs provides a unique probe of nonstandard processes in stellar evolution. Aims. We investigate the lithium content of young low-mass stars in the 5 Myr old, star forming region NGC 2264 and its relationship with rotation. Methods. We combine lithium equivalent width measurements (EW(Li)) from the Gaia-ESO Survey with the determination of rotational periods from the CSI 2264 survey. We only consider bona fide nonaccreting cluster members to minimize the uncertainties on EW(Li). Results. We report the existence of a relationship between lithium content and rotation in NGC 2264 at an age of 5 Myr. The Li-rotation connec tion is seen over a restricted temperature range (Teff = 3800–4400 K), where fast rotators are Li-rich compared to slow rotators. This correlation is similar to, albeit of lower amplitude than, the Li-rotation connection previously reported for K dwarfs in the 125 Myr old Pleiades cluster. We investigate whether the nonstandard pre-main-sequence models developed so far to explain the Pleiades results, which are based on episodic accre tion, pre-main-sequence, core-envelope decoupling, and/or radius inflation due to enhanced magnetic activity, can account for early development of the Li-rotation connection. While radius inflation appears to be the most promising possibility, each of these models has issues. We therefore also discuss external causes that might operate during the first few Myr of pre-main-sequence evolution, such as planet engulfment and/or steady disk accretion, as possible candidates for the common origin for Li excess and fast rotation in young low-mass pre-main-sequence stars. Conclusions. The emergence of a connection between lithium content and rotation rate at such an early age as 5 Myr suggests a complex link between accretion processes, early angular momentum evolution, and possibly planet formation, which likely impacts early stellar evolution and has yet to be fully deciphered.Ítem The Gaia-ESO Survey: revisiting the Li-rich giant problem(OXFORD UNIV PRESS, 2016-07) Casey, A. R.; Ruchti, G.; Masseron, T.; Randich, S.; Gilmore, G.; Lind, K.; Kennedy, G. M.; Koposov, S. E.; Hourihane, A.; Franciosini, E.; Lewis, J. R.; Magrini, L.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.; Feltzing, S.; Jeffries, R. D.; Vallenari, A.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Korn, A. J.; Lanzafame, A.; Pancino, E.; Recio-Blanco, A.; Smiljanic, R.; Carraro, G.; Costado, M. T.; Damiani, F.; Donati, P.; Frasca, A.; Jofre, P.; Lardo, C.; de Laverny, P.; Monaco, L.; Prisinzano, L.; Sbordone, L.; Sousa, S. G.; Tautvaisien, G.; Zaggia, S.; Zwitter, T.; Delgado Mena, E.; Chorniy, Y.; Martell, S. L.; Silva Aguirre, V.; Miglio, A.; Chiappini, C.; Montalban, J.; Morel, T.; Valentini, M.The discovery of lithium-rich giants contradicts expectations from canonical stellar evolution. Here we report on the serendipitous discovery of 20 Li-rich giants observed during the Gaia-ESO Survey, which includes the first nine Li-rich giant stars known towards the CoRoT fields. Most of our Li-rich giants have near-solar metallicities and stellar parameters consistent with being before the luminosity bump. This is difficult to reconcile with deep mixing models proposed to explain lithium enrichment, because these models can only operate at later evolutionary stages: at or past the luminosity bump. In an effort to shed light on the Li-rich phenomenon, we highlight recent evidence of the tidal destruction of close-in hot Jupiters at the sub-giant phase. We note that when coupled with models of planet accretion, the observed destruction of hot Jupiters actually predicts the existence of Li-rich giant stars, and suggests that Li-rich stars should be found early on the giant branch and occur more frequently with increasing metallicity. A comprehensive review of all known Li-rich giant stars reveals that this scenario is consistent with the data. However, more evolved or metal-poor stars are less likely to host close-in giant planets, implying that their Li-rich origin requires an alternative explanation, likely related to mixing scenarios rather than external phenomena.Ítem The Gaia-ESO Survey: the selection function of the Milky Way field stars(Royal Astronomical Society, 2016-04) Stonkutė, E.; Koposov, S. E.; Howes, L. M.; Feltzing, S.; Worley, C. C.; Gilmore, G.; Ruchti, G. R.; Kordopatis, G.; Randich, S.; Zwitter, T.; Bensby, T.; Bragaglia, A.; Smiljanic, R.; Costado, M. T.; Tautvaišienė, G.; Casey, A. R.; Korn, A. J.; Lanzafame, A. C.; Pancino, E.; Franciosini, E.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Magrini, L.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Sbordone, L.The Gaia-ESO Survey was designed to target all major Galactic components (i.e. bulge, thin and thick discs, halo and clusters), with the goal of constraining the chemical and dynamical evolution of the Milky Way. This paper presents the methodology and considerations that drive the selection of the targeted, allocated and successfully observed Milky Way field stars. The detailed understanding of the survey construction, specifically the influence of target selection criteria on observed Milky Way field stars is required in order to analyse and interpret the survey data correctly. We present the target selection process for the Milky Way field stars observed with Very Large Telescope/Fibre Large Array Multi Element Spectrograph and provide the weights that characterize the survey target selection. The weights can be used to account for the selection effects in the Gaia-ESO Survey data for scientific studies. We provide a couple of simple examples to highlight the necessity of including such information in studies of the stellar populations in the Milky Way.