Examinando por Autor "De Laverny P."
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Ítem Atomic data for the Gaia-ESO Survey(EDP Sciences, 2021-01-01) Heiter U.; Lind K.; Bergemann M.; Asplund M.; Mikolaitis Š.; Barklem P. S.; Masseron T.; De Laverny P.; Magrini L.; Edvardsson B.; Jönsson H.; Pickering J. C.; Ryde N.; Bayo Arán A.; Bensby T.; Casey A. R.; Feltzing S.; Jofré P.; Korn A. J.; Pancino E.; Damiani F.; Lanzafame A.; Lardo C.; Monaco L.; Morbidelli L.; Smiljanic R.; Worley C.; Zaggia S.; Randich S.; Gilmore G.F.Context. We describe the atomic and molecular data that were used for the abundance analyses of FGK-type stars carried out within the Gaia-ESO Public Spectroscopic Survey in the years 2012 to 2019. The Gaia-ESO Survey is one among several current and future stellar spectroscopic surveys producing abundances for Milky-Way stars on an industrial scale. Aims. We present an unprecedented effort to create a homogeneous common line list, which was used by several abundance analysis groups using different radiative transfer codes to calculate synthetic spectra and equivalent widths. The atomic data are accompanied by quality indicators and detailed references to the sources. The atomic and molecular data are made publicly available at the CDS. Methods. In general, experimental transition probabilities were preferred but theoretical values were also used. Astrophysical gf-values were avoided due to the model-dependence of such a procedure. For elements whose lines are significantly affected by a hyperfine structure or isotopic splitting, a concerted effort has been made to collate the necessary data for the individual line components. Synthetic stellar spectra calculated for the Sun and Arcturus were used to assess the blending properties of the lines. We also performed adetailed investigation of available data for line broadening due to collisions with neutral hydrogen atoms. Results. Among a subset of over 1300 lines of 35 elements in the wavelength ranges from 475 to 685 nm and from 850 to 895 nm, we identified about 200 lines of 24 species which have accurate gf-values and are free of blends in the spectra of the Sun and Arcturus. For the broadening due to collisions with neutral hydrogen, we recommend data based on Anstee-Barklem-O'Mara theory, where possible. We recommend avoiding lines of neutral species for which these are not available. Theoretical broadening data by R.L. Kurucz should be used for Sc II, Ti II, and Y II lines; additionally, for ionised rare-earth species, the Unsöld approximation with an enhancement factor of 1.5 for the line width can be used. Conclusions. The line list has proven to be a useful tool for abundance determinations based on the spectra obtained within the Gaia-ESO Survey, as well as other spectroscopic projects. Accuracies below 0.2 dex are regularly achieved, where part of the uncertainties are due to differences in the employed analysis methods. Desirable improvements in atomic data were identified for a number of species, most importantly Al I, S I, and Cr II, but also Na I, Si I, Ca II, and Ni I.Ítem Gaia focused product release : asteroid orbital solution: properties and assessmen(EDP Sciences, 2023-12) David P.; Mignard F.; Hestroffer D.; Tanga P.; Spoto F.; Berthier J.; Pauwels T.; Roux W.; Barbier A.; Cellino A.; Carry B.; Delbo M.; Dell'oro A.; Fouron C.; Galluccio L.; Klioner S.A.; Mary N.; Muinonen K.; Ordenovic C.; Oreshina-Slezak I.; Panem C.; Petit J.-M.; Portell J.; Brown A.G.A; Thuillot W.; Vallenari A.; Prusti T.; De Bruijne J.H.J.; Arenou F.; Babusiaux C.; Biermann M.; Creevey O.L.; Ducourant C.; Evans D.W.; Eyer L.; Guerra R.; Hutton A.; Jordi C.; Lammers U.; Lindegren L.; Luri X.; Randich S.; Sartoretti P.; Smiljanic R.; Walton N.A.; Bailer-Jones C.A.L.; Bastian U.; Cropper M.; Drimmel R.; Katz D.; Soubiran C.; Van Leeuwen F.; Audard M.; Bakker J.; Blomme R.; Castañeda J.; De Angeli F.; Fabricius C.; Fouesneau M; Frémat Y.; Guerrier A.; Masana E.; Messineo R.; Nicolas C.; Nienartowicz K.; Pailler F.; Panuzzo P.; Riclet F.; Seabroke G.M.; Sordo R.; Thévenin F.; Gracia-Abril G.; Teyssier D.; Altmann M.; Benson K.; Burgess P.W.; Busonero D.; Busso G.; Cánovas H.; Cheek N.; Clementini G.; Damerdji Y.; Davidson M.; De Teodoro P.; Delchambre L.; Fraile Garcia E.; Garabato D.; García-Lario P.; Garralda Torres N.; Gavras P.; Haigron R.; Hambly N.C.; Harrison D.L.; Hatzidimitriou D.; Hernández J.; Hodgkin S.T.; Holl B.; Jamal S.; Jordan S.; Krone-Martins A.; Lanzafame A.C.; Löffler W.; Lorca A.; Marchal O.; Marrese P.M.; Moitinho A.; Nuñez Campos M.; Osborne P.; Pancino E.; Recio-Blanco A.; Riello M.; Rimoldini L.; Robin A.C.; Roegiers T.; Sarro L.M.; Schultheis M.; Siopis C.; Smith M.; Sozzetti A.; Utrilla E.; Van Leeuwen M.; Weingrill K.; Abbas U.; Ábrahám P.; Abreu Aramburu A.; Aerts C.; Altavilla G.; Álvarez M.A.; Alves J.; Anderson R.I.; Antoja T.; Baines D.; Baker S.G.; Balog Z.; Barache C.; Barbato D.; Barros M.; Barstow M.A.; Bartolomé S.; Bashi D.; Bauchet N.; Baudeau N.; Becciani U.; Bedin L.R.; Bellas-Velidis I.; Bellazzini M.; Beordo W.; Berihuete A.; Bernet M.; Bertolotto C.; Bertone S.; Bianchi L.; Binnenfeld A.; Blazere A.; Boch T.; Bombrun A.; Bouquillon S.; Bragaglia A.; Braine J.; Bramante L.; Breedt E.; Bressan A.; Brouillet N.; Brugaletta E.; Bucciarelli B.; Butkevich A.G.; Buzzi R.; Caffau E.; Cancelliere R.; Cannizzo S.; Carballo R.; Carlucci T.; Carnerero M.I.; Carrasco J.M.; Carretero J.; Carton S.; Casamiquela L.; Castellani M.; Castro-Ginard A.; Cesare V.; Charlot P.; Chemin L.; Chiaramida V.; Chiavassa A.; Chornay N.; Collins R.; Contursi G.; Cooper W.J.; Cornez T.; Crosta M.; Crowley C.; Dafonte C.; De Laverny P.; De Luise F.; De March R.; De Souza R.; De Torres A.; Del Peloso E.F.; Delgado A.; Dharmawardena T.E.; Diakite S.; Diener C.; Distefano E.; Dolding C.; Dsilva K.; Durán J.; Enke H.; Esquej P.; Fabre C.; Fabrizio M.; Faigler S.; Fatović M.; Fedorets G.; Fernández-Hernández J.; Fernique P.; Figueras F.; Fournier Y.; Gai M.; Galinier M.; Garcia-Gutierrez A.; García-Torres M.; Garofalo A.; Gerlach E; Geyer R.; Giacobbe P.; Gilmore G.; Girona S.; Giuffrida G.; Gomel R.; Gomez A.; González-Núñez J.; González-Santamaría I.; Gosset E.; Granvik M.; Gregori Barrera V.; Gutiérrez-Sánchez R.; Haywood M.; Helmer A.; Helmi A.; Henares K.; Hidalgo S.L.; Hilger T.; Hobbs D.; Hottier C.; Huckle H.E.; Jabłońska M.; Jansen F.; Jiménez-Arranz Ó.; Juaristi Campillo J.; Khanna S.; Kordopatis G.; Kóspál Á.; Kostrzewa-Rutkowska Z.; Kun M.; Lambert S.; Lanza A.F.; Le Campion J.-F.; Lebreton Y.; Lebzelter T.; Leccia S.; Lecoeur-Taibi I.; Lecoutre G.; Liao S.; Liberato L.; Licata E.; Lindstrøm H.E.P.; Lister T.A.; Livanou E.; Lobel A.; Loup C.; Mahy L.; Mann R.G.; Manteiga M.; Marchant J.M.; Marconi M.; Marín Pina D.; Marinoni S.; Marshall D.J.; Martín Lozano J.; Martín-Fleitas J.M.; Marton G.; Masip A.; Massari D.; Mastrobuono-Battisti A.; Mazeh T.; McMillan P.J.; Meichsner J.; Messina S.; Michalik D.; Millar N.R.; Mints A.; Molina D.; Molinaro R.; Molnár L.; Monari G.; Monguió M.; Montegriffo P.; Montero A.; Mor R.; Mora A.; Morbidelli R.; Morel T.; Morris D.; Mowlavi N.; Munoz D.; Muraveva T.; Murphy C.P.; Musella I.; Nagy Z.; Nieto S.; Noval L.; Ogden A.; Pagani C.; Pagano I.; Palaversa L.; Palicio P.A.; Pallas-Quintela L.; Panahi A.; Payne-Wardenaar S.; Pegoraro L.; Penttilä A.; Pesciullesi P.; Piersimoni A.M.; Pinamonti M.; Pineau F.-X.; Plachy E.; Plum G.; Poggio E.; Pourbaix D.; Prša A.; Pulone L.; Racero E.; Rainer M.; Raiteri C.M.; Ramos P.; Ramos-Lerate M.; Ratajczak M.; Re Fiorentin P.; Regibo S.; Reylé C.; Ripepi V.; Riva A.; Rix H.-W.; Rixon G.; Robichon N.; Robin C.; Romero-Gómez M.; Rowell N.; Royer F.; Ruz Mieres D.; Rybicki K.A.; Sadowski G.; Sáez Núñez A.; Sagristà Sellés A.; Sahlmann J.; Sanchez Gimenez V.; Sanna N.; Santoveña R.; Sarasso M.; Sarrate Riera C.; Sciacca E.; Segovia J.C.; Ségransan D.; Shahaf S.; Siebert A.; Siltala L.; Slezak E.; Smart R.L.; Snaith O.N.; Solano E.; Solitro F.; Souami D.; Souchay J.; Spina L.; Spitoni E.; Squillante L.A.; Steele I.A.; Steidelmüller H.; Surdej J.; Szabados L.; Taris F.; Taylor M.B.; Teixeira R.; Tisanić K.; Tolomei L.; Torra F.; Torralba Elipe G.; Trabucchi M.; Tsantaki M.; Ulla A.; Unger N.; Vanel O.; Vecchiato A.; Vicente D.; Voutsinas S.; Weiler M.; Wyrzykowski Ł.; Zhao H.; Zorec J.; Zwitter T.; Balaguer-Núñez L.; Leclerc N.; Morgenthaler S.; Robert G.; Zucker S.Context. We report the exploitation of a sample of Solar System observations based on data from the third Gaia Data Release (Gaia DR3) of nearly 157 000 asteroids. It extends the epoch astrometric solution over the time coverage planned for the Gaia DR4, which is not expected before the end of 2025. This data set covers more than one full orbital period for the vast majority of these asteroids. The orbital solutions are derived from the Gaia data alone over a relatively short arc compared to the observation history of many of these asteroids. Aims. The work aims to produce orbital elements for a large set of asteroids based on 66 months of accurate astrometry provided by Gaia and to assess the accuracy of these orbital solutions with a comparison to the best available orbits derived from independent observations. A second validation is performed with accurate occultation timings. Methods. We processed the raw astrometric measurements of Gaia to obtain astrometric positions of moving objects with 1D sub-mas accuracy at the bright end. For each asteroid that we matched to the data, an orbit fitting was attempted in the form of the best fit of the initial conditions at the median epoch. The force model included Newtonian and relativistic accelerations to derive the observation equations, which were solved with a linear least-squares fit. Results. Orbits are provided in the form of state vectors in the International Celestial Reference Frame for 156 764 asteroids, including near-Earth objects, main-belt asteroids, and Trojans. For the asteroids with the best observations, the (formal) relative uncertainty σa/a is better than 10-10. Results are compared to orbits available from the Jet Propulsion Laboratory and MPC. Their orbits are based on much longer data arcs, but from positions of lower quality. The relative differences in semi-major axes have a mean of 5 × 10-10 and a scatter of 5 × 10-9 © The Authors 2023.Ítem The Gaia -ESO Survey: Exploring the complex nature and origins of the Galactic bulge populations(EDP Sciences, 2017-05) Rojas-Arriagada A.; Recio-Blanco A.; De Laverny P.; Mikolaitis Š.; Matteucci F.; Spitoni E.; Schultheis M.; Hayden M.; Hill V.; Zoccali M.; Minniti D.; Gonzalez O.A.; Gilmore G.; Randich S.; Feltzing S.; Alfaro E.J.; Babusiaux C.; Bensby T.; Bragaglia A.; Flaccomio E.; Koposov S.E.; Pancino E.; Bayo A.; Carraro G.; Casey A.R.; Costado M.T.; Damiani F.; Donati P.; Franciosini E.; Hourihane A.; Jofré P.; Lardo C.; Lewis J.; Lind K.; Magrini L.; Morbidelli L.; Sacco G.G.; Worley C.C.; Zaggia S.Context. As observational evidence steadily accumulates, the nature of the Galactic bulge has proven to be rather complex: the structural, kinematic, and chemical analyses often lead to contradictory conclusions. The nature of the metal-rich bulge - and especially of the metal-poor bulge - and their relation with other Galactic components, still need to be firmly defined on the basis of statistically significant high-quality data samples. Aims. We used the fourth internal data release of the Gaia-ESO survey to characterize the bulge metallicity distribution function (MDF), magnesium abundance, spatial distribution, and correlation of these properties with kinematics. Moreover, the homogeneous sampling of the different Galactic populations provided by the Gaia-ESO survey allowed us to perform a comparison between the bulge, thin disk, and thick disk sequences in the [Mg/Fe] vs. [Fe/H] plane in order to constrain the extent of their eventual chemical similarities. Methods. We obtained spectroscopic data for ∼2500 red clump stars in 11 bulge fields, sampling the area -10° ≥ l ≥ +8° and -10° ≥ b ≥ -4° from the fourth internal data release of the Gaia-ESO survey. A sample of ∼6300 disk stars was also selected for comparison. Spectrophotometric distances computed via isochrone fitting allowed us to define a sample of stars likely located in the bulge region. Results. From a Gaussian mixture models (GMM) analysis, the bulge MDF is confirmed to be bimodal across the whole sampled area. The relative ratio between the two modes of the MDF changes as a function of b, with metal-poor stars dominating at high latitudes. The metal-rich stars exhibit bar-like kinematics and display a bimodality in their magnitude distribution, a feature which is tightly associated with the X-shape bulge. They overlap with the metal-rich end of the thin disk sequence in the [Mg/Fe] vs. [Fe/H] plane. On the other hand, metal-poor bulge stars have a more isotropic hot kinematics and do not participate in the X-shape bulge. Their Mg enhancement level and general shape in the [Mg/Fe] vs. [Fe/H] plane is comparable to that of the thick disk sequence. The position at which [Mg/Fe] starts to decrease with [Fe/H], called the "knee", is observed in the metal-poor bulge at [Fe/H]knee = -0:37 ± 0:09, being 0.06 dex higher than that of the thick disk. Although this difference is inside the error bars, it suggest a higher star formation rate (SFR) for the bulge than for the thick disk. We estimate an upper limit for this difference of Δ[Fe/H]knee = 0:24 dex. Finally, we present a chemical evolution model that suitably fits the whole bulge sequence by assuming a fast (<1 Gyr) intense burst of stellar formation that takes place at early epochs. Conclusions.We associate metal-rich stars with the bar boxy/peanut bulge formed as the product of secular evolution of the early thin disk. On the other hand, the metal-poor subpopulation might be the product of an early prompt dissipative collapse dominated by massive stars. Nevertheless, our results do not allow us to firmly rule out the possibility that these stars come from the secular evolution of the early thick disk. This is the first time that an analysis of the bulge MDF and α-abundances has been performed in a large area on the basis of a homogeneous, fully spectroscopic analysis of high-resolution, high S/N data. © ESO 2017.Ítem The Gaia -ESO Survey: The origin and evolution of s -process elements(EDP Sciences, 2018-09) Magrini L.; Spina L.; Randich S.; Friel E.; Kordopatis G.; Worley C.; Pancino E.; Bragaglia A.; Donati P.; Tautvaišienė G.; Bagdonas V.; Delgado-Mena E.; Adibekyan V.; Sousa S.G.; Jiménez-Esteban F.M.; Sanna N.; Roccatagliata V.; Bonito R.; Sbordone L.; Duffau S.; Gilmore G.; Feltzing S.; Jeffries R.D.; Vallenari A.; Alfaro E.J.; Bensby T.; Francois P.; Koposov S.; Korn A.J.; Recio-Blanco A.; Smiljanic R.; Bayo A.; Carraro G.; Casey A.R.; Costado M.T.; Damiani F.; Franciosini E.; Frasca A.; Hourihane A.; Jofré P.; De Laverny P.; Lewis J.; Masseron T.; Monaco L.; Morbidelli L.; Prisinzano L.; Sacco G.; Zaggia S.Context. Several works have found an increase of the abundances of the s-process neutron-capture elements in the youngest Galactic stellar populations. These trends provide important constraints on stellar and Galactic evolution and they need to be confirmed with large and statistically significant samples of stars spanning wide age and distance intervals. Aims. We aim to trace the abundance patterns and the time evolution of five s-process elements - two belonging to the first peak, Y and Zr, and three belonging to the second peak, Ba, La, and Ce - using the Gaia-ESO IDR5 results for open clusters and disc stars. Methods. From the UVES spectra of cluster member stars, we determined the average composition of clusters with ages >0.1 Gyr. We derived statistical ages and distances of field stars, and we separated them into thin and thick disc populations. We studied the time-evolution and dependence on metallicity of abundance ratios using open clusters and field stars whose parameters and abundances were derived in a homogeneous way. Results. Using our large and homogeneous sample of open clusters, thin and thick disc stars, spanning an age range larger than 10 Gyr, we confirm an increase towards young ages of s-process abundances in the solar neighbourhood. These trends are well defined for open clusters and stars located nearby the solar position and they may be explained by a late enrichment due to significant contribution to the production of these elements from long-living low-mass stars. At the same time, we find a strong dependence of the s-process abundance ratios on the Galactocentric distance and on the metallicity of the clusters and field stars. Conclusions. Our results, derived from the largest and most homogeneous sample of s-process abundances in the literature, confirm the growth with decreasing stellar ages of the s-process abundances in both field and open cluster stars. At the same time, taking advantage of the abundances of open clusters located in a wide Galactocentric range, these results offer a new perspective on the dependence of the s-process evolution on the metallicity and star formation history, pointing to different behaviours at various Galactocentric distances. © 2018 ESO.Ítem The Gaia-ESO Survey: Churning through the Milky Way(EDP Sciences, 2018-01) Hayden M.R.; Recio-Blanco A.; De Laverny P.; Mikolaitis S.; Guiglion G.; Randich S.; Bayo A.; Bensby T.; Bergemann M.; Bragaglia A.; Casey A.; Costado M.; Feltzing S.; Franciosini E.; Hourihane A.; Jofre P.; Koposov S.; Kordopatis G.; Lanzafame A.; Lardo C.; Lewis J.; Lind K.; Magrini L.; Monaco L.; Morbidelli L.; Pancino E.; Sacco G.; Stonkute E.; Worley C.C.; Zwitter T.; Hill V.; Gilmore G.Context. There have been conflicting results with respect to the extent that radial migration has played in the evolution of the Galaxy. Additionally, observations of the solar neighborhood have shown evidence of a merger in the past history of the Milky Way that drives enhanced radial migration. Aims. We attempt to determine the relative fraction of stars that have undergone significant radial migration by studying the orbital properties of metal-rich ([Fe/H] > 0.1) stars within 2 kpc of the Sun. We also aim to investigate the kinematic properties, such as velocity dispersion and orbital parameters, of stellar populations near the Sun as a function of [Mg/Fe] and [Fe/H], which could show evidence of a major merger in the past history of the Milky Way. Methods. We used a sample of more than 3000 stars selected from the fourth internal data release of the Gaia-ESO Survey. We used the stellar parameters from the Gaia-ESO Survey along with proper motions from PPMXL to determine distances, kinematics, and orbital properties for these stars to analyze the chemodynamic properties of stellar populations near the Sun. Results. Analyzing the kinematics of the most metal-rich stars ([Fe/H] > 0.1), we find that more than half have small eccentricities (e< 0.2) or are on nearly circular orbits. Slightly more than 20% of the metal-rich stars have perigalacticons Rp> 7 kpc. We find that the highest [Mg/Fe], metal-poor populations have lower vertical and radial velocity dispersions compared to lower [Mg/Fe] populations of similar metallicity by ~10 km s-1. The median eccentricity increases linearly with [Mg/Fe] across all metallicities, while the perigalacticon decreases with increasing [Mg/Fe] for all metallicities. Finally, the most [Mg/Fe]-rich stars are found to have significant asymmetric drift and rotate more than 40 km s-1 slower than stars with lower [Mg/Fe] ratios. Conclusions. While our results cannot constrain how far stars have migrated, we propose that migration processes are likely to have played an important role in the evolution of the Milky Way, with metal-rich stars migrating from the inner disk toward to solar neighborhood and past mergers potentially driving enhanced migration of older stellar populations in the disk. © ESO, 2018.Ítem The Gaia-ESO Survey: Low-α element stars in the Galactic bulge(EDP Sciences, 2017-07) Recio-Blanco A.; Rojas-Arriagada A.; De Laverny P.; Mikolaitis S.; Hill V.; Zoccali M.; Fernández-Trincado J.G.; Robin A.C.; Babusiaux C.; Gilmore G.; Randich S.; Alfaro E.; Allende Prieto C.; Bragaglia A.; Carraro G.; Jofré P.; Lardo C.; Monaco L.; Morbidelli L.; Zaggia S.We take advantage of the Gaia-ESO Survey iDR4 bulge data to search for abundance anomalies that could shed light on the composite nature of the Milky Way bulge. The α-element (Mg, Si, and whenever available, Ca) abundances, and their trends with Fe abundances have been analysed for a total of 776 bulge stars. In addition, the aluminum abundances and their ratio to Fe and Mg have also been examined. Our analysis reveals the existence of low-α element abundance stars with respect to the standard bulge sequence in the [α/ Fe] versus [Fe/H] plane. Eighteen objects present deviations in [α/ Fe] ranging from 2.1 to 5.3σ with respect to the median standard value. Those stars do not show Mg-Al anti-correlation patterns. Incidentally, this sign of the existence of multiple stellar populations is reported firmly for the first time for the bulge globular cluster NGC 6522. The identified low-α abundance stars have chemical patterns that are compatible with those of the thin disc. Their link with massive dwarf galaxies accretion seems unlikely, as larger deviations in α abundance and Al would be expected. The vision of a bulge composite nature and a complex formation process is reinforced by our results. The approach used, which is a multi-method and model-driven analysis of high resolution data, seems crucial to reveal this complexity. © ESO, 2017.