Examinando por Autor "Schultheis M."
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Ítem A Perspective on the Milky Way Bulge Bar as Seen from the Neutron-capture Elements Cerium and Neodymium with APOGEE(Institute of Physics, 2024-04-01) Sales-Silva J.V.; Cunha K.; Smith V.V.; Daflon S.; Souto D.; Guerço R.; Queiroz A.; Chiappini C.; Hayes C.R.; Masseron T.; Hasselquist, Sten; Horta D.; Prantzos N.; Zoccali M.; Allende Prieto C.; Barbuy B.; Beaton R.; Bizyaev D.; Fernández-Trincado J.G.; Frinchaboy P.M.; Holtzman J.A.; Johnson J.A.; Jönsson, Henrik; Majewski S.R.; Minniti D.; Nidever D.L.; Schiavon R.P.; Schultheis M.; Sobeck J.; Stringfellow G.S.; Zasowski G.This study probes the chemical abundances of the neutron-capture elements cerium and neodymium in the inner Milky Way from an analysis of a sample of ∼2000 stars in the Galactic bulge bar spatially contained within ∣X Gal∣ < 5 kpc, ∣Y Gal∣ < 3.5 kpc, and ∣Z Gal∣ < 1 kpc, and spanning metallicities between −2.0 ≲ [Fe/H] ≲ +0.5. We classify the sample stars into low- or high-[Mg/Fe] populations and find that, in general, values of [Ce/Fe] and [Nd/Fe] increase as the metallicity decreases for the low- and high-[Mg/Fe] populations. Ce abundances show a more complex variation across the metallicity range of our bulge-bar sample when compared to Nd, with the r-process dominating the production of neutron-capture elements in the high-[Mg/Fe] population ([Ce/Nd] < 0.0). We find a spatial chemical dependence of Ce and Nd abundances for our sample of bulge-bar stars, with low- and high-[Mg/Fe] populations displaying a distinct abundance distribution. In the region close to the center of the MW, the low-[Mg/Fe] population is dominated by stars with low [Ce/Fe], [Ce/Mg], [Nd/Mg], [Nd/Fe], and [Ce/Nd] ratios. The low [Ce/Nd] ratio indicates a significant contribution in this central region from r-process yields for the low-[Mg/Fe] population. The chemical pattern of the most metal-poor stars in our sample suggests an early chemical enrichment of the bulge dominated by yields from core-collapse supernovae and r-process astrophysical sites, such as magnetorotational supernovae.Ítem Atypical Mg-poor Milky Way Field Stars with Globular Cluster Second-generation-like Chemical Patterns(Institute of Physics Publishing, 2017-09) Fernández-Trincado J.G.; Zamora O.; Garcia-Hernández D.A.; Souto, Diogo; Dell'Agli F.; Schiavon R.P.; Geisler D.; Tang B.; Villanova S.; Hasselquist, Sten; Mennickent R.E.; Cunha, Katia; Shetrone M.; Prieto, Carlos Allende; Vieira K.; Zasowski G.; Sobeck J.; Hayes C.R.; Majewski S.R.; Placco V.M.; Beers T.C.; Schleicher D.R.G.; Robin A.C.; Mészáros, Sz.; Masseron T.; Pérez, Ana E. Garcia; Anders F.; Meza A.; Alves-Brito A.; Carrera R.; Minniti D.; Lane R.R.; Fernández-Alvar E.; Moreno E.; Pichardo B.; Pérez-Villegas A.; Schultheis M.; Roman-Lopes A.; Fuentes C.E.; Nitschelm C.; Harding P.; Bizyaev D.; Pan K.; Oravetz D.; Simmons A.; Ivans, Inese; Blanco-Cuaresma S.; Hernández J.; Alonso-Garcia J.; Valenzuela O.; Chanamé J.We report the peculiar chemical abundance patterns of 11 atypical Milky Way (MW) field red giant stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE). These atypical giants exhibit strong Al and N enhancements accompanied by C and Mg depletions, strikingly similar to those observed in the so-called second-generation (SG) stars of globular clusters (GCs). Remarkably, we find low Mg abundances ([Mg/Fe] < 0.0) together with strong Al and N overabundances in the majority (5/7) of the metal-rich ([Fe/H] -1.0) sample stars, which is at odds with actual observations of SG stars in Galactic GCs of similar metallicities. This chemical pattern is unique and unprecedented among MW stars, posing urgent questions about its origin. These atypical stars could be former SG stars of dissolved GCs formed with intrinsically lower abundances of Mg and enriched Al (subsequently self-polluted by massive AGB stars) or the result of exotic binary systems. We speculate that the stars Mg-deficiency as well as the orbital properties suggest that they could have an extragalactic origin. This discovery should guide future dedicated spectroscopic searches of atypical stellar chemical patterns in our Galaxy, a fundamental step forward to understanding the Galactic formation and evolution. © 2017. The American Astronomical Society. All rights reserved.Ítem Baade's window and APOGEE: Metallicities, ages, and chemical abundances(2017-04) Schultheis M.; Rojas-Arriagada A.; García Pérez A.E.; Jönsson H.; Hayden M.; Nandakumar G.; Cunha K.; Allende Prieto C.; Holtzman J.A.; Beers T.C.; Bizyaev D.; Brinkmann J.; Carrera R.; Cohen R.E.; Geisler D.; Hearty F.R.; Fernandez-Tricado J.G.; Maraston C.; Minnitti D.; Nitschelm C.; Roman-Lopes A.; Schneider D.P.; Tang B.; Villanova S.; Zasowski G.; Majewski S.R.Context. Baade's window (BW) is one of the most observed Galactic bulge fields in terms of chemical abundances. Owing to its low and homogeneous interstellar absorption it is considered the perfect calibration field for Galactic bulge studies. Aims. In the era of large spectroscopic surveys, calibration fields such as BW are necessary for cross calibrating the stellar parameters and individual abundances of the APOGEE survey. Methods. We use the APOGEE BW stars to derive the metallicity distribution function (MDF) and individual abundances for α-and iron-peak elements of the APOGEE ASPCAP pipeline (DR13), as well as the age distribution for stars in BW. Results. We determine the MDF of APOGEE stars in BW and find a remarkable agreement with that of the Gaia-ESO survey (GES). Both exhibit a clear bimodal distribution. We also find that the Mg-metallicity planes of the two surveys agree well, except for the metal-rich part ([Fe/H] > 0.1), where APOGEE finds systematically higher Mg abundances with respect to the GES. The ages based on the [C/N] ratio reveal a bimodal age distribution, with a major old population at ~ 10 Gyr, with a decreasing tail towards younger stars. A comparison of stellar parameters determined by APOGEE and those determined by other sources reveals detectable systematic offsets, in particular for spectroscopic surface gravity estimates. In general, we find a good agreement between individual abundances of O, Na, Mg, Al, Si, K, Ca, Cr, Mn, Co, and Ni from APOGEE with that of literature values. Conclusions. We have shown that in general APOGEE data show a good agreement in terms of MDF and individual chemical abundances with respect to literature works. Using the [C/N] ratio we found a significant fraction of young stars in BW. © ESO, 2017.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 Milky Way bar and bulge revealed by APOGEE and Gaia EDR3(EDP Sciences, 2021-12-01) Queiroz A.B.A.; Chiappini C.; Perez-Villegas A.; Khalatyan A.; Anders F.; Barbuy B.; Santiago B.X.; Steinmetz M.; Cunha K.; Schultheis M.; Majewski S.R.; Minchev I.; Minniti D.; Beaton R.L.; Cohen R.E.; Da Costa L.N.; Fernández-Trincado J.G.; Garcia-Hernández D.A.; Geisler D.; Hasselquist S.; Lane R.R.; Nitschelm C.; Rojas-Arriagada A.; Roman-Lopes A.; Smith V.; Zasowski G.We investigate the inner regions of the Milky Way using data from APOGEE and Gaia EDR3. Our inner Galactic sample has more than 26 500 stars within |XGal|< 5 kpc, |YGal|< 3.5 kpc, |ZGal|< 1 kpc, and we also carry out the analysis for a foreground-cleaned subsample of 8000 stars that is more representative of the bulge-bar populations. These samples allow us to build chemo-dynamical maps of the stellar populations with vastly improved detail. The inner Galaxy shows an apparent chemical bimodality in key abundance ratios [α/Fe], [C/N], and [Mn/O], which probe different enrichment timescales, suggesting a star formation gap (quenching) between the high- and low-α populations. Using a joint analysis of the distributions of kinematics, metallicities, mean orbital radius, and chemical abundances, we can characterize the different populations coexisting in the innermost regions of the Galaxy for the first time. The chemo-kinematic data dissected on an eccentricity-|Z|max plane reveal the chemical and kinematic signatures of the bar, the thin inner disc, and an inner thick disc, and a broad metallicity population with large velocity dispersion indicative of a pressure-supported component. The interplay between these different populations is mapped onto the different metallicity distributions seen in the eccentricity-|Z|max diagram consistently with the mean orbital radius and Vφ distributions. A clear metallicity gradient as a function of |Z|max is also found, which is consistent with the spatial overlapping of different populations. Additionally, we find and chemically and kinematically characterize a group of counter-rotating stars that could be the result of a gas-rich merger event or just the result of clumpy star formation during the earliest phases of the early disc that migrated into the bulge. Finally, based on 6D information, we assign stars a probability value of being on a bar orbit and find that most of the stars with large bar orbit probabilities come from the innermost 3 kpc, with a broad dispersion of metallicity. Even stars with a high probability of belonging to the bar show chemical bimodality in the [α/Fe] versus [Fe/H] diagram. This suggests bar trapping to be an efficient mechanism, explaining why stars on bar orbits do not show a significant, distinct chemical abundance ratio signature.