Browsing by Author "Zoccali, Manuela"
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- Item3D kinematics through the X-shaped Milky Way bulge(2013) Vásquez Godoy, Sergio Osmán.; Zoccali, Manuela; Baffico Haramoto, Rodolfo Maurizio; Minniti, D.
- ItemA Homogeneous Set of Globular Cluster Relative Distances and Reddenings(2005) Recio-Blanco a; Zoccali, Manuela
- ItemA search for substructures near the Galactic plane and bulge using RR Lyrae stars as tracers(2024) Cristi Cambiaso, Nicolas Eduardo; Catelan, Marcio; Zoccali, Manuela; Pontificia Universidad Catolica de Chile. Faculty of Physics. Institute of AstrophysicsUsando estrellas pulsantes de tipo RR Lyrae, hacemos una búsqueda de subestructuras Galácticas ("stellar streams" y cúmulos globulares) en la región del plano Galáctico. Construimos una muestra de estrellas RR Lyrae con valores de distancia y metalicidades. Estudiamos esta muestra con un algoritmo de "clustering" para encontrar grupos de estrellas cercanas y con propiedades similares. Mediante esta búsqueda, recuperamos estructuras conocidas y encontramos posibles nuevas estructuras.
- ItemA spectroscopic survey of thick disc stars outside the solar neighbourhood(2011) Kordopatis, G.; Zoccali, Manuela
- ItemA transiting planet among 23 new near-threshold candidates from the OGLE survey - OGLE-TR-182(2008) Pont, F.; Minniti, D.; Ramírez Alegría, Sebastián A.; Zoccali, Manuela
- ItemAbundances in the Galactic bulge(2008) Barbuy, B.; Zoccali, Manuela; Minniti, D.; Barbuy, B.; Zoccali, Manuela; Minniti, D.
- ItemAbundances of disk and bulge giants from high-resolution optical spectra II. O, Mg, Ca, and Ti in the bulge sample (vol 598, A101, 2017)(2017) Jonsson, H.; Ryde, N.; Schultheis, M.; Zoccali, Manuela
- ItemAbundances of disk and bulge giants from high-resolution optical spectra II. O, Mg, Co, and Ti in the bulge sample(2017) Jönsson, H.; Ryde, N.; Schultheis, M.; Zoccali, Manuela
- ItemAbundances of iron-peak elements in 58 bulge spheroid stars from APOGEE(EDP SCIENCES S A, 2024) Barbuy, B.; Friaca, A. C. S.; Ernandes, H.; da Silva, P.; Souza, S. O.; Fernandez-Trincado, J. G.; Cunha, K.; Smith, V. V.; Masseron, T.; Perez-Villegas, A.; Chiappini, C.; Queiroz, A. B. A.; Santiago, B. X.; Beers, T. C.; Anders, F.; Schiavon, R. P.; Valentini, M.; Minniti, D.; Geisler, D.; Souto, D.; Placco, V. M.; Zoccali, Manuela; Feltzing, S.; Schultheis, M.; Nitschelm, C.Context. Stars presently identified in the bulge spheroid are probably very old, and their abundances can be interpreted as due to the fast chemical enrichment of the early Galactic bulge. The abundances of the iron-peak elements are important tracers of nucleosynthesis processes, in particular oxygen burning, silicon burning, the weak s-process, and alpha-rich freeze-out. Aims. The aim of this work is to derive the abundances of V, Cr, Mn, Co, Ni, and Cu in 58 bulge spheroid stars and to compare them with the results of a previous analysis of data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Methods. We selected the best lines for V, Cr, Mn, Co, Ni, and Cu located within the H-band of the spectrum, identifying the most suitable ones for abundance determination, and discarding severe blends. Using the stellar physical parameters available for our sample from the DR17 release of the APOGEE project, we derived the individual abundances through spectrum synthesis. We then complemented these measurements with similar results from different bulge field and globular cluster stars, in order to define the trends of the individual elements and compare with the results of chemical-evolution models. Results. We verify that the H-band has useful lines for the derivation of the elements V, Cr, Mn, Co, Ni, and Cu in moderately metal-poor stars. The abundances, plotted together with others from high-resolution spectroscopy of bulge stars, indicate that: V, Cr, and Ni vary in lockstep with Fe; Co tends to vary in lockstep with Fe, but could be showing a slight decrease with decreasing metallicity; and Mn and Cu decrease with decreasing metallicity. These behaviours are well reproduced by chemical-evolution models that adopt literature yields, except for Cu, which appears to drop faster than the models predict for [Fe/H]<-0.8. Finally, abundance indicators combined with kinematical and dynamical criteria appear to show that our 58 sample stars are likely to have originated in situ.
- ItemAlpha element abundances and gradients in the Milky Way bulge from FLAMES-GIRAFFE spectra of 650 K giants(2011) Gonzalez, O.; Zoccali, Manuela; Minniti, D.
- ItemAssembling a high-precision abundance catalogue of solar twins in GALAH for phylogenetic studies(2024) Walsen, Kurt; Jofre, Paula; Buder, Sven; Yaxley, Keaghan; Das, Payel; Yates, Robert M.; Hua, Xia; Signor, Theosamuele; Eldridge, Camilla; Rojas-Arriagada, Alvaro; Tissera, Patricia B.; Johnston, Evelyn; Aguilera-Gomez, Claudia; Zoccali, Manuela; Gilmore, Gerry; Foley, RobertStellar chemical abundances have proved themselves a key source of information for understanding the evolution of the Milky Way, and the scale of major stellar surveys such as GALAH have massively increased the amount of chemical data available. However, progress is hampered by the level of precision in chemical abundance data as well as the visualization methods for comparing the multidimensional outputs of chemical evolution models to stellar abundance data. Machine learning methods have greatly improved the former; while the application of tree-building or phylogenetic methods borrowed from biology are beginning to show promise with the latter. Here, we analyse a sample of GALAH solar twins to address these issues. We apply The Cannon algorithm to generate a catalogue of about 40 000 solar twins with 14 high precision abundances which we use to perform a phylogenetic analysis on a selection of stars that have two different ranges of eccentricities. From our analyses, we are able to find a group with mostly stars on circular orbits and some old stars with eccentric orbits whose age-[Y/Mg] relation agrees remarkably well with the chemical clocks published by previous high precision abundance studies. Our results show the power of combining survey data with machine learning and phylogenetics to reconstruct the history of the Milky Way.
- ItemC and N abundances of main sequence and subgiant branch stars in NGC 1851(2012) Lardo, C.; Zoccali, Manuela
- ItemCalcium triplet metallicity calibration for stars in the Galactic bulge(2015) Vasquez, S.; Zoccali, Manuela; Hill, V.; Gonzalez, O. A.; Saviane, I.; Rejkuba, M.; Battaglia, G.
- ItemCharacterization of the VVV Survey RR Lyrae Population across the Southern Galactic Plane(2017) Minniti, D.; Dekany, Istvan; Majaess, Daniel; Palma, Tali; Pullen, Joyce; Rejkuba, Marina; Alonso-García, Javier; Catelan, Márcio; Hempel, Maren; Zoccali, Manuela; Contreras Ramos, Rodrigo Andrés; Gonzalez, Oscar A.; Irwin, Mike; Lucas, Philip W.; Saito, Roberto K.; Tissera, Patricia; Valenti, Elena
- ItemChemical abundances in giant stars of newly discovered infrared globular clusters 2MASS GC02 and Mercer 5(Asociación Argentina de Astronomía, 2011) Peñaloza, F.; Vásquez, S.; Kurtev, R.; Borissova, J.; Pessev, P.; Zoccali, ManuelaPresentamos un estudio de abundacias de dos cúmulos globulares escondidos, Mercer5 y 2MASSGC02, utilizando espectros (IR) de alta resolución. Medimos precisas velocidades radiales de vr = +194 ± 0.3kms−1 para Mercer5 estrella 1 y vr = +177 ± 0.3kms−1 para Mercer5 estrella 2. Encontramos [Fe/H] = −1.00 ± 0.02dex y un realce en el promedio de α −elementos de ≈ +0.40 ± 0.02dex para Mercer5, mientras que para 2MASS GC02 sólo hacemos un análisis cualitativo, debido a su insuficiente señal/ruido.
- ItemChemical abundances of 11 bulge stars from high-resolution, near-IR spectra(2010) Ryde, N.; Minniti, D.; Zoccali, Manuela
- ItemChemical Abundances of the Highly Obscured Galactic Globular Clusters 2MASS GC02 and Mercer 5(2015) Vásquez Godoy, Sergio Osmán.; Zoccali, Manuela
- ItemChemical evolution of fluorine in the bulge High-resolution K-band spectra of giants in three fields(2014) Jonsson, H.; Ryde, N.; Harper, G.; Cunha, K.; Schultheis, M.; Eriksson, K.; Kobayashi, C.; Smith, V.; Zoccali, Manuela
- ItemChemically Dissected Rotation Curves of the Galactic Bulge from Main-sequence Proper Motions(2018) Clarkson, William I.; Calamida, Annalisa; Sahu, Kailash C.; Brown, Thomas M.; Gennaro, Mario; Avila, Roberto J.; Valenti, Jeff; Debattista, Victor P.; Rich, R. Michael; Minniti, D.; Zoccali, Manuela; Aufdemberge, Emily R.
- ItemCobalt and copper abundances in 56 Galactic bulge red giants(2020) Ernandes, H.; Barbuy, B.; Friaca, A. C. S.; Hill, V.; Zoccali, Manuela; Minniti, D.; Renzini, A.; Ortolani, S.