26 results on '"Enrico Maiorca"'
Search Results
2. Design, Analysis and Selection of Haptic Inceptor Configurations for Tilt-Rotor Application
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Lorenzo Pollini, Chiara Cavaliere, Mario Innocenti, Heinrich Bulthoff, Harald Teufel, Luca Mozzillo, Marcello Benincasa, Enrico Maiorca, Davide Scarabattoli, Fabio Ferri, and Danilo di Blasio
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0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,02 engineering and technology - Abstract
This paper describes the process of design, analysis, and scoring with both subjective and objective criteria, of a set of possible haptic inceptors configurations to be used as primary flight control devices for a class of future tilt rotor vehicles. Several scoring criteria were adopted like ergonomics, cognitive compatibility, easiness of recovery in fault situations, and expected workload among several others. Each criterion was weighted to obtain a scoring matrix for a total of 18 different configurations, some "classic", some novel, leading to an overall ranking. The matrix was used to select the best candidate configurations to be tested using a human-in-the-loop simulator in the context of the EU Funded CleanSky2 SMARTeR Project. After a final review phase, the best solution will be adopted to actually fly the Leonardo NextGen Civil Tilt Rotor Technological Demonstrator in the context of the EU Funded CleanSky2 SAIS Project.
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- 2022
3. The Gaia-ESO Survey: Kinematic structure in the Gamma Velorum cluster$^{⋆,⋆⋆}$
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R. J. Jackson, G. G. Sacco, Francesco Damiani, P. de Laverny, M. T. Costado, Thomas Bensby, Giuseppina Micela, Paula Jofre, Michiel Cottaar, James R. Lewis, Antonio Frasca, Sofia Randich, Karin Lind, Michael R. Meyer, L. Morbidelli, Sergey E. Koposov, Alejandra Recio-Blanco, Emilio J. Alfaro, Gerard Gilmore, R. D. Jeffries, Enrico Maiorca, Elena Pancino, A. Klutsch, A. C. Lanzafame, Sofia Feltzing, L. Prisinzano, E. Brugaletta, E. Franciosini, Laura Magrini, M. Caramazza, Koposov, Sergey [0000-0003-2644-135X], Gilmore, Gerard [0000-0003-4632-0213], and Apollo - University of Cambridge Repository
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astro-ph.SR ,010504 meteorology & atmospheric sciences ,stars: kinematics and dynamics ,Population ,Binary number ,FOS: Physical sciences ,Astrophysics ,Kinematics ,stars: pre-main sequence ,Vela ,01 natural sciences ,Virial theorem ,0103 physical sciences ,Cluster (physics) ,education ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,education.field_of_study ,stars: formation ,Astronomy and Astrophysics ,Radial velocity ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,open clusters and associations: individual: gamma2 Velorum - Abstract
Context. A key science goal of the Gaia-ESO survey (GES) at the VLT is to use the kinematics of low-mass stars in young clusters and star forming regions to probe their dynamical histories and how they populate the field as they become unbound. The clustering of low-mass stars around the massive Wolf-Rayet binary system γ$^{2}$ Velorum was one of the first GES targets. Aims. We empirically determine the radial velocity precision of GES data, construct a kinematically unbiased sample of cluster members and characterise their dynamical state. Methods. Targets were selected from colour–magnitude diagrams and intermediate resolution spectroscopy was used to derive radial velocities and assess membership from the strength of the Li i 6708 Å line. The radial velocity distribution was analysed using a maximum likelihood technique that accounts for unresolved binaries. Results. The GES radial velocity precision is about 0.25 km s$^{-1}$ and sufficient to resolve velocity structure in the low-mass population around γ$^{2}$ Vel. The structure is well fitted by two kinematic components with roughly equal numbers of stars; the first has an intrinsic dispersion of 0.34 ± 0.16 km s $^{-1}$, consistent with virial equilibrium. The second has a broader dispersion of 1.60 ± 0.37 km s$^{-1}$ and is offset from the first by 2 km s$^{-1}$. The first population is older by 1–2 Myr based on a greater level of Li depletion seen among its M-type stars and is probably more centrally concentrated around γ$^{2}$ Vel. Conclusions. We consider several formation scenarios, concluding that the two kinematic components are a bound remnant of the original, denser cluster that formed γ$^{2}$ Vel, and a dispersed population from the wider Vela OB2 association, of which γ$^{2}$ Vel is the most massive member. The apparent youth of γ$^{2}$ Vel compared to the older (≥10 Myr) low-mass population surrounding it suggests a scenario in which the massive binary formed in a clustered environment after the formation of the bulk of the low-mass stars., This work was partially supported by the Gaia Research for European Astronomy Training (GREAT-ITN) Marie Curie network, funded through the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement 264895 and supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell’ Istruzione, dell’ Università e della Ricerca (MIUR) in the form of the grant “Premiale VLT 2012”. RJJ acknowledges financial support from the UK Science and Technology Facilities Council.
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- 2017
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4. The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
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Thomas Nordlander, R. Sordo, C. Babusiaux, D. Montes, P. Gruyters, Ettore Flaccomio, Laura Magrini, C. Muñoz, Sergey E. Koposov, C. Allende Prieto, Eileen D. Friel, Giovanni Carraro, K. Biazzo, S. Duffau, Thomas Masseron, G. G. Sacco, Martin Asplund, Carmela Lardo, Luca Sbordone, M. T. Costado, Ignacio Negueruela, Annette M. N. Ferguson, S. Blanco-Cuaresma, Amelia Bayo, Ch. Martayan, I. San Roman, Lorenzo Monaco, Nuno C. Santos, L. Morbidelli, Ulrike Heiter, Enrico Maiorca, Sofia Feltzing, H. W. Rix, Janet E. Drew, Caroline Soubiran, Guillaume Guiglion, Gregory R. Ruchti, Antonella Vallenari, S. Van Eck, Vanessa Hill, P. Donati, S. G. Sousa, Rodolfo Smiljanic, Heather R. Jacobson, Marc Weber, James Binney, Giuseppina Micela, Bengt Edvardsson, R. D. Jeffries, Marica Valentini, Angela Bragaglia, Thierry Morel, Y. Chorniy, Michael G. Irwin, G. Barisevičius, A. C. Lanzafame, L. Prisinzano, Jack Lewis, E. Delgado-Mena, Lorenzo Spina, Hans-Günter Ludwig, Simone Zaggia, P. Francois, S. Villanova, Nils Ryde, N. A. Walton, E. Puzeras, R. J. Jackson, Elena Pancino, J. I. González Hernández, Piercarlo Bonifacio, Šarūnas Mikolaitis, Gerard Gilmore, Thomas Bensby, Alessio Mucciarelli, Douglas Geisler, Paula Jofre, T. Prusti, Sofia Randich, Matthias Steffen, Karin Lind, P. de Laverny, Gianni Marconi, Clare Worley, R. Blomme, Camilla Juul Hansen, Emilio J. Alfaro, E. Franciosini, Tristan Cantat-Gaudin, Alejandra Recio-Blanco, Henrik Jönsson, V. Zh. Adibekyan, Grazina Tautvaisiene, Hugo M. Tabernero, Andreas Korn, Elisabetta Caffau, Francesco Damiani, A. Hourihane, Aldo Serenelli, Maria Bergemann, Antonio Frasca, L. Pasquini, Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Astrofísica Estelar (AE), Smiljanic, R., Korn, A. J., Bergemann, M., Frasca, A., Magrini, L., Masseron, T., Pancino, E., Ruchti, G., San Roman, I., Sbordone, L., Sousa, S. G., Tabernero, H., Tautvaišienė, G., Valentini, M., Weber, M., Worley, C. C., Adibekyan, V. Zh., Allende Prieto, C., Barisevičius, G., Biazzo, K., Blanco-Cuaresma, S., Bonifacio, P., Bragaglia, A., Caffau, E., Cantat-Gaudin, T., Chorniy, Y., de Laverny, P., Delgado-Mena, E., Donati, P., Duffau, S., Franciosini, E., Friel, E., Geisler, D., González Hernández, J. I., Gruyters, P., Guiglion, G., Hansen, C. J., Heiter, U., Hill, V., Jacobson, H. R., Jofre, P., Jönsson, H., Lanzafame, A. C., Lardo, C., Ludwig, H.-G., Maiorca, E., Mikolaitis, Š., Montes, D., Morel, T., Mucciarelli, A., Muñoz, C., Nordlander, T., Pasquini, L., Puzeras, E., Recio-Blanco, A., Ryde, N., Sacco, G., Santos, N. C., Serenelli, A. M., Sordo, R., Soubiran, C., Spina, L., Steffen, M., Vallenari, A., Van Eck, S., Villanova, S., Gilmore, G., Randich, S., Asplund, M., Binney, J., Drew, J., Feltzing, S., Ferguson, A., Jeffries, R., Micela, G., Negueruela, I., Prusti, T., Rix, H.-W., Alfaro, E., Babusiaux, C., Bensby, T., Blomme, R., Flaccomio, E., François, P., Irwin, M., Koposov, S., Walton, N., Bayo, A., Carraro, G., Costado, M. T., Damiani, F., Edvardsson, B., Hourihane, A., Jackson, R., Lewis, J., Lind, K., Marconi, G., Martayan, C., Monaco, L., Morbidelli, L., Prisinzano, L., Zaggia, S., Department of Astronomy and Space Physics [Uppsala], Uppsala University, M2A 2014, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Lund Observatory, Lund University [Lund], INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), Université de Liège, Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto, Departamento de Física e Astronomia [Porto] (DFA/FCUP), Faculdade de Ciências da Universidade do Porto (FCUP), Universidade do Porto-Universidade do Porto, Laboratoire des Agrégats Moléculaires et Matériaux Inorganiques (LAMMI), Centre National de la Recherche Scientifique (CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2), Institut d'Astronomie et d'Astrophysique, Université libre de Bruxelles (ULB), INAF - Osservatorio Astronomico di Palermo (OAPa), Agence Spatiale Européenne (ESA), European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), European Southern Observatory (ESO), Naval Postgraduate School (U.S.), and Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS)
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Astrofísica ,stars: abundances ,High resolution ,FOS: Physical sciences ,Scale (descriptive set theory) ,Astrophysics ,Type (model theory) ,Parameter space ,Surveys ,01 natural sciences ,fundamental parameters [Stars] ,Spectral line ,surveys ,0103 physical sciences ,Stars, fundamental parameters ,methods, data analysis ,data analysis [Methods] ,010303 astronomy & astrophysics ,methods: data analysis, surveys, stars: abundances, stars: fundamental parameters, stars: late-type ,Solar and Stellar Astrophysics (astro-ph.SR) ,QC ,Astronomía y Astrofísica ,QB ,Physics ,010308 nuclear & particles physics ,stars: late-type ,Astronomy and Astrophysics ,[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,methods: data analysis ,Stars, abundances ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Astronomía ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,Globular cluster ,abundances [Stars] ,late-type [Stars] ,Stars, late type ,stars: fundamental parameters ,Dispersion (chemistry) - Abstract
The Gaia-ESO Survey is obtaining high-quality spectroscopic data for about 10^5 stars using FLAMES at the VLT. UVES high-resolution spectra are being collected for about 5000 FGK-type stars. These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO 2nd internal release and will be part of its 1st public release of advanced data products. The final parameter scale is tied to the one defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. A set of open and globular clusters is used to evaluate the physical soundness of the results. Each methodology is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted-medians of those from the individual methods. The recommended results successfully reproduce the benchmark stars atmospheric parameters and the expected Teff-log g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55 K for Teff, 0.13 dex for log g, and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for Teff, 0.10-0.25 dex for log g, and 0.05-0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex., Comment: 39 pages, A&A accepted
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- 2016
5. The Solar Photospheric Nitrogen Abundance
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R. Faraggiana, Maurizio Busso, Inga Kamp, Elisabetta Caffau, H.-G. Ludwig, Piercarlo Bonifacio, Matthias Steffen, Enrico Maiorca, and Astronomy
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Thermodynamic equilibrium ,chemistry.chemical_element ,FOS: Physical sciences ,Solar photosphere ,LINES ,Astrophysics ,Spectral line ,Sun: granulation Hydrodynamics ,OXYGEN ,Sun: granulation ,Abundance (ecology) ,Astrophysics::Solar and Stellar Astrophysics ,STATISTICAL EQUILIBRIUM ,Sun: abundances ,Sun:atmosphere ,Solar and Stellar Astrophysics (astro-ph.SR) ,Physics ,SUN ,Astronomy and Astrophysics ,HYDROGEN ,Nitrogen ,Line formation ,chemistry ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,radiative transfer ,Radiation hydrodynamics ,hydrodynamics ,Astrophysics::Earth and Planetary Astrophysics ,line: formation ,Equivalent width ,Nucleosynthesis ,Intensity (heat transfer) ,Sun: atmosphere - Abstract
We present a new determination of the solar nitrogen abundance making use of 3D hydrodynamical modelling of the solar photosphere, which is more physically motivated than traditional static 1D models. We selected suitable atomic spectral lines, relying on equivalent width measurements already existing in the literature. For atmospheric modelling we used the co 5 bold 3D radiation hydrodynamics code. We investigated the influence of both deviations from local thermodynamic equilibrium (non-LTE effects) and photospheric inhomogeneities (granulation effects) on the resulting abundance. We also compared several atlases of solar flux and centre-disc intensity presently available. As a result of our analysis, the photospheric solar nitrogen abundance is A(N) = 7.86 +/- 0.12., Comment: 6 pages, 4 figures
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- 2009
6. The Gaia-ESO Survey: Chromospheric emission, accretion properties, and rotation in gamma Velorum and Chamaeleon
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A. Hourihane, Geert Barentsen, E. Brugaletta, Beate Stelzer, Gerry Gilmore, Paula Jofre, E. Franciosini, Thomas Masseron, G. Pace, K. Biazzo, L. Morbidelli, Luca Pasquini, Emilio J. Alfaro, A. C. Lanzafame, Lorenzo Spina, R. Bonito, Carmela Lardo, Sofia Randich, A. Bragaglia, M. T. Costado, A. Klutsch, C. C. Worley, Enrico Maiorca, S. G. Sousa, Antonio Frasca, J. F. Gameiro, G. G. Sacco, Loredana Prisinzano, Giuseppina Micela, J. M. Alcalá, V. Hill, D. Montes, Javier Lopez-Santiago, Amelia Bayo, R. D. Jeffries, Ettore Flaccomio, ITA, Frasca A., Biazzo K., Lanzafame A.C., Alcala J.M., Brugaletta E., Klutsch A., Stelzer B., Sacco G.G., Spina L., Jeffries R.D., Montes D., Alfaro E.J., Barentsen G., Bonito R., Gameiro J.F., Lopez-Santiago J., Pace G., Pasquini L., Prisinzano L., Sousa S.G., Gilmore G., Randich S., Micela G., Bragaglia A., Flaccomio E., Bayo A., Costado M.T., Franciosini E., Hill V., Hourihane A., Jofre P., Lardo C., Maiorca E., Masseron T., Morbidelli L., Worley C.C., Frasca, A., Biazzo, K., Lanzafame, A., Alcalá, J., Brugaletta, E., Klutsch, A., Stelzer, B., Sacco, G., Spina, L., Jeffries, R., Montes, D., Alfaro, E., Barentsen, G., Bonito, R., Gameiro, J., López-Santiago, J., Pace, G., Pasquini, L., Prisinzano, L., Sousa, S., Gilmore, G., Randich, S., Micela, G., Bragaglia, A., Flaccomio, E., Bayo, A., Costado, M., Franciosini, E., Hill, V., Hourihane, A., Jofré, P., Lardo, C., Maiorca, E., Masseron, T., Morbidelli, L., and Worley, C.
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Astrofísica ,stars: chromospheres ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Rotation ,Stars: chromosphere ,Open clusters and associations: individual:γVelorum ,stars: low-mass ,Stars: low-ma ,Astrophysics::Solar and Stellar Astrophysics ,Open clusters and associations: individual: Chamaeleon I ,open clusters and associations: individual: γ Velorum ,QC ,Astrophysics::Galaxy Astrophysics ,QB ,Line (formation) ,Physics ,Accretion (meteorology) ,Diagram ,Stars: rotation ,Spectral density ,Astronomy and Astrophysics ,Astronomy and Astrophysic ,Stars ,Distribution (mathematics) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Chamaeleon ,Stars: pre-main sequence ,Astrophysics::Earth and Planetary Astrophysics ,Stars: chromospheres ,Stars: low-mass - Abstract
Aims: One of the goals of the Gaia-ESO Survey (GES), which is conducted with FLAMES at the VLT, is the census and the characterization of the low-mass members of very young clusters and associations. We conduct a comparative study of the main properties of the sources belonging to γ Velorum (γ Vel) and Chamaeleon I (Cha I) young associations, focusing on their rotation, chromospheric radiative losses, and accretion. Methods: We used the fundamental parameters (effective temperature, surface gravity, lithium abundance, and radial velocity) delivered by the GES consortium in the first internal data release to select the members of γ Vel and Cha I among the UVES and GIRAFFE spectroscopic observations. A total of 140 γ Vel members and 74 Cha I members were studied. The procedure adopted by the GES to derive stellar fundamental parameters also provided measures of the projected rotational velocity (vsini). We calculated stellar luminosities through spectral energy distributions, while stellar masses were derived by comparison with evolutionary tracks. The spectral subtraction of low-activity and slowly rotating templates, which are rotationally broadened to match the vsini of the targets, enabled us to measure the equivalent widths (EWs) and the fluxes in the Hα and Hβ lines. The Hα line was also used for identifying accreting objects, on the basis of its EW and the width at the 10% of the line peak (10%W), and for evaluating the mass accretion rate (Ṁacc). Results: The distribution of vsini for the members of γ Vel displays a peak at about 10 km s-1 with a tail toward faster rotators. There is also some indication of a different vsini distribution for the members of its two kinematical populations. Most of these stars have Hα fluxes corresponding to a saturated activity regime. We find a similar distribution, but with a narrower peak, for Cha I. Only a handful of stars in γ Vel display signatures of accretion, while many more accretors were detected in the younger Cha I, where the highest Hα fluxes are mostly due to accretion, rather than to chromospheric activity. Accreting and active stars occupy two different regions in a Teff-flux diagram and we propose a criterion for distinguishing them. We derive Ṁacc in the ranges 10-11-10-9 M☉ yr-1 and 10-10-10-7 M☉ yr-1 for γ Vel and Cha I accretors, respectively. We find less scatter in the Ṁacc - M⋆ relation derived through the Hα EWs, when compared to the Hα10%W diagnostics, in agreement with other authors. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002.Tables 5, 6, and Appendix A are available in electronic form at http://www.aanda.orgTables 2-4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A4
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- 2015
7. $s$-Processing in AGB Stars Revisited. II. Enhanced $^{13}$C Production Through MHD-Induced Mixing
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Enrico Maiorca, Maria Clara Nucci, Oscar Trippella, Sara Palmerini, and Maurizio Busso
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Proton ,abundances, stars: AGB and post-AGB, magnetohydrodynamics (MHD), methods: analytical, nuclear reactions, nucleosynthesis, stars: low-mass, stars: magnetic field, Space and Planetary Science, Astronomy and Astrophysics ,FOS: Physical sciences ,stars: AGB and post-AGB ,Astrophysics ,magnetohydrodynamics (MHD) ,01 natural sciences ,methods: analytical ,stars: low-mass ,Nucleosynthesis ,0103 physical sciences ,Asymptotic giant branch ,Astrophysics::Solar and Stellar Astrophysics ,Neutron ,010303 astronomy & astrophysics ,Conservation of mass ,nuclear reactions ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Oxygen-16 ,Physics ,abundances ,010308 nuclear & particles physics ,stars: magnetic field ,nucleosynthesis ,Astronomy and Astrophysics ,Giant star ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science - Abstract
Slow neutron captures are responsible for the production of about $50\%$ of elements heavier than iron, mainly, occurring during the asymptotic giant branch phase of low-mass stars ($1$ $\lesssim M$/M$_{\odot}$ $\lesssim$ $3$), where the main neutron source is the $^{13}$C($\alpha$,n)$^{16}$O reaction. This last is activated from locally-produced $^{13}$C, formed by partial mixing of hydrogen into the He-rich layers. We present here the first attempt at describing a physical mechanism for the formation of the $^{13}$C reservoir, studying the mass circulation induced by magnetic buoyancy and without adding new free parameters to those already involved in stellar modelling. Our approach represents the application, to the stellar layers relevant for $s$-processing, of recent exact, analytical 2D and 3D models for magneto-hydrodynamic processes at the base of convective envelopes in evolved stars in order to promote downflows of envelope material for mass conservation, during the occurrence of a dredge-up phenomenon. We find that the proton penetration is characterized by small concentrations, but extended over a large fractional mass of the He-layers, thus producing $^{13}$C reservoirs of several $10^{-3}$ M$_{\odot}$. The ensuing $^{13}$C-enriched zone has an almost flat profile, while only a limited production of $^{14}$N occurs. In order to verify the effects of our new findings we show how the abundances of the main $s$-component nuclei can be accounted for in solar proportions and how our large $^{13}$C-reservoir allows us to solve a few so far unexplained features in the abundance distribution of post-AGB objects.
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- 2015
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8. The Gaia-ESO Survey: the Galactic thick to thin disc transition
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Angela Bragaglia, Ulrike Heiter, Georges Kordopatis, R. D. Jeffries, L. Morbidelli, Emilio J. Alfaro, A. Hourihane, R. J. Jackson, Vardan Adibekyan, P. Joffre, Laura Magrini, Maria Bergemann, A. C. Lanzafame, Jack Lewis, L. Prinsinzano, R. F. G. Wyse, C. Allende Prieto, V. Hill, Enrico Maiorca, Martin Asplund, Amina Helmi, Rodolfo Smiljanic, P. de Laverny, G. G. Sacco, Clare Worley, Elena Pancino, Antonella Vallenari, M. T. Costado, Gerard Gilmore, Giuseppina Micela, Sergey E. Koposov, Andreas Korn, Alejandra Recio-Blanco, Thomas Bensby, Carmela Lardo, Ettore Flaccomio, Sofia Feltzing, Sofia Randich, Karin Lind, Recio-Blanco A., De Laverny P., Kordopatis G., Helmi A., Hill V., Gilmore G., Wyse R., Adibekyan V., Randich S., Asplund M., Feltzing S., Jeffries R., Micela G., Vallenari A., Alfaro E., Allende Prieto C., Bensby T., Bragaglia A., Flaccomio E., Koposov S.E., Korn A., Lanzafame A., Pancino E., Smiljanic R., Jackson R., Lewis J., Magrini L., Morbidelli L., Prisinzano L., Sacco G., Worley C.C., Hourihane A., Bergemann M., Costado M.T., Heiter U., Joffre P., Lardo C., Lind K., Maiorca E., and Astronomy
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stars: abundances ,astro-ph.GA ,Metallicity ,Population ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Spectral line ,Galaxy: disk ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,education ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Physics ,Orbital elements ,education.field_of_study ,Galaxy: stellar content ,Number density ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Radius ,Galactic plane ,Astrophysics - Astrophysics of Galaxies ,Galaxy: abundance ,Stars ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Galaxy: abundances ,Astrophysics::Earth and Planetary Astrophysics - Abstract
(Abridged) We have used the atmospheric parameters, [alpha/Fe] abundances and radial velocities, determined from the Gaia-ESO Survey GIRAFFE spectra of FGK-type stars (iDR1), to provide a chemo-kinematical characterisation of the disc stellar populations. We focuss on a subsample of 1016 stars with high quality parameters, covering the volume |Z, Accepted for publication in Astronomy and Astrophysics
- Published
- 2014
9. The Gaia-ESO Survey::Properties of the intermediate age open cluster NGC 4815
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Thomas Bensby, Paula Jofre, Heather R. Jacobson, Tristan Cantat-Gaudin, Vanessa Hill, Alejandra Recio-Blanco, M. T. Costado, Angela Bragaglia, Emilio J. Alfaro, E. Franciosini, R. D. Jeffries, Grazina Tautvaisiene, Laura Magrini, Andreas Korn, Elena Pancino, Giovanni Carraro, Eileen D. Friel, Gerard Gilmore, Monica Tosi, R. J. Jackson, Loredana Prisinzano, G. G. Sacco, A. Hourihane, L. Morbidelli, Enrico Maiorca, P. de Laverny, Clare Worley, Rodolfo Smiljanic, Sergey E. Koposov, Sofia Randich, Karin Lind, P. Sestito, P. Donati, Antonella Vallenari, Simone Zaggia, F. M. Jimenez-Estebae, and R. Sordo
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Physics ,astro-ph.SR ,Metallicity ,astro-ph.GA ,FOS: Physical sciences ,Astronomy and Astrophysics ,Context (language use) ,Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Radial velocity ,Distance modulus ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Cluster (physics) ,Disc ,Solar and Stellar Astrophysics (astro-ph.SR) ,Open cluster - Abstract
NGC 4815 is a populous ~500 Myr open cluster at a Galactocentric radius of 7 kpc observed in the first six months of the Gaia-ESO Survey. Located in the inner Galactic disk, NGC 4815 is an important tracer of the abundance gradient, where few intermediate age open clusters are found. We use the survey derived radial velocities, stellar atmospheric parameters, metallicity, and elemental abundances for stars targeted as potential members of this cluster to carry out an analysis of cluster properties. The radial velocity distribution of stars in the cluster field is used to define the cluster systemic velocity and derive likely cluster membership for stars observed by the Gaia-ESO Survey. We investigate the distributions of Fe and Fe-peak elements, alpha-elements, and the light elements Na and Al and characterize the cluster's internal chemical homogeneity comparing it to the properties of radial velocity non-member stars. Utilizing these cluster properties, the cluster color-magnitude diagram is analyzed and theoretical isochrones are fit to derive cluster reddening, distance, and age. NGC 4815 is found to have a mean [Fe/H]=+0.03. Elemental abundances of cluster members show typically small internal variation, with internal dispersions of ~0.05 dex. [Ca/Fe] and [Si/Fe] show solar ratios, but [Mg/Fe] is moderately enhanced, while [Ti/Fe] appears slightly deficient. As with many open clusters, [Na/Fe] and [Al/Fe] are enhanced, [Na/Fe] significantly so, although the role of internal mixing and the assumption of LTE in the analysis remain to be investigated. From isochrone fits to color-magnitude diagrams, we find a cluster age of 0.5 to 0.63 Gyr, a reddening of E(B-V) = 0.59 to 0.65, and a true distance modulus (m-M) = 11.95 to 12.20, depending on the choice of theoretical models, leading to a Galactocentric distance of 6.9 kpc., 10 pages, 8 figures, published in Astronomy & Astrophysics
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- 2014
10. The Gaia-ESO Survey: Abundance ratios in the inner-disk open clusters Trumpler 20, NGC 4815, NGC 6705
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Gerard Gilmore, F. M. Jiménez-Esteban, Ulrike Heiter, Vanessa Hill, Jack Lewis, Lorenzo Spina, P. Donati, A. Hourihane, E. Friel, Grazina Tautvaisiene, E. Franciosini, Sergey E. Koposov, Enrico Maiorca, Carmela Lardo, Andreas Korn, Rodolfo Smiljanic, Sofia Feltzing, Antonella Vallenari, Monica Tosi, R. J. Jackson, Martin Asplund, Angela Bragaglia, Thomas Masseron, Heather R. Jacobson, P. Francois, C. Muñoz, P. de Laverny, Clare Worley, Nami Mowlavi, R. D. Jeffries, Maria Bergemann, I. San Roman, S. Villanova, S. Blanco-Cuaresma, Francesco Damiani, Tristan Cantat-Gaudin, Alejandra Recio-Blanco, Sofia Randich, Karin Lind, Donatella Romano, Ettore Flaccomio, Caroline Soubiran, Laura Magrini, Douglas Geisler, Paula Jofre, Simone Zaggia, Loredana Prisinzano, R. Sordo, G. G. Sacco, L. Morbidelli, Thomas Bensby, Elena Pancino, M. T. Costado, Laboratoire des Agrégats Moléculaires et Matériaux Inorganiques (LAMMI), Centre National de la Recherche Scientifique (CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2), M2A 2014, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Department of Astronomy and Space Physics [Uppsala], Uppsala University, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Magrini L., Randich S., Romano D., Friel E., Bragaglia A., Smiljanic R., Jacobson H., Vallenari A., Tosi M., Spina L., Donati P., Maiorca E., Cantat-Gaudin T., Sordo R., Bergemann M., Damiani F., Tautvaisiene G., Blanco-Cuaresma S., Jimenez-Esteban F., Geisler D., Mowlavi N., Munoz C., San Roman I., Soubiran C., Villanova S., Zaggia S., Gilmore G., Asplund M., Feltzing S., Jeffries R., Bensby T., Koposov S., Korn A.J., Flaccomio E., Pancino E., Recio-Blanco A., Sacco G., Costado M.T., Franciosini E., Jofre P., De Laverny P., Hill V., Heiter U., Hourihane A., Jackson R., Lardo C., Morbidelli L., Lewis J., Lind K., Masseron T., Prisinzano L., and Worley C.
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[PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Globular clusters: individual: NGC 6705 ,Metallicity ,astro-ph.GA ,FOS: Physical sciences ,Astrophysics ,Galaxy: disk ,Open clusters and associations: individual: NGC 4815 ,Bulge ,Abundance (ecology) ,Disc ,Galaxy: abundances ,Open clusters and associations: general ,Open clusters and associations: individual: Trumpler 20 ,Physics ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Galaxy: abundance ,Stars ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Content (measure theory) ,Open cluster - Abstract
Open clusters are key tools to study the spatial distribution of abundances in the disk and their evolution with time. Using the first release of stellar parameters and abundances of the Gaia-ESO Survey, we analyse the chemical properties of stars in three old/intermediate-age open clusters, namely NGC 6705, NGC 4815, and Trumpler 20, all located in the inner part of the Galactic disk at Galactocentric radius R$_{GC}\sim$7 kpc, aiming at proving their homogeneity and at comparing them with the field population. We study the abundance ratios of elements belonging to two different nucleosynthetic channels: $\alpha$-elements and iron-peak elements. The main results can be summarised as follows: i) cluster members are chemically homogeneous within 3-$\sigma$ in all analysed elements; ii) the three clusters have comparable [El/Fe] patters within $\sim$1-$\sigma$, but they differ in their global metal content [El/H], with NGC 4815 having the lowest metallicity. Their [El/Fe] ratios show differences and analogies with those of the field population, both in the solar neighbourhood and in the bulge/inner disk; iii) comparing the abundance ratios with the results of two chemical evolution models and with field star abundance distributions, we find that the abundance ratios of Mg, Ni, Ca in NGC 6705 might require an inner birthplace, implying a subsequent variation of its R$_{GC}$ during its lifetime, consistent with previous orbit determination. The full dataset of the Gaia-ESO Survey will be a superlative tool to constrain the chemical evolution of our Galaxy by disentangling different formation and evolution scenarios., Comment: 17 pages, 11 figures, A&A accepted
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- 2014
11. The Gaia -ESO Survey: Metallicity and kinematic trends in the Milky Way bulge
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Mathias Schultheis, Emilio J. Alfaro, C. Babusiaux, Dante Minniti, R. F. G. Wyse, A. C. Lanzafame, L. Morbidelli, Manuela Zoccali, Francesco Damiani, Enrico Maiorca, Rodolfo Smiljanic, Sofia Randich, Gerard Gilmore, Alejandra Recio-Blanco, P. de Laverny, Maria Bergemann, Clare Worley, Laura Magrini, Carmela Lardo, Ettore Flaccomio, Luca Sbordone, Sofia Feltzing, A. Hourihane, Oscar A. Gonzalez, Angela Bragaglia, Simone Zaggia, Vanessa Hill, Paula Jofre, Antonella Vallenari, A. Rojas-Arriagada, Thomas Bensby, M. T. Costado, Elena Pancino, Rojas-Arriagada A., Recio-Blanco A., Hill V., De Laverny P., Schultheis M., Babusiaux C., Zoccali M., Minniti D., Gonzalez O.A., Feltzing S., Gilmore G., Randich S., Vallenari A., Alfaro E.J., Bensby T., Bragaglia A., Flaccomio E., Lanzafame A.C., Pancino E., Smiljanic R., Bergemann M., Costado M.T., Damiani F., Hourihane A., Jofre P., Lardo C., Magrini L., Maiorca E., Morbidelli L., Sbordone L., Worley C.C., Zaggia S., Wyse R., Pontificia Universidad Católica de Chile (UC), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universidad Andrés Bello [Santiago] (UNAB), Lund Observatory, Lund University [Lund], Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astronomico di Bologna (OABO), INAF - Osservatorio Astrofisico di Catania (OACT), Polish Academy of Sciences (PAN), University of Turin, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), INAF - Osservatorio Astrofisico di Arcetri (OAA), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
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Vista Variables in the Via Lactea ,Milky Way ,Metallicity ,Population ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Galaxy: bulge ,Bulge ,education ,ComputingMilieux_MISCELLANEOUS ,Astrophysics::Galaxy Astrophysics ,[PHYS]Physics [physics] ,Physics ,education.field_of_study ,Galaxy: stellar content ,Stars: abundances ,Velocity dispersion ,Astronomy and Astrophysics ,Galactic plane ,Astrophysics - Astrophysics of Galaxies ,Galaxy: abundance ,Stars ,Space and Planetary Science ,Galaxy: formation ,Astrophysics of Galaxies (astro-ph.GA) ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
(Abridged) We analyzed the stellar parameters and radial velocities of ~1200 stars in five bulge fields as determined from the Gaia-ESO survey data (iDR1). We use VISTA Variables in The Via Lactea (VVV) photometry to obtain reddening values by using a semi-empirical T_eff-color calibration. From a Gaussian decomposition of the metallicity distribution functions, we unveil a clear bimodality in all fields, with the relative size of components depending of the specific position on the sky. In agreement with some previous studies, we find a mild gradient along the minor axis (-0.05 dex/deg between b=-6 and b=-10) that arises from the varying proportion of metal-rich and metal-poor components. The number of metal-rich stars fades in favor of the metal-poor stars with increasing b. The K-magnitude distribution of the metal-rich population splits into two peaks for two of the analyzed fields that intersects the near and far branches of the X-shaped bulge structure. In addition, two lateral fields at (l,b)=(7,-9) and (l,b)=(-10,-8) present contrasting characteristics. In the former, the metallicity distribution is dominated by metal-rich stars, while in the latter it presents a mix of a metal-poor population and and a metal-intermediate one, of nearly equal sizes. Finally, we find systematic differences in the velocity dispersion between the metal-rich and the metal-poor components of each field. Our chemo-kinematical analysis is consistent with a varying field-to-field proportion of stars belonging to (i) a metal-rich boxy/peanut X-shaped component, with bar-like kinematics, and (ii) a metal-poor more extended rotating structure with a higher velocity dispersion that dominates far from the Galactic plane. These first GES data allow studying the detailed spatial dependence of the Galactic bulge populations, thanks to the analysis of individual fields with relatively high statistics., Accepted for publication in Astronomy and Astrophysics
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- 2014
12. Gaia-ESO Survey: Empirical classification of VLT/Giraffe stellar spectra in the wavelength range 6440-6810 angstrom in the gamma Velorum cluster, and calibration of spectral indices
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Thomas Bensby, Francesco Damiani, A. Hourihane, C. C. Worley, Ettore Flaccomio, Alejandra Recio-Blanco, A. Bragaglia, Gerry Gilmore, Elena Pancino, Paula Jofre, R. J. Jackson, M. T. Costado, A. C. Lanzafame, R. D. Jeffries, G. G. Sacco, Emilio J. Alfaro, P. de Laverny, Enrico Maiorca, Rodolfo Smiljanic, L. Morbidelli, Yves Fremat, Loredana Prisinzano, Sofia Randich, Karin Lind, Giuseppina Micela, and Janet E. Drew
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media_common.quotation_subject ,Population ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,stars: pre-main sequence ,01 natural sciences ,Astronomical spectroscopy ,Spectral line ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,education ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,media_common ,Physics ,education.field_of_study ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Giant star ,stars: fundamental parameters ,open clusters and associations: individual: gamma2 Velorum ,Accretion (astrophysics) ,Stars ,Photometry (astronomy) ,Space and Planetary Science ,Sky ,Astrophysics::Earth and Planetary Astrophysics - Abstract
We study spectral diagnostics available from optical spectra with R=17000 obtained with the VLT/Giraffe HR15n setup, using observations from the Gaia-ESO Survey, on the gamma Vel young cluster, in order to determine the fundamental parameters of these stars. We define a set of spectroscopic indices, sampling TiO bands, H-alpha core and wings, and many temperature- and gravity-sensitive lines. Combined indices tau (gamma) are also defined as Teff (log g) indicators over a wide spectral-type range. H-alpha emission-line indices are also chromospheric activity or accretion indicators. A metallicity-sensitive index is also defined. These indices enable us to find a clear difference between gravities of main-sequence and pre-main-sequence stars (as well as giant stars): the (gamma,tau) diagram is thus argued to be a promising distance-independent age measurement tool for young clusters. Our indices were quantitatively calibrated by means of photometry and literature reference spectra (from UVES-POP and ELODIE 3.1 Libraries, and other datasets), over a wide range of stellar parameters. The ability of our indices to select peculiar, or other rare classes of stars is also established. Finally, our gravity determinations support the existence of an older pre-main-sequence population in the gamma Vel sky region, in agreement with the lithium depletion pattern of those stars (abridged).
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- 2014
13. The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge
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Alejandra Recio-Blanco, David M. Nataf, Sofia Randich, Karin Lind, A. Hourihane, Carmela Lardo, Sofia Feltzing, G. G. Sacco, Martin Asplund, C. C. Worley, Paula Jofre, Andreas Korn, David Yong, C. Allende Prieto, L. M. Howes, G. S. Da Costa, Enrico Maiorca, Manuela Zoccali, Francesco Damiani, L. Morbidelli, Vanessa Hill, Maria Bergemann, Ulrike Heiter, Andrew R. Casey, Rodolfo Smiljanic, Gerard Gilmore, Stefan Keller, Michael S. Bessell, Dante Minniti, Patrick Tisserand, Laura Magrini, Anna F. Marino, Brian P. Schmidt, Antonella Vallenari, Thomas Masseron, Luca Casagrande, Ettore Flaccomio, P. de Laverny, Elena Pancino, Thomas Bensby, Christopher Owen, M. T. Costado, Howes L.M., Asplund M., Casey A.R., Keller S.C., Yong D., Gilmore G., Lind K., Worley C., Bessell M.S., Casagrande L., Marino A.F., Nataf D.M., Owen C.I., Da Costa G.S., Schmidt B.P., Tisserand P., Randich S., Feltzing S., Vallenari A., Allende Prieto C., Bensby T., Flaccomio E., Korn A.J., Pancino E., Recio-Blanco A., Smiljanic R., Bergemann M., Costado M.T., Damiani F., Heiter U., Hill V., Hourihane A., Jofre P., Lardo C., de Laverny P., Magrini L., Maiorca E., Masseron T., Morbidelli L., Sacco G.G., Minniti D., and Zoccali M.
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010504 meteorology & atmospheric sciences ,Evolution ,Metallicity ,K-type main-sequence star ,Milky Way ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Bulge ,0103 physical sciences ,Galaxy formation and evolution ,Population II-Galaxy ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,Spiral galaxy ,Bulge-Galaxy ,Astronomy ,Astronomy and Astrophysics ,Stars ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Abundances-star ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Earth and Planetary Astrophysics - Abstract
We present the first results of the EMBLA survey (Extremely Metal-poor BuLge stars with AAOmega), aimed at finding metal-poor stars in the Milky Way bulge, where the oldest stars should now preferentially reside. EMBLA utilises SkyMapper photometry to pre-select metal-poor candidates, which are subsequently confirmed using AAOmega spectroscopy. We describe the discovery and analysis of four bulge giants with -2.72, Comment: 7 pages, 5 figures. Accepted for publication by MNRAS
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- 2014
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14. The Gaia-ESO Survey: Stellar content and elemental abundances in the massive cluster NGC 6705
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Douglas Geisler, Paula Jofre, Thomas Bensby, A. Hourihane, A. Kupcu-Yoldas, Gerard Gilmore, F. M. Jiménez-Esteban, Robert Greimel, L. Prisinzano, E. Puzeras, E. A. Gonzalez-Solares, Ettore Flaccomio, Carmela Lardo, Arnas Drazdauskas, P. Donati, Tristan Cantat-Gaudin, Alejandra Recio-Blanco, A. Klutsch, A. C. Lanzafame, I. San, L. Sampedro, Luca Sbordone, Emilio J. Alfaro, Enrico Maiorca, L. Balaguer-Núñez, S. Villanova, Elena Pancino, Simone Zaggia, Despina Hatzidimitriou, H. J. Farnhill, Laura Magrini, J. Eisloeffel, Rodolfo Smiljanic, Antonella Vallenari, Angela Bragaglia, A. Spagna, Ummi Abbas, Monica Tosi, R. Blomme, Heather R. Jacobson, Alberto Vecchiato, Clare Worley, G. G. Sacco, L. Morbidelli, Mike Irwin, Janet E. Drew, R. Sordo, Thomas Masseron, Carme Jordi, Sofia Randich, Grazina Tautvaisiene, Francesco Damiani, P. deLaverny, M. T. Costado, Eileen D. Friel, Cantat-Gaudin T., Vallenari A., Zaggia S., Bragaglia A., Sordo R., Drew J.E., Eisloeffel J., Farnhill H.J., Gonzalez-Solares E., Greimel R., Irwin M.J., Kupcu-Yoldas A., Jordi C., Blomme R., Sampedro L., Costado M.T., Alfaro E., Smiljanic R., Magrini L., Donati P., Friel E.D., Jacobson H., Abbas U., Hatzidimitriou D., Spagna A., Vecchiato A., Balaguer-Nunez L., Lardo C., Tosi M., Pancino E., Klutsch A., Tautvaisiene G., Drazdauskas A., Puzeras E., Jimenez-Esteban F., Maiorca E., Geisler D., San Roman I., Villanova S., Gilmore G., Randich S., Bensby T., Flaccomio E., Lanzafame A., Recio-Blanco A., Damiani F., Hourihane A., Jofre P., De Laverny P., Masseron T., Morbidelli L., Prisinzano L., Sacco G.G., Sbordone L., and Worley C.C.
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Physics ,010308 nuclear & particles physics ,Milky Way ,Metallicity ,Stars: abundances ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Open clusters and associations: general ,01 natural sciences ,Open clusters and associations: individual: NGC 6705 ,Photometry (optics) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Globular cluster ,0103 physical sciences ,Cluster (physics) ,Mass segregation ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Red clump ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Open cluster - Abstract
Context. Chemically inhomogeneous populations are observed in most globular clusters, but not in open clusters. Cluster mass seems to play a key role in the existence of multiple populations. Aims. Studying the chemical homogeneity of the most massive open clusters is needed to better understand the mechanism of their formation and determine the mass limit under which clusters cannot host multiple populations. Here we studied NGC≠6705, which is a young and massive open cluster located towards the inner region of the Milky Way. This cluster is located inside the solar circle. This makes it an important tracer of the inner disk abundance gradient. Methods. This study makes use of BVI and ri photometry and comparisons with theoretical isochrones to derive the age of NGC≠6705. We study the density profile of the cluster and the mass function to infer the cluster mass. Based on abundances of the chemical elements distributed in the first internal data release of the Gaia-ESO Survey, we study elemental ratios and the chemical homogeneity of the red clump stars. Radial velocities enable us to study the rotation and internal kinematics of the cluster. Results. The estimated ages range from 250 to 316≠Myr, depending on the adopted stellar model. Luminosity profiles and mass functions show strong signs of mass segregation. We derive the mass of the cluster from its luminosity function and from the kinematics, finding values between 3700 M and 11 000 M. After selecting the cluster members from their radial velocities, we obtain a metallicity of [Fe/H] = 0.10 ± 0.06 based on 21 candidate members. Moreover, NGC 6705 shows no sign of the typical correlations or anti-correlations between Al, Mg, Si, and Na, which are expected in multiple populations. This is consistent with our cluster mass estimate, which is lower than the required mass limit proposed in the literature to develop multiple populations.
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- 2014
15. A new solar fluorine abundance and a fluorine determination in the two open clusters M 67 and NGC 6404
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Han Uitenbroek, Sofia Randich, Stefan Uttenthaler, Maurizio Busso, Laura Magrini, and Enrico Maiorca
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solar abundances ,spectroscop ,stars: evolution - stars: abundances - nucleosynthesis - stars: agb ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics ,01 natural sciences ,0103 physical sciences ,Cluster (physics) ,Astrophysics::Solar and Stellar Astrophysics ,Disc ,010303 astronomy & astrophysics ,Stellar evolution ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,Sunspot ,Very Large Telescope ,Astronomy and Astrophysics ,Solar telescope ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,HITRAN ,Astrophysics::Earth and Planetary Astrophysics ,Open cluster - Abstract
We present a new determination of the solar fluorine abundance together with abundance measurements of fluorine in two Galactic open clusters. We analyzed a sunspot spectrum, observed by L. Wallace and W. Livingston with the FTS at the McMath/Pierce Solar Telescope situated on Kitt Peak and spectra of four giants in the old cluster M 67 ($\sim$4.5 Gyr) and three giants in the young cluster NGC 6404 ($\sim$0.5 Gyr), obtained with the CRIRES spectrograph at VLT. Fluorine was measured through synthesis of the available HF lines. We adopted the recent set of experimental molecular parameters of HF delivered by the HITRAN database, and found a new solar fluorine abundance of $A(F) = 4.40\pm 0.25$, in good agreement with the M 67 average fluorine abundance of $A(F) = 4.49\pm 0.20$. The new solar abundance is in a very good agreement with the meteoritic value. The used modern spectrosynthesis tools, the agreement with the meteoritic value and with the results in open cluster M67, known to be a solar analogue, make our solar determination very robust. At the same time, the fluorine measurement in the above-mentioned open clusters is the first step in the understanding of its evolution during the last $\sim$10 Gyr in the Galactic disk. In order to develop this project, a larger sample of open clusters is required, so that it would allow us to trace the evolution of fluorine as a function of time and, in turn, to better understand its origin., Comment: accepted for publication in The Astrophysical Journal (updated version)
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- 2014
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16. The Gaia-ESO Survey: the chemical structure of the Galactic discs from the first internal data release
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Georges Kordopatis, Luca Sbordone, Francesco Damiani, Enrico Maiorca, Vanessa Hill, Simone Zaggia, Laura Magrini, P. de Laverny, S. G. Sousa, Rodolfo Smiljanic, Emilio J. Alfaro, Sofia Randich, C. Allende Prieto, Angela Bragaglia, S. Mikolaitis, Maria Bergemann, Giovanni Carraro, A. Hourihane, Alejandra Recio-Blanco, M. T. Costado, L. Morbidelli, Clare Worley, Giuseppina Micela, Grazina Tautvaisiene, Donatella Romano, A. C. Lanzafame, Paula Jofre, Antonella Vallenari, Ettore Flaccomio, Carmela Lardo, Sofia Feltzing, Gerard Gilmore, Thomas Bensby, Elena Pancino, Mikolaitis S., Hill V., Recio-Blanco A., De Laverny P., Allende Prieto C., Kordopatis G., Tautvaisiene G., Romano D., Gilmore G., Randich S., Feltzing S., Micela G., Vallenari A., Alfaro E.J., Bensby T., Bragaglia A., Flaccomio E., Lanzafame A.C., Pancino E., Smiljanic R., Bergemann M., Carraro G., Costado M.T., Damiani F., Hourihane A., Jofre P., Lardo C., Magrini L., Maiorca E., Morbidelli L., Sbordone L., Sousa S.G., Worley C.C., and Zaggia S.
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Physics ,Galaxy: stellar content ,Radial gradient ,Metallicity ,Techniques: spectroscopic ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Thin disc ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Galaxy: disk ,Bimodality ,Stars ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Dispersion (optics) ,Galaxy: disk / Galaxy: stellar content / techniques: spectroscopic ,Astrophysics::Earth and Planetary Astrophysics ,Data release ,Astrophysics::Galaxy Astrophysics - Abstract
Most high-resolution spectroscopic studies of the Galactic discs were mostly confined to objects in the solar vicinity. Here we aim at enlarging the volume in which individual chemical abundances are used to characterise both discs, using the first internal data release of the Gaia-ESO survey. We derive and discuss the abundances of eight elements (Mg, Al, Si, Ca, Ti, Fe, Cr, Ni, and Y). The trends of these elemental abundances with iron are very similar to those in the solar neighbourhood. We find a natural division between alpha-rich and alpha-poor stars, best seen in the bimodality of the [Mg/M] distributions in bins of metallicity, which we attribute to thick- and thin-disc sequences, respectively. With the possible exception of Al, the observed dispersion around the trends is well described by the expected errors, leaving little room for astrophysical dispersion. Using previously derived distances from Recio-Blanco et al. (2014b), we further find that the thick-disc is more extended vertically and is more centrally concentrated towards the inner Galaxy than the thin-disc, which indicates a shorter scale-length. We derive the radial and vertical gradients in metallicity, iron, four alpha-element abundances, and Al for the two populations, taking into account the identified correlation between R_GC and |Z|. Radial metallicity gradient is found in the thin disc. The positive radial individual [alpha/M] gradients found are at variance from the gradients observed in the RAVE survey. The thin disc also hosts a negative vertical metallicity gradient, accompanied by positive individual [alpha/M] and [Al/M] gradients. The thick-disc, presents no radial metallicity gradient, a shallower vertical metallicity gradient than the thin-disc, an alpha-elements-to-iron radial gradient in the opposite sense than that of the thin disc, and positive vertical individual [alpha/M] and [Al/M] gradients., Comment: 24 pages, 10 figures
- Published
- 2014
- Full Text
- View/download PDF
17. FAMA: An automatic code for stellar parameter and abundance determination
- Author
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Heather R. Jacobson, Enrico Maiorca, Roberto Baglioni, Tristan Cantat-Gaudin, Lorenzo Spina, Eileen D. Friel, Rosanna Sordo, Antonella Vallenari, Paolo Donati, Laura Magrini, Sofia Randich, and Angela Bragaglia
- Subjects
Dependency (UML) ,Computation ,FOS: Physical sciences ,Techniques: spectroscopic ,Context (language use) ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Surveys ,Spectral line ,Abundance (ecology) ,Methods: data analysis ,Astrophysics::Solar and Stellar Astrophysics ,Statistical physics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Physics ,Stars: abundances ,Astronomy and Astrophysics ,Open clusters and associations: general ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Globular cluster ,Moog ,Galaxy: abundances ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The large amount of spectra obtained during the epoch of extensive spectroscopic surveys of Galactic stars needs the development of automatic procedures to derive their atmospheric parameters and individual element abundances. Starting from the widely-used code MOOG by C. Sneden, we have developed a new procedure to determine atmospheric parameters and abundances in a fully automatic way. The code FAMA (Fast Automatic MOOG Analysis) is presented describing its approach to derive atmospheric stellar parameters and element abundances. The code, freely distributed, is written in Perl and can be used on different platforms. The aim of FAMA is to render the computation of the atmospheric parameters and abundances of a large number of stars using measurements of equivalent widths as automatic and as independent of any subjective approach as possible. It is based on the simultaneous search for three equilibria: excitation equilibrium, ionization balance, and the relationship between \fei\ and the reduced equivalent widths. FAMA also evaluates the statistical errors on individual element abundances and errors due to the uncertainties in the stellar parameters. The convergence criteria are not fixed 'a priori' but are based on the quality of the spectra. In this paper we present tests performed on the Solar spectrum EWs which tests the dependency on the initial parameters, and the analysis of a sample of stars observed in Galactic open and globular clusters., A&A accepted, 12 pages, 6 figures, 3 tables
- Published
- 2013
18. News on the s process from young open clusters
- Author
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Maurizio Busso, Oscar Trippella, Sara Palmerini, Sofia Randich, Enrico Maiorca, and Laura Magrini
- Subjects
Metallicity ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Stellar evolution ,Nucleosynthesis ,Galactic evolution ,Nuclear Astrophysics ,Astrophysics::Solar and Stellar Astrophysics ,Neutron ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Physics ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Interstellar medium ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Earth and Planetary Astrophysics ,s-process ,Open cluster - Abstract
Recent spectroscopic measurements in open clusters younger than the Sun, with [Fe/H]>=0, showed that the abundances of neutron-rich elements have continued to increase in the Galaxy after the formation of the Sun, roughly maintaining a solar-like distribution. Such a trend requires neutron fluences larger than those so far assumed, as these last would have too few neutrons per iron seed. We suggest that the observed enhancements can be produced by nucleosynthesis in AGB stars of low mass (M < 1.5M\odot), if they release neutrons from the ^{13}C(��,n)^{16}O reaction in reservoirs larger by a factor of 4 than assumed in more massive AGBs (M > 1.5M\odot). Adopting such a stronger neutron source as a contributor to the abundances at the time of formation of the Sun, we show that this affects also the solar s-process distribution, so that its main component is well reproduced, without the need of assuming ad-hoc primary sources for the synthesis of s elements up to A \sim 130, contrary to suggestions from other works. The changes in the expected abundances that we find are primarily due to the following reasons. i) Enhancing the neutron source increases the efficiency of the s process, so that the ensuing stellar yields now mimic the solar distribution at a metallicity higher than before ([Fe/H]>=-0.1). ii) The age-metallicity relation is rather flat for several Gyr in that metallicity regime, so that those conditions remain stable and the enhanced nuclear yields, which are necessary to maintain a solar-like abundance pattern, can dominate the composition of the interstellar medium from which subsequent stars are formed., Accepted for publication in The Astrophysical Journal
- Published
- 2011
19. Introduction to the s-process
- Author
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Enrico Maiorca, Maurizio Busso, Sara Palmerini, Sofia Randich, and Laura Magrini
- Subjects
Engineering ,business.industry ,business ,Management - Published
- 2011
20. Mass loss and luminosities of S and C AGB stars with and without Li
- Author
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Enrico Maiorca, Maurizio Busso, R. Guandalini, Stefan Uttenthaler, and Sara Palmerini
- Subjects
Physics ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Spectral line ,Galaxy ,Stellar wind ,Stars ,Space and Planetary Science ,Stellar mass loss ,Infrared Spectrophotometry ,Astrophysics::Solar and Stellar Astrophysics ,Asymptotic giant branch ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We present the preliminary results of an analysis performed on two samples of thermally pulsing Asymptotic Giant Branch stars from our Galaxy, the first made of carbon-rich sources and the second of S-type stars. We have estimated their absolute luminosities and updated rates of the stellar winds through methods based on their infrared spectrophotometry and on updated estimates of their variability and distance.We then focus on those sources in our database showing Li in their spectra looking for correlations between the Li abundance and the other physical parameters, in the aim of establishing observational criteria for understanding the conditions for the occurrence of the deep mixing phenomena to which the production of Li is currently attributed.
- Published
- 2010
21. Open clusters towards the Galactic centre: chemistry and dynamics.A VLT spectroscopic study of NGC 6192, NGC 6404, NGC 6583
- Author
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Giovanni Carraro, Enrico Maiorca, Sofia Randich, Lucie Jílková, Daniele Galli, Manuela Zoccali, Maurizio Busso, and Laura Magrini
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Cepheid variable ,Metallicity ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Context (language use) ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,open clusters and associations: individual: NGC 6192 ,0103 physical sciences ,Galaxy formation and evolution ,Astrophysics::Solar and Stellar Astrophysics ,Galaxy: abundances ,Galaxy: evolution ,open clusters and associations: individual: NGC 6404 ,open clusters and associations: individual: NGC 6583 ,Physics::Chemical Physics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Physics ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Stars ,Star cluster ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Earth and Planetary Astrophysics ,Open cluster ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
In the framework of the study of the Galactic metallicity gradient and its time evolution, we present new high-resolution spectroscopic observations obtained with FLAMES and the fiber link to UVES at VLT of three open clusters (OCs) located within $\sim$7~kpc from the Galactic Center (GC): NGC~6192, NGC~6404, NGC~6583. We also present new orbit determination for all OCs with Galactocentric distances (R$_{\rm{GC}}) \leq$8~kpc and metallicity from high-resolution spectroscopy. We aim to investigate the slope of the inner disk metallicity gradient as traced by OCs and at discussing its implication on the chemical evolution of our Galaxy. We have derived memberships of a group of evolved stars for each clusters, obtaining a sample of 4, 4, and 2 member stars in NGC~6192, NGC~6404, and NGC~6583, respectively. Using standard LTE analysis we derived stellar parameters and abundance ratios for the iron-peak elements Fe, Ni, Cr, and for the $\alpha$-elements Al, Mg, Si, Ti, Ca. We calculated the orbits of the OCs currently located within 8~kpc from the GC, and discuss their implication on the present-time radial location. {The average metallicities of the three clusters are all oversolar: [Fe/H]= $+0.12\pm0.04$ (NGC~6192), $+0.11\pm0.04$ (NGC 6404), $+0.37\pm0.03$ (NGC 6583). They are in qualitative agreement with their Galactocentric distances, being all internal OCs, and thus expected to be metal richer than the solar neighborhood. The abundance ratios of the other elements over iron [X/Fe] are consistent with solar values. The clusters we have analysed, together with other OC and Cepheid data, confirm a steep gradient in the inner disk, a signature of an evolutionary rate different than in the outer disk., Comment: 17 pages, 13 figures, A&A accepted for publication
- Published
- 2010
22. Extra-mixing in red giant stars: Challenges for nuclear physics
- Author
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Enrico Maiorca and Sara Palmerini
- Subjects
Physics ,History ,Red giant ,Electron capture ,Astronomy ,Astrophysics ,Computer Science Applications ,Education ,Magnetic field ,Reaction rate ,Nuclear physics ,Stars ,Yield (chemistry) ,Astrophysics::Solar and Stellar Astrophysics ,Low Mass ,Astrophysics::Galaxy Astrophysics ,Mixing (physics) - Abstract
The existence of extra-mixing phenomena has been often invoked as a possible solution for the Li-abundance puzzle in low-mass red giant stars. In particular, [1] have shown that extra-mixing phenomena induced by stellar magnetic fields can justify the surface Li enrichment as well as its depletion in low mass giants. In the framework of this model, we test here how sensitive is the Li production to the reaction rate for the 7Be electron capture, in order to establish whether the presence of intense magnetic fields can alter the Li yield.
- Published
- 2010
23. Nucleosynthesis of light element isotopes in evolved stars experiencing extended mixing
- Author
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Enrico Maiorca, R. Guandalini, Maurizio Busso, and Sara Palmerini
- Subjects
deep mixing ,Buoyancy ,Population ,FOS: Physical sciences ,Astrophysics ,engineering.material ,Nucleosynthesis ,Asymptotic giant branch ,Astrophysics::Solar and Stellar Astrophysics ,education ,Mixing (physics) ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Physics ,education.field_of_study ,stellar evolution ,Isotope ,red giants ,Presolar grains ,nucleosynthesis ,Astronomy and Astrophysics ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,engineering - Abstract
We present computations of nucleosynthesis in red giants and asymptotic giant branch stars of Population I experiencing extended mixing. The assumed physical cause for mass transport is the buoyancy of magnetized structures, according to recent suggestions. The peculiar property of such a mechanism is to allow for both fast and slow mixing phenomena, as required for reproducing the spread in Li abundances displayed by red giants and as discussed in an accompanying paper. We explore here the effects of this kind of mass transport on CNO and intermediatemass nuclei and compare the results with the available evidence from evolved red giants and from the isotopic composition of presolar grains of AGB origin. It is found that a good general accord exists between predictions and measurements; in this framework we also show which type of observational data best constrains the various parameters. We conclude that magnetic buoyancy, allowing for mixing at rather different speeds, can be an interesting scenario to explore for explaining together the abundances of CNO nuclei and of Li., 8 pages, 7 figures, proceeding of 'The Origin of the Elements Heavier than Fe' September 24-28, 2008, Torino, Italy. PASA (accepted for publication)
- Published
- 2009
24. The solar photospheric nitrogen abundance Analysis of atomic transitions with 3D and 1D model atmospheres
- Author
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Elisabetta Caffau, Inga Kamp, Piercarlo Bonifacio, Enrico Maiorca, Matthias Steffen, Maurizio Busso, H.-G. Ludwig, R. Faraggiana, and Astronomy
- Subjects
astro-ph.SR ,010504 meteorology & atmospheric sciences ,stars: abundances ,Metallicity ,Solar Physics ,FOS: Physical sciences ,Context (language use) ,Astrophysics ,01 natural sciences ,7. Clean energy ,Spectral line ,OXYGEN ,Solar chemical ,Abundance (ecology) ,SEPARATION RATIOS ,0103 physical sciences ,ELEMENTS ,Astrophysics::Solar and Stellar Astrophysics ,STATISTICAL EQUILIBRIUM ,Helioseismology ,Sun: abundances ,DEGREE P-MODES ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,GRANULATION ,0105 earth and related environmental sciences ,Physics ,Standard solar model ,SPECTRUM ,LINE FORMATION ,Solar Abundances ,Astronomy and Astrophysics ,Solar Photosperes ,Cosmic Abundances ,HYDROGEN ,HELIOSEISMOLOGY ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,Physics::Space Physics ,hydrodynamics ,Astrophysics::Earth and Planetary Astrophysics ,line: formation ,Equivalent width - Abstract
CONTEXT: In recent years, the solar chemical abundances have been studied in considerable detail because of discrepant values of solar metallicity inferred from different indicators, i.e., on the one hand, the "sub-solar" photospheric abundances resulting from spectroscopic chemical composition analyses with the aid of 3D hydrodynamical models of the solar atmosphere, and, on the other hand, the high metallicity inferred by helioseismology. AIMS: After investigating the solar oxygen abundance using a CO5BOLD 3D hydrodynamical solar model in previous work, we undertake a similar approach studying the solar abundance of nitrogen, since this element accounts for a significant fraction of the overall solar metallicity, Z. METHOD: We used a selection of atomic spectral lines to determine the solar nitrogen abundance, relying mainly on equivalent width measurements in the literature. We investigate the influence on the abundance analysis, of both deviations from local thermodynamic equilibrium ("NLTE effects") and photospheric inhomogeneities ("granulation effects"). RESULTS: We recommend use of a solar nitrogen abundance of A(N)=7.86+-0.12 whose error bar reflects the line-to-line scatter. CONCLUSION: The solar metallicity implied by the CO5BOLD-based nitrogen and oxygen abundances is in the range 0.0145, To be published on A&A
- Published
- 2009
25. Li and CNO isotopes from magnetically induced extra-mixing in evolved stars
- Author
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Maurizio Busso, Sara Palmerini, Enrico Maiorca, and R. Guandalini
- Subjects
Physics ,Buoyancy ,Proton ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,engineering.material ,T Tauri star ,Stars ,Space and Planetary Science ,Stellar mass loss ,engineering ,Low Mass ,Main sequence ,Mixing (physics) - Abstract
Evolved low mass stars (LMS) contribute not only to the synthesis of s-process nuclei, but also to modifications in the isotopic mix of light elements (Li and CNO especially), induced by proton captures. In particular, RGB and AGB stars show a wide range of Li abundances. This spread is currently attributed to deep phenomena of non-convective mixing. These processes can, in principle, either produce or destroy Li, depending on their velocity. This is due to the fact that Li production requires preserving the unstable 7Be, which has a half-life of only 53 days. Physical mechanisms devised so far to explain the existence of deep mixing in low mass stars generally fail in accounting for fast transport and in avoiding 7Be destruction; on the contrary, this is easily obtained in Intermediate Mass Stars, where Hot Bottom Burning can occur. However, as Li-rich low-mass red giants do exist, we propose here a scenario where both production and destruction of Li are possible in LMS, thanks to the buoyancy of magnetized parcels of processed matter, traveling from the H shell to the envelope at different speeds (depending on their size). Consequences of this transport for CNO nuclei are also discussed.
- Published
- 2009
26. On a physical model for the formation of the neutron source for s-processing
- Author
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Sara Palmerini, Enrico Maiorca, Oscar Trippella, Maurizio Busso, Laura Magrini, and Sofia Randich
- Subjects
Nuclear physics ,Physics ,Neutron source
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