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The Gaia-ESO Survey: the chemical structure of the Galactic discs from the first internal data release

Mikolaitis, S.; Hill, V.; Recio-Blanco, A.; de laverny, P.; Allende Prieto, C.; Kordopatis, G.; Tautvaisiene, G.; Romano, D.; Gilmore, G. and Randich, S., et al. (2014) In Astronomy & Astrophysics 572.
Abstract
Aims. Until recently, most high-resolution spectroscopic studies of the Galactic thin and thick 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 the thin and thick discs, using the first internal data release of the Gaia-ESO survey (GES iDR1). Methods. We used the spectra of around 2000 FGK dwarfs and giants from the GES iDR1, obtained at resolutions of up to R similar to 20 000 with the FLAMES/GIRAFFE spectrograph. We derive and discuss the abundances of eight elements (Mg, Al, Si, Ca, Ti, Fe, Cr, Ni, and Y). Results. We show that the trends of these elemental abundances with iron are very similar to those in the solar... (More)
Aims. Until recently, most high-resolution spectroscopic studies of the Galactic thin and thick 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 the thin and thick discs, using the first internal data release of the Gaia-ESO survey (GES iDR1). Methods. We used the spectra of around 2000 FGK dwarfs and giants from the GES iDR1, obtained at resolutions of up to R similar to 20 000 with the FLAMES/GIRAFFE spectrograph. We derive and discuss the abundances of eight elements (Mg, Al, Si, Ca, Ti, Fe, Cr, Ni, and Y). Results. We show that 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. This separation is visible for most alpha-elements and for aluminium. 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 the first paper from this series for our sample, 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 (4 to 12 kpc) and vertical (0 to 3.5 kpc) gradients in metallicity, iron, four alpha-element abundances, and aluminium for the two populations, taking into account the identified correlation between R-GC and vertical bar Z vertical bar. Similarly to other works, a 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 in the solar cylinder, accompanied by positive individual [alpha/M] and [Al/M] gradients. The thick-disc, on the other hand, 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. We examine several thick-disc formation scenarii in the light of these radial and vertical trends. (Less)
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Galaxy: disk, Galaxy: stellar content, techniques: spectroscopic
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Astronomy & Astrophysics
volume
572
publisher
EDP Sciences
external identifiers
  • wos:000346101700049
  • scopus:84912140823
ISSN
0004-6361
DOI
10.1051/0004-6361/201424093
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English
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259c9c83-1633-4724-b365-0dab6bc63c28 (old id 4944624)
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2015-01-28 11:51:16
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@article{259c9c83-1633-4724-b365-0dab6bc63c28,
  abstract     = {Aims. Until recently, most high-resolution spectroscopic studies of the Galactic thin and thick 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 the thin and thick discs, using the first internal data release of the Gaia-ESO survey (GES iDR1). Methods. We used the spectra of around 2000 FGK dwarfs and giants from the GES iDR1, obtained at resolutions of up to R similar to 20 000 with the FLAMES/GIRAFFE spectrograph. We derive and discuss the abundances of eight elements (Mg, Al, Si, Ca, Ti, Fe, Cr, Ni, and Y). Results. We show that 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. This separation is visible for most alpha-elements and for aluminium. 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 the first paper from this series for our sample, 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 (4 to 12 kpc) and vertical (0 to 3.5 kpc) gradients in metallicity, iron, four alpha-element abundances, and aluminium for the two populations, taking into account the identified correlation between R-GC and vertical bar Z vertical bar. Similarly to other works, a 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 in the solar cylinder, accompanied by positive individual [alpha/M] and [Al/M] gradients. The thick-disc, on the other hand, 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. We examine several thick-disc formation scenarii in the light of these radial and vertical trends.},
  articleno    = {A33},
  author       = {Mikolaitis, S. and Hill, V. and Recio-Blanco, A. and de laverny, P. and Allende Prieto, C. and Kordopatis, G. and Tautvaisiene, G. and Romano, D. and Gilmore, G. and Randich, S. and Feltzing, Sofia and Micela, G. and Vallenari, A. and Alfaro, E. J. and Bensby, Thomas and Bragaglia, A. and Flaccomio, E. and Lanzafame, A. C. and Pancino, E. and Smiljanic, R. and Bergemann, M. and Carraro, G. and Costado, M. T. and Damiani, F. and Hourihane, A. and Jofre, P. and Lardo, C. and Magrini, L. and Maiorca, E. and Morbidelli, L. and Sbordone, L. and Sousa, S. G. and Worley, C. C. and Zaggia, S.},
  issn         = {0004-6361},
  keyword      = {Galaxy: disk,Galaxy: stellar content,techniques: spectroscopic},
  language     = {eng},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {The Gaia-ESO Survey: the chemical structure of the Galactic discs from the first internal data release},
  url          = {http://dx.doi.org/10.1051/0004-6361/201424093},
  volume       = {572},
  year         = {2014},
}