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The Gaia-ESO Survey: New constraints on the Galactic disc velocity dispersion and its chemical dependencies

Guiglion, G and Recio-Blanco, A and de Laverny, P and Kordopatis, G and Hill, V and Mikolaitis, S and Minchev, I and Chiappini, C and Wyse, RFG and Gilmore, G and Randich, S and Feltzing, S and Bensby, T and Flaccomio, E and Koposov, SE and Pancino, E and Bayo, A and Costado, MT and Franciosini, E and Hourihane, A and Jofre, P and Lardo, C and Lewis, J and Lind, K and Magrini, L and Morbidelli, L and Sacco, GG and Ruchti, G and Worley, CC and Zaggia, S (2015) The Gaia-ESO Survey: New constraints on the Galactic disc velocity dispersion and its chemical dependencies. Astronomy and Astrophysics, 583. ISSN 0004-6361

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Abstract

Context. Understanding the history and the evolution of the MilkyWay is one of the main goals of modern astrophysics. In particular, the formation of the Galactic disc is a key problem of Galactic archaeology.
Aims.We study the velocity dispersion behaviour of Galactic disc stars as a function of the [Mg=Fe] ratio, which for small metallicity bins can be used as a proxy of relative age. This key relation is essential to constrain the formation mechanisms of the disc stellar populations as well as the cooling and settling processes.
Methods. We used the recommended parameters and chemical abundances of 7800 FGK Milky Way field stars from the second internal data release of the Gaia-ESO spectroscopic Survey. These stars were observed with the GIRAFFE spectrograph (HR10 and
HR21 setups), and cover a large spatial volume in the intervals 6 < R < 10 kpc and jZj < 2 kpc. Based on a chemical criterion, we separated the thin- from the thick-disc sequence in the [Mg=Fe] vs: [Fe=H] plane.
Results. From analysing the Galactocentric velocity of the stars for the thin disc, we find a weak positive correlation between V_ and [Fe=H] that is due to a slowly rotating [Fe=H]-poor tail. For the thick disc stars, a strong correlation with [Fe=H] and [Mg=Fe] is established. In addition, we have detected an inversion of the velocity dispersion trends with [Mg=Fe] for thick-disc stars with [Fe=H] <

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: EDP Sciences
Related URLs:
Date Deposited: 22 Nov 2016 12:24
Last Modified: 07 Sep 2017 00:43
DOI or Identification number: 10.1051/0004-6361/201525883
URI: http://researchonline.ljmu.ac.uk/id/eprint/4838

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