Foreground Galactic stars properties

DOI

We study the chemical and kinematic properties of roughly a thousand FLAMES-GIRAFFE LR8 spectra of faint magnitude foreground Galactic stars observed serendipitously during extra-galactic surveys in four lines-of-sight: three in the southern Galactic hemisphere (surveys of the Carina, Fornax and Sculptor dwarf spheroidal galaxies) and one in the northern Galactic hemisphere (a survey of the Sextans dwarf spheroidal galaxy). The foreground stars span distances up to ~3kpc from the Galactic plane and Galactocentric radii up to 11kpc. The stellar atmospheric parameters (effective temperature, surface gravity, metallicity) are obtained by an automated parameterisation pipeline and the distances of the stars are then derived by a projection of the atmospheric parameters on a set of theoretical isochrones using a Bayesian approach. The metallicity gradients are estimated for each line-of-sight and compared with predictions from the Besancon model of the Galaxy, in order to test the chemical structure of the thick disc. Finally, we use the radial velocities in each line-of-sight to derive a proxy for either the azimuthal or the vertical component of the orbital velocity of the stars. Only three lines-of-sight have a sufficient number of foreground stars for a robust analysis. Towards Sextans in the Northern Galactic hemisphere and Sculptor in the South, we measure a consistent decrease in mean metallicity with height from the Galactic plane, suggesting a chemically symmetric thick disc. This decrease can either be due to an intrinsic thick disc metallicity gradient, or simply due to a change in the thin disc/thick disc population ratio and no intrinsic metallicity gradients for the thick disc. We favour the latter explanation. In contrast, we find evidence of an unpredicted metal-poor population in the direction of Carina. This population was earlier detected by Wyse et al. (2006ApJ...639L..13W), but our more detailed analysis provides robust estimates of its location (|Z|<1kpc), metallicity (-2<[M/H]<-1dex) and azimuthal orbital velocity (V_phi_~120km/s).

Cone search capability for table J/A+A/555/A12/stars (Atmospheric parameters, positions, radial velocities, magnitudes and distances of the selected faint foreground galactic stars)

Identifier
DOI http://doi.org/10.26093/cds/vizier.35550012
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/A+A/555/A12
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/555/A12
Related Identifier https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/555/A12
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/A+A/555/A12
Provenance
Creator Kordopatis G.; Hill V.; Irwin M.; Gilmore G.; Wyse R.F.G.; Tolstoy E.,de Laverny P.; Recio-Blanco A.; Battaglia G.; Starkenburg E.
Publisher CDS
Publication Year 2013
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Exoplanet Astronomy; Galactic and extragalactic Astronomy; Interdisciplinary Astronomy; Natural Sciences; Observational Astronomy; Physics