KORDOPATIS , G.

Context. Large spectroscopic Galactic surveys imply a selection function in the way they performed their target selection. Aims. We investigate here the effect of the selection function on the metallicity distribution function (MDF) and on the vertical metallicity gradient by studying similar lines of sight using four different spectroscopic...

Multi-fibre spectrographs have made possible the run of large spectroscopic surveys targeting 10^5 to millions of Milky Way (MW) stars. The targeted stars belong to the main stellar structures of our Galaxy and mostly sample stellar evolutionary stages from the (pre-)main-sequence to the red giant branch. Their primary aim is to harvest a vast...

International audience

Context. The abundance of α-elements relative to iron ([α/Fe]) is an important fossil signature in Galactic archaeology for tracing the chemical evolution of disc stellar populations. High-precision chemical abundances, together with accurate stellar ages, distances, and dynamical data, are crucial to infer the Milky Way formation history.Aims:...

International audience

International audience

Context. Diffuse interstellar bands (DIBs) are important interstellar absorption features of which the origin is still debated. With the large data sets from modern spectroscopic surveys, background stars are widely used to show how the integrated columns of DIB carriers accumulate from the Sun to great distances. To date, studies on the...

Not Available

Aims: We test the performance of the semi-analytic self-consistent Just-Jahreiß disc model (JJ model) with the astrometric data from the Tycho-Gaia Astrometric Solution (TGAS) sub-catalogue of the first Gaia data release (Gaia DR1), as well as the radial velocities from the fifth data release of the Radial Velocity Experiment survey (RAVE DR5)....

Context. Sulfur is a volatile chemical element that plays an important role in tracing the chemical evolution of the Milky Way and external galaxies. However, its nucleosynthesis origin and abundance variations in the Galaxy are still unclear because the number of available stellar sulfur abundance measurements is currently rather small.Aims....

Context. Diffuse interstellar bands (DIBs) are interstellar absorption features that widely exist in the optical and near-infrared wavelength range. DIBs play an important role in the lifecycle of the interstellar medium and can also be used to trace the Galactic structure.Aims. We developed a set of procedures to automatically detect and...

Context. Diffuse interstellar bands (DIBs) are interstellar absorption features that widely exist in the optical and near-infrared wavelength range. DIBs play an important role in the lifecycle of the interstellar medium and can also be used to trace the Galactic structure.Aims. We developed a set of procedures to automatically detect and...

Reliable stellar age estimates are fundamental for testing several problems in modern astrophysics, in particular since they set the time scales of Galactic dynamical and chemical evolution. In this study, we determine ages using only Gaia DR3 photometry and parallaxes, in combination with interstellar extinction maps, spectroscopic...

International audience

After the second data release of Gaia, the number of new globular cluster candidates has increased importantly. However, most of them need to be properly characterised, both spectroscopically and photometrically, by means of radial velocities, metallicities, and deeper photometric observations. Our goal is to provide an independent confirmation...