I summarize two recent projects involving the Gaia-TGAS data. Firstly, I discuss a detection of a lack of disc stars in the Solar neighbourhood with velocities close to zero angular momentum. We use predictions of this effect to make a measurement of the Solar rotation velocity around the Galactic centre, and also of R 0. Secondly, I discuss a detection of a group of stars with systematically high Galactic rotation velocity. We propose that it may be caused by the Perseus arm and compare the data with simulations.

Angle/action based distribution function (DF) models can be optimised based on how well they reproduce observations thus revealing the current matter distribution in the Milky Way. Gaia data combined with data from other surveys, e.g. the RAVE/TGAS sample, and its full selection function will greatly improve their accuracy.

We present a model to map the 3D distribution of dust in the Milky Way. Although dust is just a tiny fraction of what comprises the Galaxy, it plays an important role in various processes. In recent years various maps of dust extinction have been produced, but we still lack a good knowledge of the dust distribution. Our presented approach leverages line-of-sight extinctions towards stars in the Galaxy at measured distances. Since extinction is proportional to the integral of the dust density towards a given star, it is possible to reconstruct the 3D distribution of dust by combining many lines-of-sight in a model accounting for the spatial correlation of the dust. Such a technique can be used to infer the most probable 3D distribution of dust in the Galaxy even in regions which have not been observed. This contribution provides one of the first maps which does not show the “fingers of God” effect. Furthermore, we show that expected high precision measurements of distances and extinctions offer the possibility of mapping the spiral arms in the Galaxy.

The extended observational program for study of cataclysmic variables is realized in Sternberg Astronomical Institute during the last years. A few telescopes of Crimean Observational Station equipped with a different devices, — UBV photometer and two CCD camera, are used for observations. Among the close binary systems (CBS), cataclysmic variables are the most interesting objects because of the outburst activity and variety of their observational features. They could serve a good laboratory for study of physical processes in CBS. GAIA provides astronomers with a new ample opportunity for investigation of cataclysmic variables. Though the relative faintness of detected objects it is still possible to carry out a high accuracy ground-based observations with our equipment. Obtained ground-based data permit us to confirm classification of detected CV-candidates, to determine the physical characteristics with a sample of new cods and improve the current understanding of their nature.

Hypervelocity stars (HVSs) are characterized by a total velocity in excess of the Galactic escape speed, and with trajectories consistent with coming from the Galactic Centre. We apply a novel data mining routine, an artificial neural network, to discover HVSs in the TGAS subset of the first data release of the Gaia satellite, using only the astrometry of the stars. We find 80 stars with a predicted probability >90% of being HVSs, and we retrieved radial velocities for 47 of those. We discover 14 objects with a total velocity in the Galactic rest frame >400 km s−1, and 5 of these have a probability >50% of being unbound from the Milky Way. Tracing back orbits in different Galactic potentials, we discover 1 HVS candidate, 5 bound HVS candidates, and 5 runaway star candidates with remarkably high velocities, between 400 and 780 km s−1. We wait for future Gaia releases to confirm the goodness of our sample and to increase the number of HVS candidates.

Our recent studies based on a large sample of K giants with Hipparcos parallaxes and spectroscopic analysis resulted more than a dozen new Li-rich K giants including few super Li-rich ones. Most of the Li-rich K giants including the new ones appear to occur at the luminosity bump in the HR diagram. However, one can’t rule out the possibility of overlap with the clump region where core He-burning K giants reside post He-flash at the tip of RGB. It is important to distinguish field K giants of clump from the bump region in the HR diagram to understand clues for Li production in K giants. In this poster, we explore whether GAIA parallaxes improve to disentangle clump from bump region, more precisely.

Comets in the Oort cloud evolve under the influence of internal and external perturbations from giant planets to stellar passages, the Galactic tides, and the interstellar medium.Using the positions, parallaxes and proper motions from TGAS in Gaia DR1 and combining them with the radial velocities from the RAVE-DR5, Geneva-Copenhagen and Pulkovo catalogues, we calculated the closest encounters the Sun has had with other stars in the recent past and will have in the near future. We find that the stars with high proper motions near to the present time are missing in the Gaia-TGAS, and those to tend to be the closest ones. The quality of the data allows putting better constraints on the encounter parameters, compared to previous surveys.

The Gaia-ESO survey (GES; Gilmore et al. (2012), Randich et al. (2013)) is a spectroscopic survey complementing the Gaia mission to bring accurate radial velocities and chemical abundances for 105 stars. Merle et al. (submitted to A&A; see also this volume) developped a tool (DOE) to detect multiple peaks in the cross-correlation functions (CCFs) of GES spectra. Using the GIRAFFE HR10 and HR21 settings, we were able to compare the efficiency of our SB detection tool depending on the wavelength range and resolution. We show that a careful design of CCF masks can improve the detection rate in the HR21 settings. HR21 spectra are similar to the ones produced by the RVS spectrograph of the Gaia mission, though the lower resolution of RVS spectra may result in a lower detection efficiency than the case of HR21. Analysis of RVS spectra in the context of spectroscopic binaries can take advantage of the lessons learnt from the GES to maximize the detection rate.

The vast majority of stars will become white dwarfs at the end of the stellar life cycle. These remnants are precise cosmic clocks owing to their well constrained cooling rates. Gaia Data Release 2 is expected to discover hundreds of thousands of white dwarfs, which can then be observed spectroscopically with WEAVE and 4MOST. By employing spectroscopically derived atmospheric parameters combined with Gaia parallaxes, white dwarfs can constrain the stellar formation history in the early developing phases of the Milky Way, the initial mass function in the 1.5 to 8 M ⊙ range, and the stellar mass loss as well as the state of planetary systems during the post main-sequence evolution.

Chemical evolution of r-process elements in the Milky Way disc is still a matter of debate. We took advantage of high resolution HARPS spectra from the ESO archive in order to derive precise chemical abundances of 3 r-process elements Eu, Dy & Gd for a sample of 4 355 FGK Milky Way stars. The chemical analysis has been performed thanks to the automatic optimization pipeline GAUGUIN. Based on the [α/Fe] ratio, we chemically characterized the thin and the thick discs, and present here results of these 3 r-process element abundances in both discs. We found an unexpected Gadolinium and Dysprosium enrichment in the thick disc stars compared to Europium, while these three elements track well each other in the thin disc.

We use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalog to date, to study the evolution of the kinematical properties of the population of white dwarfs in the Galactic disc. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalog are available the true three-dimensional components of the stellar space velocity are obtained. This subset of the original sample comprises 20,247 objects, making it the largest sample of white dwarfs with measured three-dimensional velocities. Furthermore, the volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance R G = 7.8 kpc to 9.3 kpc, and vertical distances from the Galactic plane ranging from Z = −0.5 kpc to 0.5 kpc. We examine the mean components of the stellar three-dimensional velocities, as well as their dispersions with respect to the Galactocentric and vertical distances. We confirm the existence of a mean Galactocentric radial velocity gradient, ∂〈V R〉/∂R G = −3 ± 5 km s−1 kpc−1. We also confirm North-South differences in 〈V z〉. Specifically, we find that white dwarfs with Z > 0 (in the North Galactic hemisphere) have 〈V z〉 < 0, while the reverse is true for white dwarfs with Z < 0. The age-velocity dispersion relation derived from the present sample indicates that the Galactic population of white dwarfs may have experienced an additional source of heating, which adds to the secular evolution of the Galactic disc.

One of the ways to obtain a detailed 3D ISM map is by gathering interstellar (IS) absorption data toward widely distributed background target stars at known distances (line-of-sight/LOS data). The radial and angular evolution of the LOS measurements allow the inference of the ISM spatial distribution. For a better spatial resolution, one needs a large number of the LOS data. It requires building fast tools to measure IS absorption. One of the tools is a global analysis that fit two different diffuse interstellar bands (DIBs) simultaneously. We derived the equivalent width (EW) ratio of the two DIBs recorded in each spectrum of target stars. The ratio variability can be used to study IS environmental conditions or to detect DIB family.

Regular astrometric observations of small bodies of the Solar System are conducted using a SBG telescope of the Kourovka Astronomical Observatory of the Ural Federal University. The first results of participation in Gaia-FUN-SSO network are presented.

Stellar clusters are important for astrophysics in many ways, for instance as optimal tracers of the Galactic populations to which they belong or as one of the best test bench for stellar evolutionary models. Gaia DR1, with TGAS, is just skimming the wealth of exquisite information we are expecting from the more advanced catalogues, but already offers good opportunities and indicates the vast potentialities. Gaia results can be efficiently complemented by ground-based data, in particular by large spectroscopic and photometric surveys. Examples of some scientific results of the Gaia-ESO survey are presented, as a teaser for what will be possible once advanced Gaia releases and ground-based data will be combined.

Gaia DR1 was released in September 2016 and contained a photometric catalogue of over 1 billion sources. At this stage, this only included mean G-band photometry and an estimate of the error. Even though this may sound limited in nature, interesting science can still be achieved with this data thanks to its quality. A high level overview of the photometric processing and some validation results will be presented. Additionally, epoch photometry in the G-band was released in Gaia DR1 for a small number of variable sources in the South Ecliptic Pole which covers the LMC. The second data release (Gaia DR2) is currently being prepared and, if available, some preliminary validation results will be presented. It is planned that this release will contain colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry.

The nature and origin of the Galactic warp represent one of the open questions posed by Galactic evolution. Thanks to Gaia high precision absolute astrometry, steps towards the understanding of the warp's dynamical nature can be made. Indeed, proper motions for long-lived stable warp are expected to show measurable trends in the component vertical to the galactic plane. Within this context, we search for the kinematic warp signal in the first Gaia data release (DR1). By analyzing distant spectroscopically-identified OB stars in the Hipparcos subset in Gaia DR1, we find that the kinematic trends cannot be explained by a simple model of a long-lived warp. We therefore discuss possible scenarios for the interpretation of the obtained results. We also present current work in progress to select a larger sample of OB star candidates from the Tycho-Gaia Astrometric Solution (TGAS) subsample in DR1, and delineate the points that we will be addressing in the near future.

Classical variables like RR Lyrae, classical and Type-II Cepheids and Mira variables all follow period-luminosity relations that make them interesting as distance indicators. Especially the RR Lyrae and δ Cepheids are crucial in establishing the distance scale in the Universe, and all classes of variables can be used as tracers of galactic structure. I will present an overview of recent period-luminosity relations and review the work that has been done using the Gaia DR1 data so far, and discuss possibilities for the future.

Stellar occultations by solar system objects allow kilometric accuracy, permit the detection of tenuous atmospheres (at nbar level), and the discovery of rings. The main limitation was the prediction accuracy, typically 40 mas, corresponding to about 1,000 km projected at the body. This lead to large time dedicated to astrometry, tedious logistical issues, and more often than not, mere miss of the event. The Gaia catalog, with sub-mas accuracy, hugely improves both the star positions, resulting in achievable accuracies of about 1 mas for the shadow track on Earth. This permits much more carefully planned campaigns, with success rate approaching 100%, weather permitting. Scientific perspectives are presented, e.g. central flashes caused by Plutos atmosphere revealing hazes and winds near its surface, grazing occultations showing topographic features, occultations by Chariklos rings unveiling dynamical features such as proper mode “breathing”.

We present a catalog of potential candidates for asteroid mass determination based on mutual close encounters of numbered asteroids with massive perturbers (D>20 km). Using a novel geometric approach tuned to optimize observability, we predict optimal epochs for mass determination observations. In contrast to previous studies that often used simplified dynamical models, we have numerically propagated the trajectories of all numbered asteroids over the time interval from 2013 to 2023 using relativistic equations of motion including planetary perturbations, J2 of the Sun, the 16 major asteroid perturbers and the perturbations due to non-sphericities of the planets. We compiled a catalog of close encounters between asteroids where the observable perturbation of the sky plane trajectory is greater than 0.5 mas so that astrometric measurements of the perturbed asteroids in the Gaia data can be leveraged. The catalog v1.0 is available at ftp://dosya.akdeniz.edu.tr/ivantsov.

The ESA-PLATO 2.0 mission will perform an in-depth analysis of the large part of the sky-sphere searching for extraterrestrial telluric-like planets. At the Molėtai Astronomical Observatory of Vilnius University, we started a spectroscopic and photometric survey of the northern sky fields that potentially will be targeted by the PLATO mission. We aim to contribute in developing the PLATO input catalogue by delivering a long-duration stellar variability information and a full spectroscopic characterization of brightest targets. First results of this survey are overviewed.