We perform realistic simulations of the Sun's birth cluster in order to predict the current distribution of solar siblings in the Galaxy. We study the possibility of finding the solar siblings in the Gaia catalogue by using only positional and kinematic information. We find that the number of solar siblings predicted to be observed by Gaia will be around 100 in the most optimistic case, and that a phase space only search in the Gaia catalogue will be extremely difficult. It is therefore mandatory to combine the chemical tagging technique with phase space selection criteria in order to have any hope of finding the solar siblings.

We present stellar parameters, stellar ages, and detailed elemental abundances for Na, Mg, Al, Si, Ca, Ti, Cr, Fe, and Ni for 32 solar sibling candidates. Technique of chemical tagging gives us a high probability that four stars might be from the same open cluster. Only one candidate HIP 40317 which has solar metallicity and age could be a solar sibling. We performed simulations of the Sun's birth cluster in analytical Galactic model and found that there is quite low probability to find solar siblings with radial velocity up to Vr = 34.2 km s−1.

Past studies have already shown that stars in open clusters are chemically homogeneous (e.g. De Silva et al. 2006, 2007 and 2009). These results support the idea that stars born from the same giant molecular cloud should have the same chemical composition. In this context, the chemical tagging technique was proposed by Freeman et al. (2002). The principle is to recover disrupted stellar clusters by looking only to the stellar chemical composition. In order to evaluate the feasibility of this approach, it is necessary to test if we can distinguish between stars born from different molecular clouds. For this purpose, we studied the chemical composition of stars in 32 old and intermediate-age open clusters, and we applied machine learning algorithms to recover the original cluster by only considering the chemical signatures.

We study the role of radial migration of stars on the chemical evolution of the Milky Way disk with a 1D semi-analytical disk model. We describe radial migration with parametrised time- and radius-dependent diffusion coefficients, based on the analysis of a N-body+SPH simulation of a disk galaxy (analyzed by Kubryk et al. 2013). Our model reproduces well the present day values of most of the main global observables of the MW. Assuming that the thick disk is the oldest (>9 Gyr) part of the disk, we find that the adopted radial migration scheme can reproduce quantitatively the main local properties of the thin and thick disk: metallicity-distributions, dispersion in age-metallicity relation, “two-branch” behaviour in the O/Fe vs. Fe/H relation, local surface densities of stars, etc..

Lincoln Near-Earth Asteroid Research asteroid survey (LINEAR) observed proximately 10,000 deg2 of the northern sky in period roughly from 1998 to 2013. Long baseline of observations combined with good cadence and depth (14.5 < rSDSS < 17.5) provides excellent basis for investigation of variable and transient objects in this relatively faint and underexplored part of the sky. Details covering the repurposing of this survey for use in time domain astronomy, creation of a highly reliable catalogue of approximately 7,200 periodically variable stars (RR Lyrae, eclipsing binaries, SX Phe stars and LPVs) as well as search for optical signatures of exotic transient events (such as tidal disruption event candidates), are presented.

The detection of stellar streams, tidal disruptions and merger remnants within the stellar halo provide observational insight into the formation and evolution history of the Galaxy. Often these stellar over-densities have in the past been detected using visual inspection. However, the expected data volume from Gaia will make detection via visual inspection unfeasible and requires an effective detection methodology. Here we present proof of concept results using a point ordering method to identify clustering (OPTICS). We find that OPTICS is an advantageous clustering algorithm to detect non-convex and irregular shaped streams and clouds while simultaneously detecting small scale-substructure in large scale over-densities.

Different star formation scenarios predict a variety of forms for young star clusters. The recent discovery of two dynamically distinct populations in the young cluster Gamma Velorum allows us to investigate the star formation mechanism.

Multiple populations are found ubiquitously in Galactic globular clusters and in the clusters in the Magellanic Clouds. However their presence in Galactic open clusters is still matter of debate. The Gaia-ESO Survey data allow us to tackle this issue on a homogeneous data set. Here we summarize the early results.

The Radial Velocity Experiment (RAVE) is a large wide-field spectroscopic stellar survey of the Milky Way. Over the period 2003-2013, 574,630 spectra for 483,330 stars have been amassed at a resolution of R=7500 in the Ca-triplet region of 8410–8795 Å. Wavelength coverage and resolution are thus comparable to that anticipated from the Gaia RVS. Derived data products of RAVE include radial velocities, stellar parameters, chemicals abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and absorption measures based on the diffuse interstellar bands (DIB) at 8620 Å. Since more than 290 000 RAVE targets are drawn from the Tycho-2 catalogue, RAVE will be an interesting prototype for the anticipated full Gaia data releases, in particular when combined with the early Gaia data releases, which contain astrometry but not yet stellar parameters and abundances.

Galactic Archaeology has recently been challenged by the fact that stars observed now in a certain location are not necessarily born there, but could have been kicked out from their birth places by different internal and/or external processes. We have made one of the first attempts to quantify how important stellar mixing could be in the case of our Galaxy, and how much of the original chemodynamical correlations would have been destroyed by such processes. Our unique approach has allowed us to conclude that although stellar mixing does take place in our Galaxy, many of the main relations between chemistry and age suggested by pure chemical evolution models are still generally valid. However, stringent constraints can be obtained only when stellar ages will be known for a large number of field stars. This is certainly one of the goals of Gaia, but in the meantime it has been shown that Asteroseismology can also provide a way to estimate ages of giants, even at large distances from the Sun. Here we present the first results obtained with a sample of CoRoT stars that have APOGEE spectra, in the framework of the CoRoGEE collaboration. The results coming from this still very recent approach (i.e. asteroseismology of Galactic populations) reveals that we might be on the right track in terms of quantifying radial mixing, but these results also suggest the chemical enrichment of the Galactic disk(s) to have been more complex than previously envisaged. Intriguingly, we find that the use of [α/Fe]-ratios as proxy for age, although generally valid, breaks down for some stars.

We study the structure of the inner Milky Way using the latest data release of the Vista Variables in the Via Lactea (VVV) survey. VVV is a deep near-infrared, multi-colour (Z,Y,J,H, Ks) photometric survey with a coverage of 320 square degrees towards the bulge region. We use the photometric properties of red clump (RC) stars to build a high resolution (1′× 1′) extinction map which we use to de-redden the photometry. From the colour-magnitude diagrams we extract the red giant branch population to investigate its 3D density distribution in the central 4–12 kpc of the MW. In the very central regions of the bulge, at |l| < 4∘ and |b| < 2.5∘, we find a high significance overdensity not described by a simple density model.

We discuss the selection of blue horizontal branch stars (BHBs) using preliminary Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) color data and outline techniques for structure detection using those data. We first outline the adaptation of an old color selection for for BHBs using Sloan Digital Sky Survey (SDSS) data to the Pan-STARRS filter set. We next outline a rudimentary search algorithm designed to autonomously detect substructure in the Galactic halo. Finally we discuss preliminary results and comment on future refinements to the process.

We describe a new method for analysing N-body simulations. The method makes a blind search for resonant orbits by making use of the fact that resonant orbits will return to some previously occupied region of phase space. An application of this method is made to the N-body simulation of Shen et al. (2010). The simulation is host to a strong and persistent central bar that drives resonances and angular momentum exchange, even in the outer parts of the disc. We deconstruct the barred disc into it's constituent resonant orbit families. We then study the contribution of each orbit family to the kinematic landscape around the disc.

The formation and evolution of the thick disc of the Milky Way remain controversial. We make use of the Besançon Galaxy model, which among other utilities can be used for data interpretation and to test different scenarios of galaxy formation and evolution. We examine these questions by studying the metallicity distribution of the thin and thick disc with the help of a sample of Main Sequence turn-off stars from the SEGUE survey. We developed a tool based on a MCMC-ABC method to determine the metallicity distribution and study the correlation between the fitted parameters. We obtained a local metallicity of the thick disc of − 0.47 ± 0.03 dex similar to previous studies and the thick disc shows no gradient. A flat gradient in the thick disc can be a consequence of radial mixing or the result of a strong turbulent gaseous disc.

The temporal evolution of the terrestrial impact cratering rate over the past 250 Myr is dominated by a trend increasing towards the present. We find that the Sun's motion through the Galaxy plays at best a minor role in modulating this cratering rate. Moreover, the solar apex motion can explain the non-uniform longitude distribution of the perihelia of long period comets without invoking a solar companion in the outer Oort cloud.

Two new analysis of SDSS and 2MASS surveys are used to constrain the characteristics of the thin and thick disc of the Milky Way, based on a population synthesis model and a MCMC scheme to constrain model parameters. These studies show that 1) the thick disc has been formed during an extended period of time and it was contracting during this phase; 2) the external thin disc is shown to have characteristics which vary with age such as the scale length, warp orientation, warp and flare slopes. The thick disc undergoing a contraction with time while the thin disc forming inside-out clearly indicate that they are truly distinct components of the Galaxy.

The stellar overdensity due to the Perseus arm has been detected in the anticenter direction through individual field stars. For that purpose, a Strömgren photometric survey covering 16∘2 was developed with the Wide Field Camera at the Isaac Newton Telescope. This photometry allowed us to compute individual physical parameters for these stars using a new method based on atmospheric models and evolutionary tracks. The analysis of the surface density as a function of distance for intermediate young stars in this survey allowed us to detect an overdensity at 1.6 ± 0.2 kpc from the Sun, that can be associated with the Perseus arm, with a surface density amplitude of ∼14%. The significance of the detection is above 4σ for all the cases. The fit for the radial scale length of the Galactic disk provided values in the range [2.9,3.5] kpc for the population of the B4-A1 stars. We also analyzed the interstellar visual absorption distribution, and its variation as a function of distance is coherent with a dust layer before the Perseus arm location.

We discuss the synergy of Gaia and the Large Synoptic Survey Telescope (LSST) in the context of Milky Way studies. LSST can be thought of as Gaia's deep complement because the two surveys will deliver trigonometric parallax, proper-motion, and photometric measurements with similar uncertainties at Gaia's faint end at r = 20, and LSST will extend these measurements to a limit about five magnitudes fainter. We also point out that users of Gaia data will have developed data analysis skills required to benefit from LSST data, and provide detailed information about how international participants can join LSST.

The GALAH survey targets one million stars in the southern hemisphere down to a limiting magnitude of V = 14 at the Anglo-Australian Telescope. The project aims to measure up to 30 elemental abundances and radial velocities (≈1 km s−1 accuracy) for each star at a resolution of R = 28,000. These elements fall into 8 independent groups (e.g.α, Fe peak, r-process). For all stars, Gaia will provide distances to 1% and transverse velocities to 1 km s−1 or better, giving us a 14D set of parameters for each star, i.e. 6D phase space and 8D abundance space. There are many scientific applications but here we focus on the prospect of chemically tagging the thick disk and making a direct measurement of how stellar migration evolves with cosmic time.

WEAVE, the next-generation spectroscopic facility for the WHT, is being built with Gaia support as a central science case. WEAVE is a π-square degree multi-fibre system capable of deploying either 1000 single-fibre probes, 20 mini-IFUs or a single large IFU, to feed a two-arm bench spectrograph. With two spectral resolution modes, main products in support of Gaia will be 1–2 km s−1 accuracy radial velocities in the range 16 < V < 20, and abundances of individual elements to ∼0.1 dex up to V ∼ 17. WEAVE will be used to carry out massive surveys that exploit Gaia data in topics of Milky Way astronomy and stellar evolution.