The existing outreach resources available to the scientific community that have been updated (like the information sheets or the little books of Gaia) are shown. New features (vodcast in several languages, new posters and a science performance web page) and short term projects (new and centralised image gallery) are also presented.

ELSA stands for the ambitious goal of “European Leadership in Space Astrometry”. In this closing contribution I will examine how the ELSA network has advanced this goal. I also look ahead to the time when the Gaia data will be published and consider what needs to be done to maintain European leadership.

Gaia will provide accurate parallaxes, spectrophotometry and spectroscopy for hundreds of thousands of emission-line stars across the whole HR diagram. In preparation for the Gaia mission, we are developing algorithms to recognize and classify emission-line stars. A large collection of ground-based spectroscopic observations has been collected and will be used for testing and training the algorithms.

Gaia will also provide information on several millions of early-type stars. Determining accurate parameters for these stars from Gaia data only will be difficult due to the AV – Teff degeneracy.

Since January 1st, 2010, the IAU (International Astronomical Union) fundamental celestial reference frame has been the 2nd International Celestial Reference Frame (ICRF2), which is composed of Very Long Baseline Interferometry (VLBI) positions for more than 3000 extragalactic radio sources. This frame is constantly improving through joint efforts of the VLBI community. By surveying the whole sky up to magnitude 20, the European space astrometric mission Gaia will soon create its own celestial reference frame directly in the optical domain and with many more sources. By 2015–2020, the two frames will thus cohabit and it will be important to align these to the highest accuracy for consistency between optical and radio positions. In this paper, we present the various observational approaches that are undertaken to improve the VLBI frame in the future. These include extension to weaker sources for densification, extension to higher radio frequencies to take advantage of the more compact morphology of the sources at these frequencies, and further observations in the southern hemisphere for homogeneous sky coverage. We also elaborate on how such future radio frames should contribute to highly-precise alignment between the VLBI and Gaia frames within the next decade.

This is an overview of the processing of the dispersed images for the Blue and Red Photometers in the Gaia Satellite. The data are corrected for CCD related effects in the pre-processing, where also the sky background and the flux by neighbours are removed; the data are then internally calibrated to the same “mean instrument” and externally calibrated to obtain spectrum and flux in physical units, which will be stored in the final catalogue.

We have developed a method for obtaining membership of globular cluster NGC 6121 by radius-velocity profiles of a self- gravitating system. Previous works usually identified the membership of clusters by spatial distribution (radius), velocity distribution (proper motion), and photometry (isochrone in colour-magnitude diagram). However, field star contamination might be severe by method of spatial distribution and photometric method, and many high speed stars near the central region might be missed by velocity distribution method. More complete members could be identified by this method.

By means of N-body simulations, we have investigated the impact of minor mergers on the angular momentum content and kinematical properties of a disc galaxy. Our simulations cover a range of initial orbital characteristics and the system consists of a massive galaxy with a bulge and a stellar disc merging with a much less massive gasless companion. Our results show that: (1) during the process of merging, the disc of the primary galaxy becomes kinematically hotter and thicker; (2) its specific angular momentum always decreases, independent of the orbit or morphology of the satellite galaxy; (3) the decrease in the rotation velocity of the primary galaxy is accompanied by a change in the anisotropy of the stellar orbits, which becomes increasingly radially dominated as the merger advances; (4) the radial velocity dispersion increases at all radii, but in particular in the outermost regions; (5) at the same time, the transverse velocity decreases throughout the whole disc, except in the inner region, where the constribution of bulge stars leads to an increase of σt.

We are planning three space astrometry missions as a series of JASMINE missions; Nano-JASMINE, Small-JASMINE and (Medium-sized)JASMINE. JASMINE is an abbreviation of Japan Astrometry Satellite Mission of INfrared Exploration. The JASMINE mission will measure in an infrared band annual parallaxes, positions on the celestial sphere, and proper motions of many stars in the bulge of the Milky Way (the Galaxy) with high accuracies. A target launch date is the first half of the 2020s. Before the launch of JASMINE, we are planning Nano-JASMINE and Small-JASMINE. Nano-JASMINE uses a very small nano-satellite and it is determined to be launched in 2011. Small-JASMINE is a downsized version of the JASMINE satellite, which observes toward restricted small regions of the Galactic bulge. A target launch date is around 2016. A completely new “map” of the Galactic bulge given by Small-JASMINE and JASMINE will bring us many exciting scientific results.

We report the results of performance evaluation of the first Japanese astrometry satellite, Nano-JASMINE. It is a very small satellite and weighs only 35 kg. It aims to carry out astrometry measurement of nearby bright stars (z ≤ 7.5 mag) with an accuracy of 3 milli-arcseconds. Nano-JASMINE will be launched by Cyclone-4 rocket in August 2011 from Brazil. The current status is in the process of evaluating the performances. A series of performance tests and numerical analysis were conducted. As a result, the engineering model (EM) of the telescope was measured to be achieving a diffraction-limited performance and confirmed that it has enough performance for scientific astrometry.

We simulated the data outputs of the first Japanese astrometry satellite Nano-JASMINE, which is scheduled to be launched by the Cyclone-4 rocket in August 2011. The simulations were carried out using existing stellar catalogues such as the Hipparcos catalogue, the Tycho catalogue, and the Guide Star catalogue version 2.3. Several statics are shown such as the number of stars those will be measured distances using annual aberration observations. The method for determining the initial direction of the satellite’s spin axis has also been discussed. In this case, the frequency of bright stars observed by the satellite is an important factor.

A spectroscopic survey of nearly 700 stars probing the Galactic Thick Disc far from the Solar neighbourhood is performed. The MATISSE (MATrix Inversion for Spectral SynthEsis) algorithm is developed and trained in order to automatically obtain atmospheric parameters of stars. The derived effective temperatures, surface gravities and overall metallicities are then combined to stellar evolution isochrones, radial velocities and proper motions to derive the distances, kinematics and orbital parameters of the sample stars. Results are compared with simulations from the Besançon model of the Milky Way.

Detection of a composite flux in Gaia photometry can serve as an indication of a photometrically unresolved binarity and can allow us to contribute to the parameterization of the components of binary systems. A main goal of the present study is to develop a method of automatic photometric detection, based on theoretical stellar spectral energy distributions and general understanding of binary evolution.

The following procedure is applied to achieve the declared goal. One can compose possible pairs of components, based on evolution concept, and using theoretical binary evolutionary tracks. This can be done for all stages of binary evolution, excluding perhaps the most marginal and rapid stages. Theoretical spectrophotometric spectral energy distributions and response functions of Gaia photometric bands allows us to compute colour-indices of such pairs, when they are unresolved, as well as of single stars. Usage of an interstellar extinction law gives us theoretical colour-indices of reddened objects, both single stars and unresolved binaries. When plotted on a multidimensional Gaia colour space, they allow us to indicate areas, where unresolved binaries can be easily separated from single stars. The procedure also indicates Gaia colour indices, suitable to distinguish those pairs from single stars.

As an output of the procedure, a Gaia list of detected photometrically unresolved binaries with physical parameters can be compiled.

We present a gridified stellar energy flux modelling software SYNTSPEC for stellar spectra analysis. It is an example of data- and compute-intensive application running on the testbed of the Enabling Grids for E-sciencE (EGEE) Grid compatible infrastructure, which brings the new quality to the research in astrophysics. The multi job application is running within the GRIDCOM system – a user friendly interface that allows a virtual work of a physically spread scientific group. The SYNTSPEC software calculates stellar energy fluxes and normalized to the continuum spectra that are applied for stellar classification and determination of chemical compositions, effective temperatures, surface gravities and other parameters of stars. The SYNTSPEC application benefits from usage of large computing resources, which makes possible calculations of synthetic stellar spectra for significant wavelength ranges and numbers of stellar parameter combinations. The specific energy flux modelling will be used for the analysis of data, which will be produced by the European Space Agency‘s Gaia space observatory.

The impact of bright extended sources on the observation and detection of faint sources by Gaia has been studied. The effect has been characterized using the representative case of stars near the Jupiter disk and consists of three parts. First, an analytical representation of the PSF, including aberrations and electronic distortions, has been developed to produce images of Jupiter and solar type stars. Second, those images have been combined to produce fields of view including Jupiter and stellar patterns. Third, the CCD images have been fed to the VPU algorithms prototype to determine the limits until which detections are possible. This work can be useful for science cases such as GAREQ.

In this study we use numerical N-body/SPH simulations to investigate the vertical stellar distribution of thick disks formed in minor mergers. These disks have a sech-shape vertical surface density profile which needs two sech functions with different scale heights to fit due to an additional stellar excesses at large heights (z ≳ 4 − 5 kpc). The scale heights of merger-induced thick disks increase with radius but the details of this thickening are sensitive to orbital configurations and gas fraction of the galaxies. The scale height of the stellar excess is constant with radius and largely independent of the initial conditions. The effects of minor mergers is cumulative in the sense that several minor mergers have the same impact of a single minor merger of the same total mass. Scattering by self-gravitating masses (clumps) in unstable gaseous disks can produce thick disks with constant scale height, however, there is not a stellar excess at large scale heights. Most of these results are found to be in good agreement with observations and thus we conclude that minor mergers remains a viable mechanism for the creation of galactic thick disks.

By fitting the revised Hipparcos intermediate astrometric data (HIAD), we obtain the photocentric orbital solutions of some single-lined spectroscopic binaries (SB1s) in the 9th Catalogue of Orbits of Spectroscopic Binaries (SB9). For SB1s with relatively small magnitude difference between the two components, we find that the primary orbit is not a good approximation of the photocentric orbit in their orbit determination and suggest that future spectroscopic observations and advanced spectral separation techniques should be applied to these systems. In order to facilitate these future observations, we also estimate the full orbital solutions and provide the observational ephemerides. As an example, we give the result for HIP 113860.

Using relative astrometry and ground based imaging, we study nearby stellar multiple systems in order to detect the astrometric signal of exoplanets around one of the stellar components. We suppress differential chromatic refraction effects by observing in the near infrared with a narrow-band filter and by choosing an iterative calibration strategy (using a stellar cluster) we obtain a precision down to 100 μas in our relative astrometric measurements. This allows us to study the occurence and properties of exoplanets in nearby (less than 100 pc) stellar multiple systems.

While trying to detect the astrometric signal of the exoplanet orbiting HD19994 A (Mayor et al. 2004), we detected the astrometric signal of a further object around the B component. This astrometric detection is confirmed by speckle interferometry and follow-up radial velocity (RV) observations. Thus, HD19994 is an exoplanet host-triple system.

Gaia will only achieve its unprecedented measurement accuracy requirements with detailed calibration and correction for radiation damage. We present our Silvaco 3D engineering software model of the Gaia CCD pixel and two of its applications for Gaia: (1) physically interpreting supplementary buried channel (SBC) capacity measurements (pocket-pumping and first pixel response) in terms of e2v manufacturing doping alignment tolerances; and (2) deriving electron densities within a charge packet as a function of the number of constituent electrons and 3D position within the charge packet as input to microscopic models being developed to simulate radiation damage.

Thick disks have been observed in many disk galaxies and our Galaxy, the Milky Way, also presents a thick disk whose main spatial, kinematic, and chemical features of this population are well established. However, the origin of this ancient component is still unclear in spite the many studies carried out and several formation scenarios proposed until now. For the first time to our knowledge, we found evidence of a kinematics-metallicity correlation, of about 40–50 km s-1 per dex, amongst thick disk stars at 1 kpc  < |z| < 3 kpc and with abundance −1 <[Fe/H]< −0.5. This finding sets important constraints on the origin of the thick disk in the context of CDM hierarchical galaxy formation mechanisms and of secular evolutionary processes in galactic disks. This result is reported and, preliminary results, based on new N-body high numerical resolution simulations of stellar disks endowed with a bulge inside a dark matter NFW halo, are presented.

Companions exert adverse effects on the relationships valid for Cepheids. Physical companions may also cause observable effects (e.g., phase jump in the pulsation, slight excitation of non-radial modes). Many new binaries among Cepheids can be revealed by using radial velocity measurements to be made by Gaia and by deriving astrometric orbit from data to be obtained over the five years of the Gaia mission.

Cluster membership of Cepheids also facilitates the calibration of the period-luminosity relationship independently of the pulsation. A brief summary on the membership of Cepheids in clusters is also given.