Intrinsic stellar variability can hinder the detection of shallow transits, particularly in space-based data. Therefore, this variability has to be filtered out before running the transit search. Unfortunately, filtering out the low frequency signal of the stellar variability also modifies the transit shape. This results in errors in the measured transit depth and duration used to derive the planet radius, and orbital inclination. We present an evaluation of the magnitude of this effect based on 20 simulated light curves from the CoRoT blind exercise 2 (BT2). We then present an iterative filter which uses the strictly periodic nature of the transits to separate them from other forms of variability, so as to recover the original transit shape before deriving the planet parameters. On average with this filter, we improve the estimation of the transit depth and duration by 15% and 10% respectively.

The ESO Very Large Telescope Interferometer (VLTI) is arguably the most powerful optical interferometric facility available at present. In addition to the wide choice of baselines and the light collecting power of its 8.2 m and 1.8 m telescopes, the VLTI also offers a smooth and user-friendly operation which makes interferometry accessible to any astronomer and covers a wide range of scientific applications. Behind the routine scientific operations, however, the VLTI is in constant evolution. I will present some of the technological and instrumental improvements which are planned for the near and mid-term future, and discuss their implications for astrometry in particular. Among them, the PRIMA facility and the proposed GRAVITY instrument are designed to reach the level of 10 microarcseconds in the near-infrared.

We describe a way to compare current relativistic astrometric models accurate to the micro-arcsecond level. The observed stellar direction can be written as a function of several parts, linking the astrometric observables to the relativistic effects associated to the stellar kinematical properties and distances as seen inside the gravitational field of our Solar System, i.e. the so called relativistic astrometric parameters, providing a tool for comparing the RAMOD framework to the pM/pN approaches.

Gravitomagnetic effects are studied in this paper. Starting from the metric in the BCRS and then using the matching method, the metric in the GCRS are derived. Furthermore, we give some estimation of the order of the gravitomagnetic effects on the lunar orbit.

We have investigated accretion of terrestrial planets from planetesimals around M dwarfs through N-body simulations including the effect of tidal interaction with disk gas. Because of low luminosity of M dwarfs, habitable zones around them are located near the disk inner edge. Planetary embryos undergo type-I migration and pile up near the disk inner edge. We found that after repeated close scatterings and occasional collisions, three or four planets eventually remain in stable orbits in their mean motion resonances. Furthermore, large amount of water-rich planetesimals rapidly migrate to the terrestrial planet regions from outside of the snow line, so that formed planets in these regions have much more water contents than those around solar-type stars.

We report the results of a survey of late-type giants aimed at understanding the nature of the disk and nearby halo Galactic stellar populations. We have obtained medium resolution (2–4 Å) spectra for 749 late K and early M giants at mid-latitudes selected from the 2MASS catalog with the FOBOS system at Fan Mountain Observatory. These spectra provide radial velocities (RVs) at the 5 km s−1 level, spectroscopic [Fe/H] good to σ[Fe/H] = 0.25 dex, and information on the relative abundances of Mg/Fe and Na/Fe in these stars. Proper motions from UCAC2 are used to search for local substructures, in particular the leading arm of the Sagittarius tidal streamer passing through the solar neighborhood. The combined proper motions and RVs yield full 6D stellar space motions. We have, by way of kinematics, relatively cleanly isolated the thick disk from the typically high velocity substructures that compose the nearby halo.

We find evidence for substructure in the kinematics and metallicities of local halo stars.

Space science missions, and astronomy missions in particular, capture the public imagination at all levels. ESA's Gaia mission is no exception to this. In addition to its key scientific goal of providing new insight into the origin, formation, and evolution of the Milky Way, Gaia also touches on many other scientific topics of broad appeal, for example, solar system objects, stars (including rare and exotic ones), dark matter, gravitational light bending. The mission naturally provides a rich resource for outreach possibilities whether it be to the general public, or to specific interest groups, such as scientists from other fields or educators. We present some examples of possible outreach activities for Gaia.

We are developing a new near-infrared high-resolution (R[max] = 100,000) and high-sensitive spectrograph WINERED, which is specifically customized for short NIR bands at 0.9–1.35 μm. WINERED employs an innovative optical system; a portable design and a warm optics without any cold stops. The planned astrometric space mission JASMINE will provide precise positions, distances, and proper motions of the bulge stars. The missing components, the radial velocity and chemical composition will be measured by WINERED. These combined data brought by JASMINE and WINERED will certainly reveal the nature of the Galactic bulge. We plan to complete this instrument for observations of single objects by the end of 2008 and to attach it to various 4–10m telescopes as a PI-type instrument. We hope to upgrade WINERED with a multi-object feed in the future for efficient survey of the JASMINE bulge stars.

We investigate the dynamical response of a non-synchronized hot Jupiter to stellar irradiation. In our current model, the stellar radiation acts like a diurnal thermal forcing from the top of a radiative layer of a hot Jupiter. If the thermal forcing period is longer than the sound speed crossing time of the planet's surface, the forcing can excite internal waves propagating into the planet's interior. When the planet spins faster than its orbital motion, these waves carry negative angular momentum and are damped by radiative loss as they propagate downwards from the upper layer of the radiative zone. As a result, the upper layer gains the angular momentum from the lower layer of the radiative zone. Simple estimates of angular momentum flux are made for all transiting planets.

Utilization of sub-milliarcsecond trigonometric parallaxes shifts the classical problem of calibration of stellar parameters to a new level of complexity. Derivation of stellar luminosity from the parallaxes is not a straightforward task with a number of statistical effects, such as Malmquist bias, to be taken into account. Different methods are to be used in order to derive parameters of luminosity function depending on the nature of underlying stellar sample. It is emphasized that any combination of astrometric parameters (i.e. parallaxes) and astrophysical ones must be handled carefully to avoid or reduce statistical effects, which otherwise may seriously affect the astrophysical applications.

Tidal vertical variations have been removed in astrometric observations, but the non-tidal ones remain unknown. From the repeated observations of gravimetric networks in China, the non-tidal vertical variations at Beijing-Tangshan and West Yunnan are determined, which are of the order of 0.″2. Astrometric results, including past star catalogs, based on these observations should be corrected.

The accuracy of planetary satellites ephemerides is determined not only by the accuracy of dynamical model (internal accuracy) but also by the accuracy of the observations (external accuracy) used to fit the initial parameters of a model. This external accuracy extrapolated in the future is unknown most of the time and tends to degrade the global accuracy of ephemerides. Even if we can estimate the quality of the ephemerides by comparison with observations, we do not know how to determinate the evolution of the accuracy outside the period of observations. We will present a statistical method, resampling of observations, which allows a better estimation of the extrapolated accuracy in the future.

Extrasolar planet surveys have discovered over two dozen multiple planet systems. As radial velocity searches push towards higher precisions and longer survey durations, they can be expected to discover an even higher fraction of multiple planet systems. Combined with radial velocity data, dynamical studies of these systems can constrain planet masses and inclinations, measure the significance of resonant and secular interactions, and provide insights into the formation and evolution of these systems. Here, we review the dynamical properties of known extrasolar multiple planet systems and their implications for planet formation theory. We conclude by outlining pressing questions to be addressed by a combination of future observations and theoretical research.

This paper emphasizes the connection between solar and extra-solar debris disks: how models and observations of the Solar System are helping us understand the debris disk phenomenon, and vice versa, how debris disks are helping us place our Solar System into context.

Major advances in our understanding of the Universe have historically come from dramatic improvements in our ability to accurately measure astronomical quantities. The astrometric observations obtained by modern digital sky surveys are enabling unprecedentedly massive and robust studies of the kinematics of the Milky Way. For example, the astrometric data from the Sloan Digital Sky Survey (SDSS), together with half a century old astrometry from the Palomar Observatory Sky Survey (POSS), have enabled the construction of a catalog that includes absolute proper motions as accurate as 3 mas/year for about 20 million stars brighter than V=20, and for 80,000 spectroscopically confirmed quasars which provide exquisite error assessment. We discuss here several ongoing studies of Milky Way kinematics based on this catalog. The upcoming next-generation surveys will maintain this revolutionary progress. For example, we show using realistic simulations that the Large Synoptic Survey Telescope (LSST) will measure proper motions accurate to 1 mas/year to a limit 4 magnitude fainter than possible with SDSS and POSS catalogs, or with the Gaia survey. LSST will also obtain geometric parallaxes with accuracy similar to Gaia's at its faint end (0.3 mas at V=20), and extend them to V=24 with an accuracy of 3 mas. We discuss the impact that these LSST measurements will have on studies of the Milky Way kinematics, and potential synergies with the Gaia survey.

In this article we examine the motion of fictitious Trojan planets close to the equilateral Lagrangean equilibrium points in extrasolar planetary systems. Whether there exist stable motion in this area or not depends on the massratio of the primariy bodies in the restricted three body problem, namely the host star and the gasgiant. Taking into account also the eccentricity of the primaries we show via results of extensive numerical integrations that Trojan planets may survive only for e < 0.25. We also show first results of a mapping in the 1:1 resonance with a gas giant on an eccentric orbit which is applied to the extrasolar planetary systems HD 17051. We furthermore study the influence of an additional outer planet which perturbs the motion of the gasgiant as well as the Trojan cloud around its L4 Lagrangean point.

Gaia is an ESA cornerstone mission which will observe some billion stars in the galaxy enabling micro-arcsec astrometric catalogues to be constructed. In addition Gaia will produce high quality photometric and spectroscopic catalogues.

The data processing tasks are large and complex. A European consortium has been formed - the Gaia Data Processing and Analysis Consortium (DPAC). This paper describes the form of the UK Gaia Data Flow System Project contribution to the DPAC.

We investigate type I migration in a two-dimensional adiabatic disk. We find entropy perturbations that are advected in the planet's coorbital region. These entropy perturbations yield an excess of corotation torque that scales with the unperturbed entropy gradient at corotation. This torque excess can be large enough to slow down migration significantly, or even stop it.

We present an observation method to obtain a relative astrometric precision of about 100 . . . 150 μas with ground-based and single-aperture observations. By measuring the separation of double or triple stars we want to determine the astrometric signal of an unseen substellar companion as a periodic change in the separation between the stellar components. Using an adaptive optics system we correct for atmospheric turbulences and furthermore by using a narrow band filter in the near infrared we can suppress differential chromatic refraction effects. To reach a high precision we use a statistical approach. Using the new observation mode “cube-mode” (where the frames were directly saved in cubes with nearly no loss of time during the readout), we obtain several thousand frames within half an hour. After the verification of the Gaussian distributed behaviour of our measurements (done with a Kolmogorov-Smirnov-Test) the measurement precision can be calculated as the standard deviation of our measurements divided by the square root of the number of frames.

To monitor the stability of the pixel scale between our observations, we use the old globular cluster 47 Tuc as a calibration system.

Near-separatrix motion is a kind of motion of two planets with their relative apsidal longitude near the boundary between libration and circulation. Observed multiple planetary systems seem to favor near-separatrix motions between neighboring planets. In this report, we study the probability that near-separatrix motion occurs with both the linear secular system and full three-body systems. We find that generally the ratio of near-separatrix motion is small unless the eccentricities of the two planets differ from each other by an order of magintude, or they are in mean motion resonance. To explore the dynamical procedures causing the near-separatrix motion, we suppose a modification to scattering model by adding a mass-accretion process during the protoplanet growth. Statistics on the modified scattering model indicate that the probability of the final planet pairs in near-separatrix motion is high (∼ 85%), which may explain the high occurrence of near-separatrix motions in observed planetary systems.