The Gaia Astrometric Survey

In its all-sky survey, the ESA global astrometry mission Gaia will perform high-precision astrometry and photometry for 1 billion stars down to $V = 20$ mag. The data collected in the Gaia catalogue, to be published by the end of the next decade, will likely revolutionize our understanding of many aspects of stellar and Galactic astrophysics. One of the relevant areas in which the Gaia observations will have great impact is the astrophysics of planetary systems. This summary focuses on a) the complex technical problems related to and challenges inherent in correctly modelling the signals of planetary systems present in measurements collected with a space-borne observatory poised to carry out precision astrometry at the micro-arcsecond ($\mu$as) level, and b) on the potential of Gaia $\mu$as astrometry for important contributions to the astrophysics of planetary systems.Comment: 2 pages. Summary of an invited talk given at Special Session 6 (Planetary Systems as Potential Sites for Life) of the XXVIIth IAU General Assembly held in Rio de Janeiro (Brazil). To appear in IAU Highlights of Astronomy 15 (2010

White Dwarf Planets from GAIA

We investigate the potential of high-precision astrometry with GAIA for detection of giant planetary companions to nearby white dwarfs. If one considers that, to date, no confirmed planets around single white dwarfs are known, the results from GAIA will be crucial to study the late-stage evolution of planetary systems and to verify the possibility that 2nd-generation planets are formed.Comment: Part of PlanetsbeyondMS/2010 proceedings http://arxiv.org/html/1011.6606v1, Proc. of the workshop on "Planetary Systems beyond the Main Sequence" (Bamberg, 11-14 August 2010), AIPC in press (eds. S. Schuh, H. Drechsel and U. Heber), 4 pages, 1 figur

Detectability of substellar companions around white dwarfs with Gaia

To date not a single-bona fide planet has been identified orbiting a single white dwarf. In fact we are ignorant about the final configuration of >95% of planetary systems. Theoretical models predict a gap in the final distribution of orbital periods, due to the opposite effects of stellar mass loss (planets pushed outwards) and tidal interactions (planets pushed inwards) during the RGB and the AGB stellar expansions. Over its five year primary mission, Gaia is expected to astrometrically detect the first (few tens of) WD massive planets/BDs giving first evidence that WD planets exist, at least those in wide orbits. In this article we present preliminary results of our simulations of what Gaia should be able to find in this field.Comment: Proceedings of the 19th European Workshop on White Dwarfs (Montr\'eal 11-15 August 2014). To appear on ASP Conference Series; 4 pages, 2 figure

Observational Tests of the Formation, Migration, and Evolution Processes of Gas Giant Planets

We have conducted a set of experiments aimed at improving our knowledge of the formation, migration, and evolution processes of gas giant planets, utilizing a combination of spectroscopic, photometric, and astrometric techniques.First, the distributions of planet masses and orbital elements, different correlations among them, and measurable differences in planetary frequency are likely to be generated by diverse planetary formation scenarios and evolution mechanisms as well as different characteristics of the parent star (binarity, spectral type metallicity, age). We have found new evidence for a correlation between the orbital periods of extrasolar planets and the metallicity of the host stars. We have undertaken a precision radial-velocity survey of a sample of 200 metal-poor stars, to confirm or disprove the correlation, to refine our understanding of the dependence of planetary frequency on the metallicity of the host stars, and to put constraints on proposed models of giant planet formation.Second, the internal structure and composition of the atmospheres of close-in giant planets can be better understood if measurements of their radii and actual masses are available, for a range of different planet host spectral types. We have measured the spectroscopic orbit of TrES-1, the transiting Jupiter-sized planet of a moderately bright K0V star, and by improving on the determination of the stellar parameters, we havederived accurate estimates of its radius and mass.Finally, the actual source responsible for eccentricity excitation could be understood andthe long-term dynamical evolution better characterized if coplanarity measurements of multiple-planet orbits were to be carried out. We have quantified the ability of the Space Interferometry Mission to obtain accuratemeasurements of the actual masses, orbital parameters, and relative inclination angles for systems of giant planets around stars in the solar neighborhood.We conclude describing four experiments to investigate further the transiting planet TrES-1 and its parent star. These are: 1) infrared observations of the secondary eclipse; 2) high-precision visible wavelength observations of the primary eclipse; 3) a detailed chemical abundance analysis of the host star; 4) a direct distance measurement for the system

Gaia and exoplanets: a revolution in the making

The Gaia global astrometry mission is now entering its fourth year of routine science operations. With the publication of the first data release in September 2016, it has begun to fulfil its promise for revolutionary science in countless aspects of Galactic astronomy and astrophysics. I briefly review the Gaia mission status of operations and the scenario for the upcoming intermediate data releases, focusing on important lessons learned. Then, I illustrate the Gaia exoplanet science case, and discuss how the field will be revolutionized by the power of microarcsecond (μas) astrometry that is about to be unleashed. I conclude by touching upon some of the synergy elements that will call for combination of Gaia data with other indirect and direct detection and characterization techniques, for much improved understanding of exoplanetary systems

Exoplanetology with Gaia

I will briefly review the Gaia mission status of operations and the scenario for the upcoming intermediate data releases, focusing on important lessons learned. I will then illustrate the Gaia exoplanet science case, and discuss how the field will be revolutionized by the power of micro-arcsecond (μas) astrometry that is about to be unleashed

Gaia: Status and Promises

The power of micro-arcsecond (µas) astrometry is about to be unleashed. ESA's Gaia mission, now entering its second year of routine science operations, will soon fulfil its promise for revolutionary science in the countless aspects of Galactic astronomy and astrophysics. I will briefly review the Gaia mission status of operations, and the scenario for intermediate data releases. Iwill then illustrate the potential of µas astrometry for detection and improved characterization of planetary systems in the neighborhood of the Sun. <P /

The contribution of the major planet search surveys to EChO target selection

The EChO core science will be based on a three tier survey, each with increasing sensitivity, in order to study the population of exo-planets from super-Earths to Jupiter-like planets, in the very hot to temperate zones (temperatures of 300 K - 3000 K) of F to M-type host stars. To achieve a meaningful outcome an accurate selection of the target sample is needed. In this paper we analyse the targets, suitable for EChO observations, expected to result from a sample of present and forthcoming detection surveys. Exoplanets currently known are already sufficient to provide a large and diverse sample. However we expect the results from these surveys to increase the sample of smaller planets that will allow us to optimize the EChO sample selection.Comment: Submitted to Experimental Astronom