1. UCL, 7-8 April 2010 EPRAT Workshop The Gaia Astrometric Survey A. Sozzetti A. Sozzetti INAF – Osservatorio Astronomico di Torino

2. UCL, 7-8 April 2010 EPRAT Workshop 10 μas Astrometry: 2012-2017

3. UCL, 7-8 April 2010 EPRAT Workshop Now August 2012 Gaia Project Status and Schedule

4. UCL, 7-8 April 2010 EPRAT Workshop Performance on red stars is 20%-30% better at bright mags

5. UCL, 7-8 April 2010 EPRAT Workshop Sozzetti 2009 Gaia Discovery Space 1)2-3 M J planets at 2<a<4 AU are detectable 2<a<4 AU are detectable out to~200 pc around out to~200 pc around solar analogs solar analogs 2) Saturn-mass planets with 1<a<4 AU are measurable 1<a<4 AU are measurable around nearby (<25 pc) around nearby (<25 pc) M dwarfs M dwarfs Critical assumption: σ A ~ 15 μas (6<V<13)

6. UCL, 7-8 April 2010 EPRAT Workshop How Many Planets will Gaia find? How Many Multiple-Planet Systems will Gaia find? Star counts (V<13), F p (M p,P), Gaia completeness limit Star counts (V<13), F p,mult, Gaia detection limit Casertano, Lattanzi, Sozzetti et al. 2008 Unbiased, magnitude-limited census of hundreds of thousands stars

7. UCL, 7-8 April 2010 EPRAT Workshop How do Planet Properties and Frequencies Depend Upon the Characteristics of the Parent Stars (also, What is the Preferred Mechanism of Gas Giant Planet Formation?)? Gaia will test the fine structure of giant planet parameters distributions and frequencies, and investigate their possible changes as a function of stellar mass, metallicity, and age with unprecedented resolution 10 4 stars per 0.1 M Sun bin! Johnson 2007 Casertano et al. 2008 ? Sozzetti et al. 2009 The Gaia Legacy (1)

8. UCL, 7-8 April 2010 EPRAT Workshop The Gaia Legacy (2) How Do Dynamical Interactions Affect the Architecture of Planetary Systems? E.g., coplanarity tests will allow to determine the relative importance of many proposed mechanisms for eccentricity excitation in a statistical sense, not just on a star-by-star basis. Thommes & Lissauer 2003 a)Interactions between a planet and the gaseous/planetesimal disk? gaseous/planetesimal disk? b)Planet-planet resonant interactions? c)Close encounters between planets? d) Secular interactions with a companion star? Very strong impact on habitability studies too!

9. UCL, 7-8 April 2010 EPRAT Workshop What Are the Phase Functions and Light Curves of Gas Giant Planets? Gaia could provide important supplementary data to aid in the interpretation of direct detections of giant exoplanets both by helping to characterize their thermo-physical conditions and by determining the epoch and location of their maximum brightness. The Gaia Legacy (3) Burrows et al. 2005

10. UCL, 7-8 April 2010 EPRAT Workshop The Gaia Legacy (4) Where Are the Earth-Like Planets, and What Are Their Characteristics? Gaia will provide important supplementary data for the optimization of the characterization of targets, e.g., by screening all stars within ~25 pc for Jupiter- and Saturn-sized planets out to several AUs. Neptune-mass (and smaller) planets will be detectable around thousands of M dwarfs Kaltenegger et al. 2007 Nearby stars: THE targets. They must be studied as best as one can

11. UCL, 7-8 April 2010 EPRAT Workshop Conclusions Gaia will derive the largest compilation of astrometric orbits of giant planets (in many cases signposts of more interesting systems!), unbiased across all spectral types and ages up to D~200 pcGaia will derive the largest compilation of astrometric orbits of giant planets (in many cases signposts of more interesting systems!), unbiased across all spectral types and ages up to D~200 pc Get ready: Gaia data will start rolling in as early as ~2015Get ready: Gaia data will start rolling in as early as ~2015 Gaia can crucially contribute to several aspects of planetary systems astrophysics (formation theories, dynamical evolution), in combination with present-day and future extrasolar planet search programsGaia can crucially contribute to several aspects of planetary systems astrophysics (formation theories, dynamical evolution), in combination with present-day and future extrasolar planet search programs The Gaia community has already started coordinated efforts (GREAT) for the full exploitation of the science (including exoplanets)The Gaia community has already started coordinated efforts (GREAT) for the full exploitation of the science (including exoplanets) See Gaia in context as well as a synergy: it will improve your roadmapping exercise!See Gaia in context as well as a synergy: it will improve your roadmapping exercise!