Most short period transiting exoplanets have circular orbits, as expected from an estimation of the circularisation timescale using classical tidal theory. Interestingly, a small number of short period transiting exoplanets seem to have orbits with a small eccentricity. Such systems are valuable as they may indicate that some key physics is missing from formation and evolution models. We have analysed the results of a campaign of radial velocity measurements of known transiting planets with the SOPHIE and HARPS spectrographs using Bayesian methods and obtained new constraints on the orbital elements of 12 known transiting exoplanets. We also reanalysed the radial velocity data for another 42 transiting systems and show that some of the eccentric orbits reported in the Literature are compatible with a circular orbit. As a result, we show that the systems with circular and eccentric orbits are clearly separated on a plot of the planetary mass versus orbital period. We also show that planets following the trend where heavier hot Jupiters have shorter orbital periods (the “mass-period relation” of hot Jupiters), also tend to have circular orbits, with no confirmed exception to this rule so far.

Thanks to the combination of transit photometry and radial velocity doppler measurements, we are now able to constrain theoretical models of the structure and evolution of objects in the whole mass range between icy giants and stars, including the giant planet/brown dwarf overlapping mass regime (Leconte et al. 2009). In the giant planet mass range, the significant fraction of planets showing a larger radius than predicted by the models suggests that a missing physical mechanism which is either injecting energy in the deep convective zone or reducing the net outward thermal flux is taking place in these objects. Several possibilities have been suggested for such a mechanism:

• • downward transport of kinetic energy originating from strong winds generated at the planet's surface (Showman & Guillot 2002),

• • enhanced opacity sources in hot-Jupiter atmospheres (Burrows et al. 2007),

• • ohmic dissipation in the ionized atmosphere (Batygin & Stevenson 2010),

• • (inefficient) layered or oscillatory convection in the planet's interior (Chabrier & Baraffe 2007),

• • Tidal heating due to circularization of the orbit, as originally suggested by Bodenheimer, Lin & Mardling (2001).

Transits give us the mass, radius, and orbital properties of the planet, all of which inform dynamical theories. Two properties of the hot Jupiters suggest they had a dramatic origin via tidal damping from high eccentricity. First, the tidally circularized planets (in the 1-4 day pile-up) lie along a relation or boundary in the mass-period plane. This observation may implicate a tidal damping process regulated by planetary radius inflation and Roche lobe overflow, early in the planets' lives. Second, the host stars of many planets have spins misaligned from the planets' orbits. This observation was not expected a priori from the conventional disk migration theory, and it was a boon for the alternative theories of planet-planet scattering and Kozai cycles, accompanied by tidal friction, which predicted it. Now we are faced with a curious observation that the misalignment angle depends on the stellar temperature. It may mean that the tide raised on the stars realigns them, the final result being the tidal consumption of hot Jupiters.

We will present our campaign to estimate the projected spin-orbit angle for transiting hot Jupiters, obtained via observations of the Rossiter-McLaughlin effect. Combining our results to those of other teams we show what the current distribution in projected spin-orbit angle is, quickly reminding what interpretation we make of it. Finally we will show early results from a campaign that we initiated, surveying the Rossiter-McLaughlin effect on transiting SB1 intended to provide a comparison sample to the transiting planet's results.

Many hot Jupiters are observed to be misaligned with respect to the rotation axis of the star (as measured through the Rossiter–McLaughlin effect) and some (about ~ 25%) even appear to be in retrograde orbits. We show that the presence of an additional, moderately inclined and eccentric massive planet in the system can naturally explain close, inclined, eccentric, and even retrograde orbits. We have derived a complete and accurate treatment of the secular dynamics including both the key octupole-order effects and tidal friction. The flow of angular momentum from the inner orbit to the orbit of the perturber can lead to both high eccentricities and inclinations, and even flip the inner orbit. In our treatment the component of the inner orbit's angular momentum perpendicular to the stellar equatorial plane can change sign; a brief excursion to very high eccentricity during the chaotic evolution of the inner orbit can then lead to rapid “tidal capture,” forming a retrograde hot Jupiter. Previous treatments of the secular dynamics focusing on stellar-mass perturbers would not allow for such an outcome, since in that limit the component of the inner orbit's angular momentum perpendicular to the stellar equatorial plane is strictly conserved. Thus, the inclination of the planet's orbit could not change from prograde to retrograde.

We investigate the tidal interactions between hot Jupiter extra-solar planets and their host stars in an effort to characterise the effects of such interactions on stellar rotation. We study the WASP-18 and WASP-19 systems, showing that in both cases tidal interactions cause the eventual spiral in of the the planet towards the Roche limit. We find that for both systems this process will cause significant spin up of the host star, independent of the precise value for the tidal quality factors. By fitting tidal evolution models to observed parameters, we are able to determine that WASP-19 b is currently spiralling in, and that it has a very short remaining lifetime ~ 3 Myr.

Planet-disk interaction predicts a change in the orbital elements of an embedded planet. Through linear and fully hydrodynamical studies it has been found that migration is typically directed inwards. Hence, this migration process gives natural explanation for the presence of the ’hot’ planets orbiting close to the parent star, and it plays a mayor role in explaining the formation of resonant planetary systems.

However, standard migration models for locally isothermal disks indicate a too rapid inward migration for small mass planets, and a large number of massive planets are found very far away from the star. Recent studies, including more complete disk physics, have opened up new paths to slow down or even reverse migration. The new findings on migration are discussed and connected to the observational properties of planetary systems.

The direct detection of an extrasolar planet can provide accurate measurements of its orbit, mass and composition, greatly improving our understanding of how planets form and evolve. Recent advances in ground-based and space-based imaging techniques have now produced the first direct images of extrasolar planets. Typically these are many-Jupiter-mass planets on wide orbits. Direct imaging therefore probes the outer architecture of planetary systems and it is highly complementary to other techniques sensitive to inner architectures. This brief review summarizes the properties of the currently imaged exoplanets, provides an update on the orbit of Fomalhaut b, and highlights the emerging phenomenon of circumplanetary disks.

Hot-Jupiters are a common sub-class of exoplanets, which are enough close to the star to undergo tidal dissipation. The continuous action of tides modify the rotation of the planets until an equilibrium situation is reached. It is often assumed that synchronous motion is the most probable outcome of tidal evolution, since synchronous rotation is observed for the majority of the satellites in the Solar System. This is true for circular orbits, but when the orbits are eccentric, tidal effects are stronger when the planets are closer to the star, and therefore, the rotation rate tends to equalize the orbital speed rate at the pericenter (which is faster than synchronous rotation). An additional complication arises if the eccentricity is not constant and undergoes periodic perturbations from an external companion. Here we obtain an expression for the equilibrium rotation of Hot-Jupiters undergoing tidal dissipation and planetary perturbations. We show that for these planets, the equilibrium rotation rate is faster than for non-perturbed eccentric orbits.

Recent observations have shown that in many exoplanetary systems the spin axis of the parent star is misaligned with the planet's orbital axis. These have been used to argue against the scenario that short-period planets migrated to their present-day locations due to tidal interactions with their natal discs. However, this interpretation is based on the assumption that the spins of young stars are parallel to the rotation axes of protostellar discs around them. We show that the interaction between a magnetic star and its circumstellar disc can (although not always) have the effect of pushing the stellar spin axis away from the disc angular momentum axis toward the perpendicular state and even the retrograde state. Planets formed in the disc may therefore have their orbital axes misaligned with the stellar spin axis, even before any additional planet-planet scatterings or Kozai interactions take place. In general, magnetosphere–disc interactions lead to a broad distribution of the spin–orbit angles, with some systems aligned and other systems misaligned.

Mean motion resonances are a common feature of both our own Solar System and of extrasolar planetary systems. Bodies can be trapped in resonance when their orbital semi-major axes change, for instance when they migrate through a protoplanetary disc. We use a Hamiltonian model to thoroughly investigate the capture behaviour for first and second order resonances. Using this method, all resonances of the same order can be described by one equation, with applications to specific resonances by appropriate scaling. We focus on the limit where one body is a massless test particle and the other a massive planet. We quantify how the the probability of capture into a resonance depends on the relative migration rate of the planet and particle, and the particle's eccentricity. Resonant capture fails for high migration rates, and has decreasing probability for higher eccentricities, although for certain migration rates, capture probability peaks at a finite eccentricity. We also calculate libration amplitudes and the offset of the libration centres for captured particles, and the change in eccentricity if capture does not occur. Libration amplitudes are higher for larger initial eccentricity. The model allows for a complete description of a particle's behaviour as it successively encounters several resonances. The model is applicable to many scenarios, including (i) Planet migration through gas discs trapping other planets or planetesimals in resonances; (ii) Planet migration through a debris disc; (iii) Dust migration through PR drag. The Hamiltonian model will allow quick interpretation of the resonant properties of extrasolar planets and Kuiper Belt Objects, and will allow synthetic images of debris disc structures to be quickly generated, which will be useful for predicting and interpreting disc images made with ALMA, Darwin/TPF or similar missions. Full details can be found in Mustill & Wyatt (2011).

Many stars are formed in some form of cluster or association. These environments can have a much higher number density of stars than the field of the galaxy. Such crowded places are hostile environments: a large fraction of initially single stars will undergo close encounters with other stars or exchange into binaries. We describe how such close encounters and exchange encounters will affect the properties of a planetary system around a single star. We define singletons as single stars which have never suffered close encounters with other stars or spent time within a binary system. It may be that planetary systems similar to our own solar system can only survive around singletons. Close encounters or the presence of a stellar companion will perturb the planetary system, leading to strong planet-planet interactions, often leaving planets on tighter and more eccentric orbits. Thus, planetary systems which initially resembled our own solar system may later more closely resemble the observed extrasolar planetary systems.

This paper is an abridged version of the report produced by the Blue Dots initiative, whose activities include the elaboration of a roadmap towards the spectroscopic characterization of habitable exoplanets. The full version of the Blue Dots report can be downloaded at http://www.blue-dots.net/spip.php?article105. While the roadmap will need to be updated regularly, it is expected that the methodology developed within Blue Dots will provide a durable framework for the elaboration of future revisions.

The Exoplanet Roadmap Advisory Team (EPR-AT) was formed by the European Space Agency (ESA) to advise it on the best path for characterizing exoplanets including terrestrial planets. The EPR-AT delivered its report to ESA in August 2010. Here we summarize the findings of this task force.

Every ten years the astronomy and astrophysics community in the United States undertakes a survey intended to prioritize plans for major ground- and space-based astronomical facilities for the coming decade. New Worlds, New Horizons (NWNH) was released in August 2010 and represents the community's advice to the United States' funding agencies about the top priorities for 2010-2020. Here we focus on the recommendations of NWNH for space-based exoplanet missions to be considered by NASA, and on the plans developed to date for how NASA will respond to the science goals and missions set out for them by NWNH.

The James Webb Space Telescope is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 ?m to 28 ?m. JWSTs primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. JWSTs instrument complement offers numerous capabilities to study the formation and evolution of exoplanets via direct imaging, high contrast coronagraphic imaging and photometric and spectroscopic observations of transiting exoplanets.

EPICS is the proposed planet finder for the European Extremely Large Telescope. EPICS is a high contrast imager based on a high performing extreme adaptive optics system, a diffraction suppression module, and two scientific instruments: an Integral Field Spectrograph (IFS) for the near infrared (0.95-1.65 μm), and a differential polarization imager (E-POL). Both these instruments should allow imaging and characterization of planets shining in reflected light, possibly down to Earth-size. A few high interesting science cases are presented.

The discovery of extrasolar planets is arguably the most exciting development in astrophysics during the past 15 years, rivalled only by the detection of dark energy. Two projects are now at the intersection of the two communities of exoplanet scientists and cosmologists: EUCLID, proposed as an ESA M-class mission; and WFIRST, the top-ranked large space mission for the next decade by the Astro 2010 Decadal Survey report. The missions are to have several important science programs: a dark energy survey using weak lensing, baryon acoustic oscillations, Type Ia supernova, a survey of exoplanetary architectures using microlensing, and different surveys. The WFIRST and EUCLID microlensing planet search programs will provide a statistical census of exoplanets with masses greater than the mass of Mars and orbital separations ranging from 0.5 AU outwards, including free-floating planets. This will include analogs of all Solar System planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, EUCLID and WFIRST's planet search programs will provide a complete statistical census of the planets that populate our Galaxy. As of today, EUCLID is proposed to ESA as a M class mission (the result of the selection will be known in october 2011). We are presenting here preliminary results about the expected planet yields. WFIRST has just appointed a Science Definition Team.

The PLAnetary Transits and Oscillations of stars (PLATO) mission is in its definition study phase in the context of ESA's Cosmic Vision 2015-2025 program. PLATO is applying for a launch in 2017/18. Its goal is to detect transiting exoplanets, including terrestrial planets in the habitable zone, and to determine their basic parameters with unprecedented accuracy. In combination with the detailed analysis of the stellar parameters by astroseismology and with ground-based follow-up observations, this will allow characterizing the main properties of exoplanetary systems to a level not achieved before.

The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?

In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.

The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.

EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.