Radial velocity, microlensing and transit surveys have revealed the existence of a large population of low-mass planets in our Galaxy, the so-called ‘Super-Earths’ and ‘Neptunes’. The understanding of these objects would greatly benefit from the detection of a few of them transiting bright nearby stars, making possible their thorough characterization with high signal-to-noise follow-up measurements. Our HARPS Doppler survey has now detected dozens of low-mass planets in close orbit around bright nearby stars, and it is highly probable that a few of them do transit their host star. In this context, we have set up an ambitious Spitzer program devoted to the search for the transits of the short period low-mass planets detected by HARPS. We present here this program and some of its first results.

Main sequence stars are commonly surrounded by disks of dust. From lifetime arguments, it is inferred that the dust particles are not primordial but originate from the collision of planetesimals, similar to the asteroids, comets and KBOs in our Solar system. The presence of these debris disks around stars with a wide range of masses, luminosities, and metallicities, with and without binary companions, is evidence that planetesimal formation is a robust process that can take place under a wide range of conditions. Debris disks can help us learn about the formation, evolution and diversity of planetary systems.

Spurred by the recent large number of radial velocity detections and the discovery of several transiting system and among those two planets, that are consistent with rocky composition, the study of planets orbiting nearby stars has now entered an era of characterizing massive terrestrial planets (aka super-Earths). One prominent question is, if such planets could be habitats. Here we focuss on one particular planet Gl581d. For Earth-like assumptions, we investigate the minimal atmospheric conditions for Gl581d to be potentially habitable at its current position, and if habitability could be remotely detected in its spectra. The model we present here only represents one possible nature an Earth-like composition - of a planet like Gl581d in a wide parameter space. Future observations of atmospheric features of such super-Earths can be used to examine if our concept of habitability and its dependence on the carbonate-silicate cycle is correct, and also assess whether Gl581d is indeed the first detected habitable super-Earth. We will need spectroscopic measurements to probe the atmosphere of such planets to break the degeneracy of mass and radius measurements and characterize a planetary environment.

Recently we were able to retrieve the Earth's transmission spectrum through lunar eclipse observations. This spectrum showed that the depth of most molecular species was stronger than models had anticipated. The presence of other atmospheric signatures, such as atmospheric dimers, were also present in the spectrum. We have been developing a radiative transfer code able to reproduce the Earth's transmission spectra at different depths into the penumbra and umbra, and taking into account transmission, refraction, and multiple scattering. Here we discuss the results to date and the work ahead.

Motivated by the increasing need for observational resources for the study of time varying astronomy, the Las Cumbres Observatory Global Telescope (LCOGT) is a private foundation, whose goal is to build a global network of robotic telescopes for scientific research and education. Once completed, the network will become a unique tool, capable of continuous monitoring from both the Northern and Southern Hemispheres. The network currently includes 2 × 2.0 m telescopes, already making an impact in the field of exoplanet research. In the next few years they will be joined by at least 12 × 1.0 m and 20 × 0.4 m telescopes. The increasing amount of LCOGT observational resources in the coming years will be of great service to the astronomical community in general, and the exoplanet community in particular.

During the last few years, observations have yielded an abundant population of short-period planets under 15 Earth masses. Among those, hot terrestrial exoplanets represent a key population to study the survival of dense atmospheres close to their parent star. Thermal emission from exoplanets orbiting low-mass stars will be observable with the next generation of infrared telescopes, in particular the JWST. In order to constrain planetary and atmospheric properties, we have developed models to simulate the variation of the infrared emission along the path of the orbit (IR phase curve) for both airless planets and planets with dense atmospheres. Here, we focus on airless planets and present preliminary results on the influence of orbital elements, planet rotation, surface properties and observation geometry. Then, using simulated noisy phase curves, we test the retrieval of planets' properties and identify the degeneracies.

As the number of known transiting planets from ground-based surveys passes the 100 mark, it is becoming possible to perform meaningful statistical analyses on their physical properties. Caution is needed in their interpretation, because subtle differences in survey strategy can lead to surprising selection effects affecting the distributions of planetary orbital periods and radii, and of host-star metallicity. Despite these difficulties, the planetary mass-radius relation appears to conform more or less to theoretical expectations in the mass range from Saturns to super-Jupiters. The inflated radii of many hot Jupiters indicate that environmental factors can have a dramatic effect on planetary structure, and may even lead to catastrophic loss of the planetary envelope under extreme irradiation. High-precision radial velocities and secondary-eclipse timing are yielding eccentricity measurements of exquisite precision. They show some hot Jupiters to be in almost perfectly circular orbits, while others remain slightly but significantly eccentric.

The purpose of the SEEDS project (PI: M. Tamura) is to conduct a direct imaging survey, searching for giant planets as well as protoplanetary/debris disks at a few to a few tens of AU regions around 500 nearby solar-type or more massive young stars with the combination of the Subaru 8.2m telescope, the new high-contrast instrument HiCIAO, and the adaptive optics system AO188. After instrument performance verification, the SEEDS survey successfully started in October 2009. We have already detected many companion candidates to be followed-up, and clear and much better detections of disks or details of known disks structures. In this contribution, we will outline our goal, current status, early results, and future instrumentation plans.

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.

In a recently published paper Matsumura et al. (2010) (hereafter M10), we have studied the evolution of three-planet systems in dissipating gas disks by using a hybrid N-body and one-dimensional gas disk evolution code. In this article, we highlight some results which are only briefly mentioned in M10.

The Earth's comparatively massive moon, formed via a giant impact on the proto-Earth, has played an important role in the development of life on our planet. Here we study how frequently Earth-Moon planetary systems occur. We derive limits on the collision parameters that may guarantee the formation of a circumplanetary disk after a protoplanet collision that could form a satellite. Based on a large set of simulations, we observe potential moon forming impacts and conclude that giant impacts with the required energy and orbital parameters for producing a binary planetary system occur frequently with more than one in ten terrestrial planets hosting a massive moon.

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.

Although a formation-flying space interferometer designed for exoplanet spectroscopy is feasible in principle, the novelty and cost of such an instrument is likely to remain daunting unless the scientific benefits of this technology are demonstrated by intermediary, precursor missions. Such instruments would represent intermediary steps in the real-life testing of the technology, and therefore, by the very reason of being intermediary, they may not have the resolving or collecting power needed for the study of the objects where biomarkers could be hoped to be detected, i.e., exo-Earths in the habitable zone of their stars. This paper examines the potential applications of such intermediary instruments. The direct line of thought focuses on exoplanetology (gas giants, protoplanetary discs, Neptunes, super-Earths, etc.); what we would like to stimulate is an exercise in lateral thinking, looking at what might an intermediary interferometric mission contribute to other fields of astrophysical research (galaxies, supernova precursors, planetary nebulae, molecular clouds, etc.). The paper raises the question of collaboration with astrophysicists studying areas other than exoplanets and its potential gains for the future of space interferometry.

We report the detection of a planetary companion around HIP 13044, a metal-poor red horizontal branch star belonging to a stellar halo stream that results from the disruption of an ancient Milky Way satellite galaxy. The detection is based on radial velocity observations with FEROS at the 2.2-m MPG/ESO telescope. The periodic radial velocity variation of P = 16.2 days can be distinguished from the periods of the stellar activity indicators. We computed a minimum planetary mass of 1.25 Mjup and an orbital semimajor axis of 0.116 AU for the planet. This discovery is unique in three aspects: First, it is the first planet detection around a star with a metallicity much lower than few percent of the solar value; second, the planet host star resides in a stellar evolutionary stage that is still unexplored in the exoplanet surveys; third, the planetary system HIP 13044 most likely has an extragalactic origin in a disrupted former satellite of the Milky Way.