Many recent observational studies have concluded that planetary systems commonly exist in multiple-star systems. At least ~20%, and presumably a larger fraction, of the known extrasolar planetary systems are associated with one or more stellar companions. These stellar companions normally exist at large distances from the planetary systems (typical projected binary separations are 102–104 AU) and are often faint (ranging from F to T spectral types). Yet, secular cyclic angular momentum exchange with these distant stellar companions can significantly alter the orbital configuration of the planets around the primaries. One of the most interesting and fairly common outcomes seen in numerical simulations is the opening of a large mutual inclination angle between the planetary orbits, forced by differential nodal precessions caused by the binary companion. The growth of the mutual inclination angle between planetary orbits induces additional large-amplitude eccentricity oscillations of the inner planet due to the quadrupole gravitational perturbation by the outer planet. This eccentricity oscillation may eventually result in the orbital decay of the inner planet through tidal friction, as previously proposed as Kozai migration or Kozai cycles with tidal friction (KCTF). This orbital decay mechanism induced by the binary perturbation and subsequent tidal dissipation may stand as an alternative formation channel for close-in extrasolar planets.

Strong tidal interaction with the central star can circularize the orbits of close-in planets. With the standard tidal quality factor Q of our solar system, estimated circularization timescales for close-in extrasolar planets are typically shorter than the age of the host stars. While most extrasolar planets with orbital radii a ≲ 0.1 AU indeed have circular orbits, some close-in planets with substantial orbital eccentricities have recently been discovered. This new class of eccentric close-in planets implies that either their tidal Q factor is considerably higher, or circularization is prevented by an external perturbation. Here we constrain the tidal Q factor for transiting extrasolar planets by comparing their circularization times with accurately determined stellar ages. Using estimated secular perturbation timescales, we also provide constraints on the properties of hypothetical second planets exterior to the known eccentric close-in planets.

Observations using the Spitzer Space Telescope provided the first detections of photons from extrasolar planets. Spitzer observations are allowing us to infer the temperature structure, composition, and dynamics of exoplanet atmospheres. The Spitzer studies extend from many hot Jupiters to the hot Neptune orbiting GJ436. Here I review the current status of Spitzer secondary eclipse observations, and summarize the results from the viewpoint of what is robust, what needs more work, and what the observations are telling us about the physical nature of exoplanet atmospheres.

We present limits on transit timing variations and secondary eclipse depth variations at 8 microns with the Spitzer Space Telescope IRAC camera. Due to the weak limb darkening in the infrared and uninterrupted observing, Spitzer provides the highest accuracy transit times for this bright system, in principle providing sensitivity to secondary planets of Mars mass in resonant orbits. Finally, the transit data provides tighter constraints on the wavelength-dependent atmospheric absorption by the planet.

Transiting planets are generally close enough to their host stars that tides may govern their orbital and thermal evolution. We present calculations of the tidal evolution of recently discovered transiting planets and discuss their implications. The tidal heating that accompanies this orbital evolution can be so great that it controls the planet's physical properties and may explain the large radii observed in several cases, including, for example, TrES-4. Also, since a planet's transit probability depends on its orbit, it evolves due to tides. Current values depend sensitively on the physical properties of the star and planet, as well as on the system's age. As a result, tidal effects may introduce observational biases in transit surveys, which may already be evident in current observations. Transiting planets tend to be younger than non-transiting planets, an indication that tidal evolution may have destroyed many close-in planets. Also the distribution of the masses of transiting planets may constrain the orbital inclinations of non-transiting planets.

We have now entered a phase of extrasolar planets characterization: probing their atmospheres for molecules, constraining their horizontal and vertical temperature profiles and estimating the contribution of clouds and hazes. We review here the current situation with ground-based and space-based observations, and present the transmission spectra of HD189733b in the spectral range 0.5-24 microns.

We show that a consistent fit to observed secondary eclipse data for several strongly irradiated transiting planets demands a temperature inversion (stratosphere) at altitude. Such a thermal inversion significantly influences the planet/star contrast ratios at the secondary eclipse, their wavelength dependences, and, importantly, the day-night flux contrast during a planetary orbit. The presence of the thermal inversion/stratosphere seems to roughly correlate with the stellar flux at the planet. Such temperature inversions might be caused by an upper-atmosphere absorber whose exact nature is still uncertain.

We highlight the potential importance of gaseous TiO and VO opacity on the highly irradiated close-in giant planets. The day-side atmospheres of these planets may naturally fall into two classes that are somewhat analogous to the M- and L-type dwarfs. Those that are warm enough to have appreciable opacity due to TiO and VO gases we term the “pM Class” planets, and those that are cooler, such that Ti and V are predominantly in solid condensates, we term “pL Class” planets. The optical spectra of pL Class planets are dominated by neutral atomic Na and K absorption. We discuss a connection between temperature inversions and large day/night temperature contrasts for the pM Class planets. Around a Sun-like primary, for solar composition, this boundary likely occurs at ~0.04-0.05 AU, but we discuss important uncertainties. The difference in the observed day/night contrast between υ And b (pM Class) and HD 189733b (pL Class) is naturally explained in this scenario.

We present new observations of the emission spectrum of the hot Jupiter TrES-4 designed to test the theory that the presence of temperature inversions in the atmospheres of these planets are correlated with the amount of radiation received by the planet. Our observations reveal that TrES-4 has an emission spectrum similar to that of HD 209458b, which requires the presence of an inversion layer high in the atmosphere and water emission bands in order to explain the observed features, providing additional support for that theory. We also present new observations of the thermal phase curve of HD 189733b at 24 μm, which we combine with our previous observations at 8 μm to examine how circulation in this planet's atmosphere varies as a function of depth. We discuss the relationship between the strength of the day-night circulation on both planets and their other observable properties, in particular their emission spectra.

Extrasolar super-Earths (1-10 M⊕) are likely to exist with a wide range of atmospheres. While a number of these planets have already been discovered through radial velocities and microlensing, it will be the discovery of the first transiting super-Earths that will open the door to a variety of follow-up observations aimed at characterizing their atmospheres. Super-Earths may fill a large range of parameter space in terms of their atmospheric composition and mass. Specifically, some of these planets may have high enough surface gravities to be able to retain large hydrogen-rich atmosphseres, while others will have lost most of their hydrogen to space over the planet's lifetime, leaving behind an atmosphere more closely resembling that of Earth or Venus. The resulting composition of the super-Earth atmosphere will therefore depend strongly on factors such as atmospheric escape history, outgassing history, and the level of stellar irradiation that it receives. Here we present theoretical models of super-Earth emission and transmission spectra for a variety of possible outcomes of super-Earth atmospheric composition ranging from hydrogen-rich to hydrogen-poor. We focus on how observations can be used to differentiate between the various scenarios and constrain atmospheric composition.

Transiting planets provide a unique opportunity to study the atmospheres of extra-solar planets. Radiative hydrodynamical models of the atmosphere provide a crucial link between the physical characteristics of the atmosphere and the observed properties. Here I present results from 3D simulations which solve the full Navier-Stokes equations coupled to a flux-limited diffusion treatment of radiation transfer. Variations in opacity amongst models leads to a variation in the temperature differential across the planet, while atmospheric dynamics becomes much more variable at longer orbital periods. I also present 3D radiative simulations illustrating the importance of distinguishing between optical and infrared opacities.

Here we describe the observations and the resulting constraints on the upper atmosphere (thermosphere and exosphere) of hot Jupiters. In particular, observations and theoretical modeling of hot-Jupiter evaporation are described. The observations allowed the discovery that the planet orbiting HD209458 has an extended atmosphere of escaping hydrogen and showed the presence of oxygen and carbon at very high altitude. These observations give unique constraints on the escape rate and mechanism in the atmosphere of these planets. The most recent Lyman-alpha HST observations of HD189733b allow for the first time to compare the evaporation from two different planets in different environments. We present models to quantify the escape rate from the measured occultation depths, and an energy diagram to describe the evaporation state of hot Jupiters. Using this diagram, it is shown that few already known planets could be remnants of former giant planets.

The Kepler Mission is a space-based mission whose primary goal is to determine the frequency of Earth-size and larger planets in the habitable zone of solar-like stars. The mission will monitor more than 100,000 stars for patterns of transits with a differential photometric precision of 20 ppm at V = 12 for a 6.5 hour transit. It will also provide asteroseismic results on several thousand dwarf stars. It is specifically designed to continuously observe a single field of view of greater than 100 square degrees for 3.5 or more years.

This paper provides a short overview of the mission, a brief history of the mission development, expected results, new investigations by the recently chosen Participating Scientists, and the plans for the Guest Observer and Astrophysical Data Programs.

The NASA Discovery mission EPOXI, utilizing the Deep Impact flyby spacecraft, comprises two phases: EPOCh (Extrasolar Planet Observation and Characterization) and DIXI (Deep Impact eXtended Investigation). With EPOCh, we use the 30-cm high resolution visible imager to obtain ultraprecise photometric light curves of known transiting planet systems. We will analyze these data for evidence of additional planets, via transit timing variations or transits; for planetary moons or rings; for detection of secondary eclipses and the constraint of geometric planetary albedos; and for refinement of the system parameters. Over a period of four months, EPOCh observed four known transiting planet systems, with each system observed continuously for several weeks. Here we present an overview of EPOCh, including the spacecraft and science goals, and preliminary photometry results.

Oscillations occur in stars of most masses and essentially all stages of evolution. Asteroseismology is the study of the frequencies and other properties of stellar oscillations, from which we can extract fundamental parameters such as density, mass, radius, age and rotation period. We present an overview of asteroseismic analysis methods, focusing on how this technique may be used as a tool to measure stellar properties relevant to planet transit studies. We also discuss details of the Kepler Asteroseismic Investigation – the use of asteroseismology on the Kepler mission in order to measure basic stellar parameters. We estimate that applying asteroseismology to stars observed by Kepler will allow the determination of stellar mean densities to an accuracy of 1%, radii to 2–3%, masses to 5%, and ages to 5–10% of the main-sequence lifetime. For rotating stars, the angle of inclination can also be determined.

A variety of new observational opportunities have made transit and more generally light curve analysis central to the study of exoplanets. Talks at this IAU 253 Symposium have dramatically highlighted the measurement of the radius, density, atmospheric composition and atmospheric thermal structure, presently for relatively large, hot planets, but soon for smaller planets orbiting further from their host stars. On-going and future space observations will play a key role in the detection and characterization of these planetary systems. After a brief review, I focus on two topics: the need for a sensitive all-sky survey for planets transiting the brightest, closest stars and the follow-up opportunities afforded by the James Webb Space Telescope (JWST).

WHAT is a small-aperture short focal length automated telescope with an 8.2° × 8.2° field of view, located at the Wise Observatory, Israel. The system is similar to the HATNet telescopes and is aimed at searching for transiting extrasolar planets and variable objects. Operational since 2004, WHAT has accumulated ~100000 exposures of several fields and was part of the discovery of the transiting planet HD147506b. Further description of WHAT can be found at: http://wise-obs.tau.ac.il/~what.

SuperLupus is a deep transit survey monitoring a Galactic Plane field in the Southern hemisphere. The project is building on the successful Lupus Survey, and will double the number of images of the field from 1700 to 3400, making it one of the longest duration deep transit surveys. The immediate motivation for this expansion is to search for longer period transiting planets (5-8 days) and smaller radii planets. It will also provide near complete recovery for the shorter period planets (1-3 days). In March, April, and May 2008 we obtained the new images and work is currently in progress reducing these new data.

ASTEP South is the first phase of the ASTEP project that aims to determine the quality of Dome C as a site for future photometric searches for transiting exoplanets and discover extrasolar planets from the Concordia base in Antarctica. ASTEP South consists of a front-illuminated 4k × 4k CCD camera, a 10 cm refractor, and a simple mount in a thermalized enclosure. A double-glass window is used to reduce temperature variations and the associated turbulence on the optical path. The telescope is fixed and observes a 4° × 4° field of view centered on the celestial South pole. With this design, A STEP South is very stable and observes with low and constant airmass, both being important issues for photometric precision. We present the project, we show that enough stars are present in our field of view to allow the detection of one to a few transiting giant planets, and that the photometric precision of the instrument should be a few mmag for stars brighter than magnitude 12 and better than 10 mmag for stars of magnitude 14 or less.

The Tautenburg Exoplanet Search Telescope (TEST) is a robotic telescope system. The telescope uses a folded Schmidt Camera with a 300mm main mirror. The focal length is 940mm and it gives a 2.2° × 2.2° field of view. Dome, mount, and CCD cameras are controlled by a software bundle made by Software Bisque. The automation of the telescope includes selection of the night observing program from a given framework, taking darks and skyflats, field identification, guiding, data taking, and archiving. For the search for transiting exoplanets and variable stars an automated psf photometry based on IRAF and a lightcurve analysis based on ESO-Midas are conducted. The images and the results are managed using a PostgreSQL database.