We present a heuristic model for the collisional evolution of material in a debris disk. This is used to consider the probability that the 2-3% brightness clump observed in the sub-mm Fomalhaut disk is caused by stochastic collisions between large planetesimals. While this simple model finds that the probability that the clump is caused by collisions is low (about 1 in 80,000), a more detailed model is required to ascertain its true likelihood.

Here we report a study of formation of protoplanetary with radiation of SiO maser from Orion-IRC2 using a new model, i.e. the distinct multiple rotating and expanding disc-rings of Orion-IRC2 SiO (ν =1, J-2-1) maser for explanation of the fact that the several small peaks superposed the double-peaked spectral profile and the relative position map.

We describe the two main techniques by which planetary systems may be imaged, and by which spectra of the planets may be obtained. There is a discussion of how planetary systems will appear, and of the extreme differences in brightness between stars and their planets Coronography is an extension of Lyot's technique by addition of adaptive optics. Nulling is an interferometric technique originally proposed by Bracewell. Differences between the techniques are emphasized. The paper concludes with a discussion of the problem of training people to develop these technically difficult tasks.

In this article, we discuss the instrumental requirements for planet searches from the ground. We review several methods and their fundamental limitations comparing the direct measurement of the visibility function (both modulus and phase) to astrometry and nulling interferometry. In particular, we will take the Very Large Telescope Interferometer (VLTI) as an example. The VLTI is an excellent facility for planet searches from the ground since it has both large apertures and long baselines, providing high SNR and milli-arcsecond resolution.

The space mission COROT can be considered as a DARWIN/TPF precursor, since it will contribute to the pre-DARWIN/TPF effort with its dedicated exoplanet program. COROT will survey more than 50 thousands stars, each one during five months, in order to detect transits of planets. Despite of the modest size of the telescope, the photon-noise limited performances may lead to the detection of several tens of “hot jupiters” and, more important, of a few planets of the Earth-Uranus class, i.e. with a size of typically 1.5 to 4 Earth radius. In the basic mode of operation (characterization of a planet by at least 3 detected transits), only planets with a short orbital period, and thus rather “hot” ones (T = 600K), should be discovered. However, one of the COROT's features is its capability to provide a wavelength dependent information, thanks to a prism in the optical path.

The goal of finding and characterizing habitable planets in other solar systems represents one of humanity's greatest scientific challenges. NASA and ESA have initiated studies of missions that could accomplish this goal within the next ten years. What precursor knowledge do we need before we can initiate such a mission? How large should the first steps be in a program whose ultimate aim is to detect life on other planets? This talk describes different concepts for NASA's Terrestrial Planet Finder and discusses potential precursors in a program that balances scientific return, technological advance, and programmatic risk.

The next generation millimeter to submillimeter wavelength synthesis telescope, the Atacama Large Millimeter Array (ALMA), is an excellent instrument for direct and indirect detection of extrasolar giant planets and imaging of extrasolar planetary systems at all evolutionary stages. We examine some possibilities of ALMA in this respect here.

The recent photometric detection of planetary transits of the solar-like star HD 209458 at a distance of 47 parsecs suggest that transits can reveal the presence of Jupiter-size planetary companions in the solar neighborhood (Charbonneau et al. 2000; Henry et al. 2000). Recent space-based transit searches have achieved photometric precision within an order of magnitude of that required to detect the much smaller transit signal of an earth-size planet across a solar-size star. Laboratory experiments in the presence of realistic noise sources have shown that CCDs can achieve photometric precision adequate to detect the 9.6 E-5 dimming of the Sun due to a transit of the Earth (Borucki et al. 1997; Koch et al. 2000). Space-based solar irradiance monitoring has shown that the intrinsic variability of the Sun would not preclude such a detection (Borucki, Scargle, Hudson 1985). Transits of the Sun by the Earth would be detectable by observers that reside within a narrow band of sky positions near the ecliptic plane, if the observers possess current Earth epoch levels of technology and astronomical expertise. A catalog of solar-like stars that satisfy the geometric condition for Earth transit visibility are presented.

Eddington is a space mission for extrasolar planet finding and for asteroseismic observations. It has been selected by ESA as an F2/F3 reserve mission with a potential implementation in 2008-13. Here we describe Eddington's capabilities to detect extrasolar planets, with an emphasis on the detection of habitable planets. Simulations covering the instrumental capabilities of Eddington and the stellar distributions in potential target fields lead to predictions of about 10,000 planets of all sizes and temperatures, and a few tens of terrestrial planets that are potentially habitable. Implications of Eddington for future larger scale missions are briefly discussed.

The DARWIN project is ESA's candidate mission for the search for extra-solar Earth-type planets. Its aims are to survey the closest stars for these planets, and if detected characterise them as what concerns their physical conditions, their atmospheric composition and their ability to host life as we know it.

We present a new test for the direct detection of extra-solar planets that relies on the presence of a strong molecular absorption band in the thermal emission from the planetary atmosphere. This signature will be sought by the method of differential astrometry, in which the astrometric centroid positions are compared in and out of the molecular band.

N = RsfpneflfifcL. This well known Drake equation denoting the number N of civilizations in the Galaxy, includes a factor fp that is the fraction of stars that have planetary systems, and another factor ne that is the mean number of planets suitable for life. The latter is usually understood as the number of planets within the habitable zone. When the Solar system remained a unique object of its kind the sense of fp and ne seemed to be clear. There is now a limited statistic in hand about the features of other planetary systems, permitting a rough estimation of fp and ne (based on the list of 32 star companions, compiled by G. Marcy, 14.02.2000).

We have undertaken an adaptive optics imaging survey of extra-solar planetary systems and stars showing interesting radial velocity trends from high precision radial velocity searches. Adaptive Optics increases the resolution and dynamic range of an image, substantially improving the detectability of faint close companions. This survey is sensitive to objects less luminous than the bottom of the main sequence at separations as close as 1″. We have detected stellar companions to the planet bearing stars HD 114762 and Tau Boo. We have also detected a companion to the non-planet bearing star 16 Cyg A.

We report first results from our ground-based infrared imaging search for sub-stellar companions (brown dwarfs and giant planets) of young (up to 100 Myrs) nearby (up to 100 pc) stars, where companions should be well separated from the central stars and still relatively bright due to ongoing accretion and/or contraction. Our observations are performed mainly with SOFI and SHARP at the ESO 3.5m NTT on La Silla (imaging) and with ISAAC at the ESO 8.2m Antu (VLT-UT1) on Cerro Paranal (imaging and spectroscopy), all in the H- and K-bands. Here, we present new companion candidates1 around three T Tauri stars (TWA-8 A, RXJ1121.1-3845, and RXJ1121.3-3447 N) in the TW Hya group, which would have been sub-stellar if at the same distance and age as the T Tauri stars, but are found to be background stars by spectroscopy.

Within the next few years three microsatellites with part-per-million photometric capability (MOST, MONS, COROT) will be launched. These space telescopes, which were designed for asteroseismology, as well as other proposed or planned space telescopes to detect Earth-like transiting planets (Kepler and Eddington), will be able to observe the reflected light curves of the close-in extrasolar giant planets (CEGPs). The CEGPs are 0.05 AU from their parent star and are potentially bright in reflected light. For a transiting planet (at any orbital distance) moons and planetary rings may be detected.

We discuss the development of the “Differential Phase” detection technique for the Keck Interferometer “Hot Jupiter” Key Science Program. The goal of the “Hot Jupiter” Key Science Program is the direct detection and infrared, low-resolution spectroscopic characterization of previously detected, T ≥ 1000 K extra-solar planets. Although many extra solar planets are sufficiently bright to detect with large telescopes, the proximity of these planets to the much brighter stellar primary makes direct detection difficult because of angular resolution and intensity dynamic range limitations. The Keck Interferometer, working in the near infrared, has sufficient angular resolution and sensitivity to detect some of the currently known extra solar planets; however, the intensity dynamic range required (∽1:30, 000) is substantially beyond the capability of the traditional techniques of optical and infrared direct-detection interferometers.

SIM - the Space Interferometry Mission - will be the first of a new generation of space instruments using interferometry. Designed for precision astrometry, it will be a 10-meter optical interferometer providing 4 microarcsecond (μas) absolute position measurements over the whole sky, using a grid of stars (and quasars) for a reference frame. Maintaining its astrometric precision on stars as faint as 20 magnitude, it will far surpass the capability of ground-based astrometry, opening up a new era of space-based astrometry. A wide range of astrophysics problems will be addressed by SIM, including formation and dynamics of our Galaxy, calibration of the cosmic distance scale, and fundamental stellar astrophysics. SIM will search for planetary companions to nearby stars, by detecting the well-known astrometric ‘wobble’ signature with a single-measurement precision of 1 μas, enabling the detection of planets down to about an Earth mass. SIM will serve as a technology pathfinder for NA8A's Terrestrial Planet Finder. Launch is currently planned for 2008, with a mission duration of 5 years.