The paper focuses on the issues for detection of life by remote observations. The problem is divided into the detection of terrestrial planets and the detection of life on them. The problem of detection of planets is compared with the observations of the Hubble Deep Field. The difficulty of detection will likely result in many interesting discoveries before detection techniques are adequate. It is proposed that life is the activity of mutually assisting persistence processes. A persistence process is one that uses the Gibbs Free Energy of the environment for repair and development. It is pointed out that because life produces approximations to equilibrium it is intrinsically difficult to detect by remote observations. Chemical signs of life will be distinctive if the abiotic processes that might produce them are implausible, and preferably absent. The ease of remote detection of terrestrial life is contrasted with problems likely to arise for other planets. It is recommended that initial searches be focused on giant planets. The spectral region of the discovery observations will be set by technical issues which are not yet resolved for any technique. For determining whether life is present, as many spectral regions as possible should be observed.

Neuhäuser et al. (2005a) presented evidence for a sub-stellar, common proper motion companion to GQ Lup, which is almost certainly a planet imaged directly, based on two independent mass estimates by means of theoretical models. The magnitude of GQ Lup b was determined by relative photometry compared to GQ Lup A. During a one-month monitoring of the primary star, we found is to be a variable with K= 6.9 to 7.3 mag (absolute photometry). Then, we re-observed GQ Lup A+b in May 2005, again with VLT/NACO. Due to the monitoring in April 2005, we could predict the exact K-band magnitude range of the primary during the new AO observation. Hence, we could determine a more precise error of the K-band magnitude of GQ Lup b by relative photometry compared to the primary. The new value is consistent with the previous estimate within the error margin, so that also the conclusions in Neuhäuser et al. (2005a,b) about its very low mass remain valid.

We present procedures and preliminary results from a study on the effects of instrumental polarization on the fine structure of the stellar point spread function (PSF). These effects are important to understand because the the aberration caused by instrumental polarization on an otherwise diffraction-limited will likely have have severe consequences for extreme high contrast imaging systems such as NASA's planned Terrestrial Planet Finder (TPF) mission and the proposed NASA Eclipse mission. The report here, describing our efforts to examine these effects, includes two parts: 1) a numerical analysis of the effect of metallic reflection, with some polarization-specific retardation, on a spherical wavefront; 2) an experimental approach for observing this effect, along with some preliminary laboratory results. While the experimental phase of this study requires more fine-tuning to produce meaningful results, the numerical analysis indicates that the inclusion of polarization-specific phase effects (retardation) results in a point spread function (PSF) aberration more severe than the amplitude (reflectivity) effects previously recorded in the literature.

Superjupiters are much brigther when they are young and still contracting, and the contrast with the harboring stars is significantly more favorable for their detection. Within the JOVIAN (Jupiter-like Objects in the Visible and the Infrared: Astrophysical Nature) project, a search has been performed for superjupiters around nearby young stars using 4 m class telescopes. Here we summarize the results and present prospects for a future search around young and also relatively older nearby stars with the 10 m Gran Telescopio Canarias and the mid-infrared camera CanariCam.

Many methods have been proposed for the detection of exoplanets. The minimum detectable planetary size and mass, and the maximum distance from us at which exoplanets are observable, are determined by both technological and environmental constraints. The unique atmospheric conditions found at Dome C offer significant advantages. Using what is now known about the turbulence profile of the atmosphere above Antarctic plateau sites, we explore the potential these sites offer for detecting exoplanets around nearby stars using various methods.

This paper presents the status of the EPICS project, an Earth-like Planets Imaging Camera Spectrograph for OWL. We present the Top-Level-Requirements of the instrument and we describe the baseline of the Adaptive Optics system with optimized wave-front sensor. The expected performance in rejection of starlight in the near infrared and in the visible is given. The instruments concepts for detection and characterization of exo-planets will be briefly described. The Signal-to-Noise ratio estimation shows that Earth-like planets can be detected up to 20 pc in a reasonable amount of time. The extremely challenging requirements in terms of static residual errors and differential aberrations are discussed.

The Lyot coronagraph can achieve significant on-axis starlight suppression when equipped with a notch filter image mask. Notch filter masks are placed in the focal plane and have small intricate features. They must be manufactured using nanofabrication techniques, when designed for coronagraphs operating at visible or near infrared wavelengths. This process often involves depositing an opaque material onto a glass substrate whereby a pattern is then etched. The substrate however can be a source of internal reflections and chromatic aberrations that limit the coronagraph's dynamic range and broadband performance. We present theoretical and experimental work on a new series of image masks that do not require the support of a glass substrate. We show that by adding periodic bar structures of appropriate spacing, it may be possible to manufacture a Silicon binary notch filter mask that is “free-standing”.

The space mission PEGASE, proposed to the CNES (Centre National d'Etudes Spatiales = French Space Agency) in the framework of its call for scientific proposals : “formation flying missions”, is a 2-aperture interferometer, composed by 3 free flying satellites (2 siderostats and 1 beam combiner), allowing baselines from 50 to 500 m in both nulling and visibility modes. With an angular resolution of a few mas and a spectral resolution of several tens in the spectral range 2.5-5 microns, PEGASE has several goals:

1. science : spectroscopy of hot jupiters (Pegasides) and brown dwarves, exploration of the inner part of protoplanetary disks

2. technology : validation in real space conditions of formation flying, nulling and visibility interferometry concepts.

Nulling interferometry is one of the promising techniques for the study of extra terrestrial planets. This technique will be applied in the future space missions Darwin and TPF-I, and from the ground with GENIE. The nulling interferometry techniques require high symmetry of the interfering beams, to obtain the required contrast (typically $10^6$ to detect terrestrial exo-planets in the thermal infrared). In this paper we consider the polarization symmetry issue, such as polarization rotation and polarization phase shifts occurring on slightly misaligned optics. We study the consequences of these symmetry requirements on a nulling interferometer design. We find the relation between the misalignment tolerances and the achievable nulling, and we show that this tolerance is highly dependent on the interferometer configuration (the way beams turn right, left, up or down in the interferometer arms). It is typically of the order of the arcminute (not the arcsecond) for a $10^6$ contrast. We present a analytical and numerical analyses.

In principle, band-limited coronagraphic image masks are capable of removing all on-axis starlight providing infinite dynamic range for the direct imaging of exoplanets. In practice, optical aberrations left uncorrected by the adaptive optics system and practical limitations on mask alignment prevent band-limited masks from reaching contrast levels necessary for exoplanet imaging. So-called, “high-order” band-limited masks reduce the coronagraph's sensitivity to low order aberrations, and have been measured to reach contrast levels of $10^{-7}$ at $4\, \lambda/D$ without the aid of a deformable mirror. In this work, we simulate the performance of high-order band-limited coronagraphic image masks in a variety of adaptive optics systems. We compare their performance with that of hard-edge stops, soft-edge Gaussian masks, and traditional (4th-order) band-limited coronagraphs.

In order to evaluate and develop mission concepts for a search for Terrestrial Exoplanets, the European Space Agency has prepared a list of potential target systems. In this paper we present the criteria for selecting potential target stars suitable for the search for Earth like planets. We also establish the habitable zone for the stellar systems. Planets found within these zones would be potentially able to host complex life forms. The Darwin target star catalogue was created from the Hipparcos catalogue by examining the information on distance, spectral classification, multiplicity and stellar variability. Additional information on the targets stars including spectral type, metallicity, X-ray luminosity, rotation and Strömgren photometry from several other catalogues are included to determine the target star sample. Design constraints of the mission are added to derive a final target star catalogue of 262 target stars excluding and 447 target stars including M stars for the Darwin mission. We also discuss the completeness of sample for different classes of stars.

This has been a wonderful conference, in a beautiful setting, with many of the world's planet-seekers on hand to present their ideas, at a time when we stand technically almost ready to embark on designing space missions to search for Earth-like planets and signs of life on them. In these remarks, I wish to simply list the ‘big questions’ that face us today, and offer some personal comments on how we might address these questions.

For a bit of inspiration from the past, I will close with a parallel that might be drawn between the journey that we all wish to embark upon, to search for extrasolar planets and to characterize them, and the one described by John Bunyan in his 1678 allegory, Pilgrim's Progress.

A remarkable aspect of this conference has been the agreement on our common goal, to detect and characterize extrasolar planets. While it is true that various of us suscribe to different theories of how planetary systems are formed, or how to best build the telescopes that can investigate these planetary systems, nevertheless we do all believe that the next great frontier in astrophysics is the study of extrasolar planets, and in particular Earth-like planets.

The topic of this conference can be phrased in terms of the following ‘big questions’. Are there Earth-like planets around nearby stars? Are these planets habitable? Do they show signs of life?

These questions generate many sub-questions that we need to answer. In the following I list the questions as I see them today. I will phrase them in terms that can be easily understood by most of the public. Doubtless you will have other questions, but this is a start.

Visible Nulling Coronagraphy (VNC) is the proposed method of detecting and characterizing exo-solar Jovian planets (null depth $10^{-9}$) for the proposed NASA's Extrasolar Planetary Imaging Coronagraph (EPIC) Clampin & Lyon 2004 and is an approach under evaluation for NASA's Terrestrial Planet Finder (TPF) mission. The VNC approach uses a single unobscured filled-aperture telescope and splits, via a 50:50 beamsplitter, its re-imaged pupil into two paths within a Mach-Zender interferometer. An achromatic PI phase shift is imposed onto one beam path and the two paths are laterally sheared with respect to each other. The two beams are recombined at a second 50:50 beamsplitter. The net effect is that the on axis (stellar) light is transmitted out of the bright interferometer arm while the off-axis (planetary) light is transmitted out of the nulled interferometer arm. The bright output is used for fine pointing control and coarse wavefront control. The nulled output is relayed to the science camera for science imagery and fine wavefront control. The actual transmission pattern, projected on the sky, follows a $\theta^2$ pattern for a single shear, $\theta^4$ for a double shear, with the spacing of the successive maxima proportional to the inverse of the relative lateral shear. Combinations of shears and spacecraft rolls build up the spatial frequency content of the sky transmission pattern in the same manner as imaging interferometer builds up the spatial frequency content of the image.

We present ground-based disc resolved polarimetric imaging and spectropolarimetry of Uranus and Neptune in the wavelength range from 530 to 930 nm with the goal to constrain the expected polarization of extra-solar planets with similar atmospheric properties. We find for both planets a high limb polarization as expected for atmospheres with significant Rayleigh scattering layers. The limb polarization is enhanced in the strong methane absorption bands when compared to the adjacent continuum. From the observed polarization features we conclude that extra-solar planets with atmospheric properties similar to Uranus and Neptune are strongly polarized and well suited for polarimetric detection and investigation.

The search for extraterrestrial technology effectively began 45 years ago with Frank Drake's Project Ozma and a radioastronomy start to the search for extraterrestrial intelligence (SETI). Eventually searches began for possible interstellar probes in stable orbits in the Solar System, as well as for infrared excesses from possible Dyson spheres round Sun-like stars. Whilst the Cold War was still underway, some scientists looked for evidence of nuclear waste dumps and nuclear wars elsewhere in the Milky Way. None of this work was carried out by archaeologists, even though by their very nature archaeologists are experts in the detection of ancient technologies. The technologies being searched for would have been partly ancient in age though advanced in techniques and science. The development of ESA's Darwin and NASA's TPF for detection and imaging of Earth-like exoplanets in our galactic neighbourhood represents an opportunity for the testing of techniques for detecting signatures of technological activities. Ideally, both Darwin and TPF might be able to provide spectroscopic data on the chemistry and biochemistry of the atmospheres of Earth-like exoplanets, and thus to detect some of the signs of life. If this can be accomplished successfully, then in theory evidence for pollution and nuclear accidents and wars should be detectable. Some infrared signatures of ETT on or round exoplanets might be detectable. Direct visual imaging of ETT structures will probably not be feasible till we have extremely powerful interstellar telescopes or actually send orbital craft.

Creating an optical space telescope observatory capable of detecting and characterizing light from extra-solar terrestrial planets poses technical challenges related to extreme wavefront stability. The Terrestrial Planet Finder Coronagraph design team has been developing an observatory based on trade studies, modeling and analysis that has guided us towards design choices to enable this challenging mission. This paper will describe the current flight baseline design of the observatory and the trade studies that have been performed. The modeling and analysis of this design will be described including predicted performance and the tasks yet to be done.

Discriminating exo-planetary photons from stellar photons with a ground-based instrument is a physically interesting and challenging issue. We propose an observational technique based upon both spectral and polarimetric coding to discriminate the exo-planetary photons. We also discuss a preliminary observation run performed with the spectrograph “CARELEC” on the 193 cm telescope at the Observatoire de Haute provence (OHP).

I will discuss the connection between the luminosity function of a population of high-mass X-ray binaries in a galaxy and the star formation rate in the this galaxy. The understanding of this connection provides on the one hand an independent measure of an important galaxy property, and on the other hand new insights into populations of high-mass X-ray binaries. In particular, observations with the Chandra X-ray telescope are uniquely suited to investigate the X-ray part of this connection and I will present examples of this.

We review progress in the area of the modelling of shocks in molecular clouds. In particular, we consider what has been learnt about shock structure evolution in situations where the steady-state assumption is no longer valid. We discuss the interpretation of the observed water abundance from SWAS, Odin, and ISO. We also consider the erosion of grains in shocks as well as the effect of the presence of grains on shock structure.

We present time-resolved spectroscopy from the January 2005 outburst of the X-ray nova XTE J1118+480. X-ray observations show this outburst to be about half as bright as the previous outburst in 2000. This suggests that the accretion rate was lower than that in the 2000 outburst. Our spectroscopic analysis shows that the emission from the H$\alpha$ line occurs at a higher velocity in the recent outburst compared with the 2000 outburst, more consistent with quiescence/near-quiescence values. This is surprising, considering the $\sim$5 magnitude brightening of the accretion disk relative to its quiescent state.