Cool, extrasolar gas giants similar to Jupiter and Saturn in our own Solar System should be detectable by virtue of the light they reflect in the optical and near-infrared with the next generation of Extremely Large Telescopes (ELTs) equipped with adaptive optics systems. Broad band imaging or very low-resolution spectra should then enable the characterization of the orbit, mass, atmospheric scattering properties, and presence of large rings in these gas giant analogues.

A highlight science case for the European ELT is: First light - The First Galaxies and the Ionization State of the Early Universe. It aims at understanding the formation and evolution of the first sources of light at the end of the Dark Ages and of the re-ionization of the Universe. The corresponding instrument requirements are: a few tens of integral field units with spatial sampling $\sim$20mas and individual fields of ${\sim}1''$ over a wide field of view of $5' \times 5'$ or larger. Multi-Object Adaptive Optics is required to locally provide significant image quality enhancement. Spectroscopic observations are required in the near IR domain with a spectral resolution of a few 1000. MOMFIS is a preliminary instrument concept designed for OWL around this science case. The instrument concept and preliminary design are presented. Development efforts are estimated, as well as development risks and required R&D activities.

Late-type giants (i.e., stars on the red and asymptotic giant branches, RGB/AGB, respectively) are dominant contributors to the overall spectral appearance of intermediate age and old stellar populations, especially in the red/near-infrared part of the spectrum. Being intrinsically bright, they are well suited for probing distant/obscured populations, especially those that can not be studied with their fainter members, like main sequence turn-off stars or subgiants. Late-type giants and supergiants will be the only stellar types accessible in intermediate age and old populations beyond the distances of several Mpc with the future 30-50 m class extremely large telescopes (Olsen et al. 2003). Indeed, proper understanding of their observable properties by means of theoretical models is of key importance for studying the evolution of stellar populations and their host galaxies.

Recent spectroscopic observation of $z=6.3$ GRB 050904 is reported with an emphasis on the importance of making similar prompt spectroscopy for long burst GRB events yet to come. A preliminary result of a survey for $z\sim7.0$ Lyman $\alpha$ emitters (LAEs) using a narrow band filter NBF973 is also presented.

Dwarfs of the spectral types late-M, L and T span mass regimes from very-low-mass stars through brown dwarfs down to young planetary objects. They all show massive molecular line-blanketing and the condensation of refractory species with decreasing $T_{\mathrm{eff}}$, leading to changes in chemical equilibrium composition and absorption due to dust grains. The spectral evolution from late-M through L to mid- and late-T classes is now understood as chiefly due to increasing amounts of condensates in the visible photosphere up to mid-L types, and the settling of dust clouds into deeper regions at the transition from L to T, resulting in a depletion of condensable elements in the upper atmosphere. The ensuing photospheric cooling also drives a change in carbon chemistry leading to the hallmark methane absorption features of T dwarfs.

Recent observations of brown dwarfs in the L-T spectral sequence and model atmosphere calculations have shown that these changes in spectral features reveal differences in the efficiency of cloud removal that seem to be triggered by an additional parameter besides effective temperature. We present models describing the settling of particle clouds as an equilibrium process between condensation, gravitational sedimentation and convective and turbulent mixing, based on 3D-hydrodynamical simulations for the description of the velocity field. These calculations predict a strong dependence of the settling on gravity, and can therefore explain observed differences between the spectral energy distributions of brown dwarfs of equal luminosity as an effect of different mass. Based on these calculations we would expect even stronger deviations in the colours of young brown dwarfs of very low mass from those commonly observed in the field. Such predictions seem to be in aggreement with the first observations of candidate planetary-mass objects, and would imply that extrasolar planets at very young ages have spectral energy distributions significantly different from previous models. Our models also predict characteristic time scales for the cloud formation processes that may be compared to observed variability in brown dwarfs.

I summarise the ELT requirements derived from the science cases in the area of galaxy formation/evolution and cosmology. This summary is based on the talks, posters and discussion in parallel Session A of this meeting, but also makes use of various publically-available ELT science case documents. Topics covered include studies of black holes, dark matter, properties of galaxies at a range of redshifts (including the first galaxies to form), fundamental constants and cosmology.

Both optical CCD detectors and infrared detector arrays have steadily evolved over the past 5 years, and have reached very satisfactory levels of quantum efficiency and dark current. Optical CMOS detector arrays have rapidly improved and are beginning to compete with CCD detectors. A new development of great relevance for future instrumentation is the integration of the readout electronics into an integrated circuit in close proximity to the detector, or, in the future, its vertical integration with the detector array and multiplexer. This paper reviews the present status of these technologies and identifies opportunities and risks for the next decade.

A key science driver for future ELTs is to chronicle the complete formation and evolutionary histories of a meaningful number of nearby galaxies through their resolved stars. The goal will be to measure the entire star formation and chemical enrichment histories of a sample of galaxies that includes all Hubble types and covers all of their components, demanding photometry of stars in regions with high surface brightness at distances of up to 20Mpc. We present simulations that compare the abilities of 20, 30, 50, and 100m telescopes to recover the correct stellar population mix represented in field star color-magnitude diagrams observed with $J$, $H$, and $K$ filters. As input, our simulations use scenes containing stars drawn from a mix of model isochrones with differing ages and metallicities, with surface densities set to match that found in the M31 bulge and at the effective radius of NGC 3379. We convolve these scenes with PSFs corresponding to the projected performance of MCAO systems containing two deformable mirrors, including the effect of realistic variations in the atmospheric turbulence profile over the span of the observations. These simulations provide a way to evaluate the scientific advances enabled by ELTs of differing apertures in the area of extragalactic stellar populations.

White dwarfs are excellent targets for direct imaging searches for extra-solar planets, since they are up to $10^4$ times fainter than their main sequence progenitors, providing a huge gain in the contrast problem. In addition, the orbits of planetary companions that lie beyond the maximum extent of the Red Giant envelope are expected to widen considerably, improving resolution and further encouraging direct detection. We discuss current searches for planetary companions to white dwarfs, including our own “DODO” programme. At the time of writing, no planetary companion to a white dwarf has been detected. The most sensitive searches have been capable of detecting companions ${\gtrsim}5$M$_{\rm Jup}$, and their non-detection is consistent with the conclusions of McCarthy & Zuckerman (2004), that no more than 3% of stars harbour 5–10M$_{\rm Jup}$ planets at orbits between 75–300AU. Extremely Large Telescopes are required to enable deeper searches sensitive to lower mass planets, and to provide larger target samples including more distant and older white dwarfs. ELTs will also enable spectroscopic follow-up for any resolved planets, and follow-up of any planetary companions discovered astrometrically by GAIA and SIM.

The combination of the collecting power of an ELT with an ultra-stable high resolution spectrograph opens up the possibility to measure for the first time directly the dynamical effect of the acceleration of the Universe. CODEX will also provide unique opportunities for advance in many other branches of astrophysics. The CODEX design is based on an array of several identical spectrographs. It is highly modular and can be easily adapted to a large range of sky apertures and telescope diameters. CODEX is designed to work as a seeing limited instrument. The requirements for the telescope are moderate and clearly identified.

The original Magellan partner institutions and the Smithsonian Astrophysical Observatory, Texas A&M University, and The University of Texas at Austin have undertaken to construct an extremely large telescope in Chile. The Giant Magellan Telescope is built around seven 8.4m borosilicate honeycomb mirror segments, six of which are off-axis. The collecting area is equivalent to that of a filled aperture 21.5m in diameter, the angular resolution is equivalent to a filled 24.4m telescope. The telescope mount is highly compact and delivers light to the focal plane in two reflections. Instruments are mounted at either a low-background straight Gregorian focus, or to one of several folded Gregorian foci behind the center primary mirror segment. A set of candidate first generation instruments has been defined and conceptual design studies are underway. The first off-axis primary mirror segment has been cast and will soon be polished as part of a proto-typing program. The current schedule calls for first light in mid 2015. This contribution describes the telescope and the considerations that led to its design.

Using the Lyman break technique (e.g., Steidel et al. 1995), large samples of star-forming galaxies at $2 \lt z \lt 5$ have been identified and studied. These Lyman break galaxies (LBGs) are UV-luminous and thought to be similar to local starburst galaxies; they are relatively small (r$_{h}$=1-3 kpc), have relatively low mass (10$^{9.5-11}$M$_\odot$) and low extinction. However, their role in galaxy evolution is still debatable. Do all galaxies go through a Lyman Break phase? How biased is our view of galaxy evolution due to the Lyman break technique? Are LBGs the building blocks of larger systems or just small galaxies having their first burst of star-formation? Therefore, a census of the star-forming galaxy population as a function of time is needed in order to help us better understand how galaxies acquired their present morphology. In this contribution, I discuss the physical properties of a sample of UV-selected galaxies at intermediate redshifts. I conclude by showing that galaxies of all types, sizes and shapes are forming stars at intermediate-z. However, deep image and spectroscopy with large telescopes are needed in order to properly address their nature.

We compare [$\alpha$/Fe], metallicity, and age distributions of globular clusters in elliptical, lenticular, and spiral galaxies, which we derive from Lick line index measurements. We find a large number of globular clusters in elliptical galaxies that reach significantly higher [$\alpha$/Fe] values ($>0.5$ dex) than clusters in lenticular and spiral galaxies. Most of these highly $\alpha$-enriched globular clusters are old ($t > 8$ Gyr) and exhibit relatively high metallicities up to solar values. Given the lower [$\alpha$/Fe] ratios of the diffuse stellar population in early-type galaxies, our results suggest that the extremely $\alpha$-enhanced globular clusters are members of the the very first generation of star clusters formed, and that their formation epochs likely predate the formation of the majority of stars in giant early-type galaxies.

The scientific goals for the TMT (Thirty Meter Telescope) are consistent with all the objectives outlined by the top level astronomy review committees in both Canada and the United States. In addition to powerful seeing-limited instruments, TMT will include instruments that will take advantage of the full diffraction-limited performance of a 30m telescope at wavelengths $\gt 1 \mu {\rm m}$. This will enable TMT to meet the challenges presented by the scientific requirements and will provide full complementarity with future project like JWST and ALMA. This paper presents a brief review of the status of TMT and an overview of the instruments and their adaptive optic systems.

Absorption lines of molecular hydrogen provide a most sensitive and powerful tool to understand the early evolution of galaxies and the intergalactic medium (IGM). In addition these lines are useful to investigate the space and time variations of the ratio of electron to proton mass. In this presentation I review the status of the search for H$_2$ at high $z$. High resolution spectrograph on ELTs will allow us to detect H$_2$ in the Lyman Break Galaxies (LBGs) and CO and HD in DLAs that already show H$_2$. This will allow us to investigate the astrochemistry at early epochs and study the physics of interstellar medium (ISM) at high redshifts.

Conventionally, CMD analyses of nearby star clusters are based on observations in 2 passbands. They are plagued by considerable degeneracies between age, metallicity, distance (and extinction) that can largely be resolved by including additional passbands with $U$ being most appropriate for young star clusters and I or a NIR band for old globular clusters. For star clusters that cannot be resolved, integrated photometry in suitably selected passbands was shown to be as accurate as spectroscopy in independently revealing ages, metallicities, internal extinction, and photometric masses and their respective 1$\sigma$ uncertainties, when analysed with a dedicated analysis tool for their Spectral Energy Distributions (=SEDs) (cf. Anders et al. 2004a, b, de Grijs et al. 2003b). For external galaxies, rich star cluster populations can thus be efficiently analysed using deep exposures in 4 suitable filters. Again, the inclusion of the $U$-band significantly reduces the uncertainties in the cluster parameters. The age and metallicity distributions of star cluster systems yield valuable information about the formation history of their parent galaxies (Fritze – v. Alvensleben 2004). Here, we present our GALEV evolutionary synthesis models for star clusters of various metallicities (Anders & Fritze - v. Alvensleben 2003), recently extended to include the time evolution of CMDs, the dedicated SED Analysis Tool AnalySED we developed, show results on the basis of HST data, and first results from our SALT PVP project on young star clusters in starburst and interacting galaxies.

The ESO strategy for short listing ELT candidate sites is reviewed: it uses a specially designed tool to allow the simultaneous use of existing databases with various relevant parameters.

The technical developments required to build the future Extremely Large Telescopes will be very demanding. Some of these developments, for instance in the field of Adaptive Optics, will rely on experimental work to test new techniques and concepts. The 4.2-m William Herschel Telescope located at a representative high-quality observing site, and with its stable Nasmyth optical bench for general access and its common-user Rayleigh laser beacon, is well placed to play a role as a testbed facility for such activities.

In this paper, we present a first comparison of different Adaptive Optics (AO) concepts to reach a given scientific specification for 3D spectroscopy on Extremely Large Telescope (ELT). We consider that a range of 30%–50% of Ensquarred Energy (EE) in H band (1.65$\mu$m) and in an aperture size from 25 to 100mas is representative of the scientific requirements. From these preliminary choices, different kinds of AO concepts are investigated: Ground Layer Adaptive Optics (GLAO), Multi-Object AO (MOAO) and Laser Guide Stars AO (LGS). Using Fourier based simulations we study the performance of these AO systems depending on the telescope diameter.

Using ROSAT seven isolated neutron stars have been discovered characterised by blackbody spectra at temperatures of 400-800 thousand K and the absence of radio and high energy emissions. Observations with Keck, HST and VLT show faint optical counterparts (m $\sim $ 24–29) with Rayleigh-Jeans-type spectra ($\sim\nu ^{2}$) and large proper motions. These objects are believed to be cooling neutron stars. They are of great interest from the point of view of neutron star astrophysics and nuclear physics. In particular, they allow us to measure neutron star radii and thus to constrain the equation of state at very high densities. We discuss the possibility of discovering larger samples of these objects with future sensitive X-ray sky surveys and follow-up optical observations with extremely large telescopes.