The Darwin and TPF-I missions are Infrared free flying interferometer missions based on nulling interferometry. Their main objective is to detect and characterize other Earth-like planets, analyze the composition of their atmospheres and their capability to sustain life, as we know it. Darwin and TPF-I are currently in study phase. A number of mission architectures of 3 and 4 free flying telescopes are evaluated on the basis of the interferometer's response, ability to distinguish multiple planet signatures and starlight rejection capabilities. The characteristics of the new configurations are compared also to the former, more complex Bowtie baseline architectures as well as evaluated on base of their science capability.

We have conducted a survey of X-ray sources in XMM-Newton observations of M31, examining their power density spectra (PDS) and spectral energy distributions (SEDs). Our automated source detection yielded 535 good X-ray sources; to date, we have studied 225 of them. In particular, we examined the PDS because low mass X-ray binaries (LMXBs) exhibit two distinctive types of PDS. At low accretion rates, the PDS is characterised by a broken power law, with the spectral index changing from $\sim$0 to $\sim$1 at some frequency in the range $\sim$0.01–1 Hz; we refer to such PDS as Type A. At higher accretion rates, the PDS is described by a simple power law; we call these PDS Type B. Of the 225 sources studied to date, 75 exhibit Type A variability, and are almost certainly LMXBs, while 6 show Type B but not Type A, and are likely LMXBs. Of these 81 candidate LMXBs, 71 are newly identified in this survey; furthermore, they are mostly found near the centre of M31. Furthermore, most of the X-ray population in the disc are associated with the spiral arms, making them likely high mass X-ray binaries (HMXBs). In general these HMXBs do not exhibit Type A variability, while many central X-ray sources (LMXBs) in the same luminosity range do. Hence the PDS may distinguish between LMXBs and HMXBs in this luminosity range.

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.

We present the results of analysis of “snapshot” spectra (i.e., R=20,000 and S/N=50 per pixel) of 253 metal-poor halo stars $-3.8<$[Fe/H]$<-1.5$ obtained in the HERES survey. The spectra are analysed using an automated line profile analysis method based on the Spectroscopy Made Easy (SME) codes of Valenti & Piskunov (1996). Elemental abundances of moderate precision (absolute r.m.s. errors of order 0.25 dex) have been obtained for 22 elements, C, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, and Eu, where detectable. The results are presented and discussed, particularly trends and scatter in the abundance distributions.

We present the results from a suite of N-body simulations of the tidal stripping of two-component dwarf galaxies comprising some stars and dark matter. We show that recent kinematic data from the local group dwarf spheroidal (dSph) galaxies suggests that dSph galaxies must be sufficiently massive ($10^9$–$10^{10}$M$_\odot$) that tidal stripping is of little importance for the stars. We discuss the implications of these massive dSph galaxies for cosmology and galaxy formation.

The interests of Division VII encompass the Milky Way Galaxy and it comprises two commissions: 33–Structure and Dynamics of the Galactic System and 37–Star Clusters and Association.

We describe the discovery of HE 1327–2326, a dwarf or subgiant with $\mbox{[Fe/H]}=-5.4$. The star was found in a sample of bright metal-poor stars selected from the Hamburg/ESO survey. Its abundance pattern is characterized by very high C and N abundances. The detection of Sr which is overabundant by a factor of 10 as compared to iron and the Sun, suggests that neutron-capture elements had already been produced in the very early Galaxy. A puzzling Li depletion is observed in this unevolved star which contradicts the value of the primordial Li derived from WMAP and other Li studies. Possible scenarios for the origin of the abundance pattern (Pop. II or Pop. III) are presented as well as an outlook on future observations.

In this paper I describe some of the recent advances made in the modelling of chemistry of protoplanetary disks, and in particular, of the inner regions where $r<100$ AU. These advances include the treatment of mass-transport processes, the interaction of radiation with chemistry, the augmentation of chemical networks to include isotopic species and their fractionation, and the attempt to connect disk chemistry with solar system bodies like comets. In the spirit of the title of this volume, I also briefly describe what in my opinion are the current challenges facing models of disk chemistry. These include the unification of chemistry, radiation and dynamics, the treatment of gas-grain interaction and the usefulness of observations to discriminate the different models in the literature.

The observational evidence for kinematic substructure in Local Group dSphs is reviewed. The properties of these substructures are consistent with their being disrupted star clusters. The persistence of cold substructure argues strongly against the presence of dark matter cusps in the haloes of dSphs. A formation scenario for dSphs is described involving the merger of star clusters in the potential well of a low-mass dark matter halo.

Using 24 overlapping XMM-Newton observations of the Local Group spiral galaxy M 33, we have detected 447 sources in each individual pointing and in deep combined images. A total of 61 sources exhibit significant flux variations by a factor of up to 144, on time scales of hours to months or years. The detected variability, together with the hardness ratio (HR) method and optical identification (when available), is used to classify the sources as X-ray binaries (XRBs), supernova remnants (SNRs) and super-soft sources (SSS) in M 33, as well as background AGN and foreground stars in the field of view. The majority of sources can only be classified as ‘hard’, according to their HRs. We find that the luminosity distribution of the detected SNRs and SNR candidates in M 33 is similar to M 31, and slightly steeper than that of the LMC.

We present new Keck/HIRES observations of seven of the highest-redshift known quasars. These include four with $z_{\rm qso}\ge 5.8$ and two with $z_{\rm qso}\ge 6.3$. The data will be used to produced a complete statistical description of the Ly$\alpha$ forest at $z > 5$, allowing us to better assess the significance of the strong absorption seen at $z>6.2$. We introduce the statistics of transmission gaps as a means of characterising the high-redshift evolution of the forest. In addition, we identify several clear absorption lines of low optical depth in the quasar proximity regions and briefly discuss using these to place constraints on the thermal history of the IGM at $z>5$.

The search for life on extrasolar planets is based on the assumption that one can screen extrasolar planets for habitability spectroscopically. The first space born instruments able to detect as well as characterize extrasolar planets, Darwin and terrestrial planet finder (TPF-I and TPF-C) are scheduled to launch before the end of the next decade. The composition of the planetary surface, atmosphere, and its temperature-pressure profile influence a detectable spectroscopic signal considerably. For future space-based missions it will be crucial to know this influence to interpret the observed signals and detect signatures of life in remotely observed atmospheres. We give an overview of biomarkers in the visible and IR range, corresponding to the TPF-C and TPF-I/DARWIN concepts, respectively. We also give an overview of the evolution of biomarkers over time and its implication for the search for life on extrasolar Earth-like planets. We show that atmospheric features on Earth can provide clues of biological activities for at least 2 billion years.

The commission supported the following IAU symposia and colloquia during the period 2002 to 2005: Dark Matter in Galaxies (IAUS220), Gravitational Lensing Impact on Cosmology (IAUS225); Transit of Venus: New Views of the Solar System and Galaxy (IAUC196); Populations of High-Energy Sources in Galaxies (IAUS230); Scientific Requirements for Extremely Large Telescopes (IAUS232).

Various physical processes are believed to trigger star formation on the borders of Galactic HII regions. Among these, the collect & collapse process is particularly attractive as it allows the formation of massive objects (single stars or clusters). In order to identify specific cases of this way of triggering star formation we are carrying out a multi-wavelength study of Galactic HII regions that exhibit signposts of massive-star formation at their borders. Hereby, we present two typical examples of such sources and discuss the results in the framework of the collect and collapse process, which seems to be at work as the major triggering agent in these two cases.

Metallicity may play an important role in the symbiotic phenomenon. Unfortunately, chemical abundances of symbiotic stars have been thus far poorly studied. Ongoing abundance analysis of a sample of over 30 symbiotic stars based on high-resolution, near-infrared spectra obtained with the Phoenix spectrometer on Gemini South telescope will allow for the first time to address properly the metallicity problem as well as provide important information about the past history of these binaries.

The recent development of large, complete samples which identify high-redshift galaxies at $z\sim5.7$ and $z\sim 6.5$ from deep, wide-field surveys provides detailed information on the earliest galaxies, their numbers, spatial and kinematic distributions, and implications for early reionisation of the IGM. In this contribution we present results of spectroscopic studies of $z\sim 5.7$ and $z\sim6.5$ galaxies identified from our deep, Lyman alpha narrow-band and multicolour surveys conducted with the SuprimeCam mosaic CCD camera on the 8.3-m Subaru telescope and observed with the DEIMOS multi-object spectrograph on Keck. The luminosity function of the $z\sim6.5$ galaxies is shown to be similar to the luminosity function of the $z\sim 5.7$ galaxy samples, suggesting that a substantial star-forming population is already in place at $z\sim 6.5$. Comparisons of both individual and stacked spectra of galaxies in these two samples show that the Lyman alpha emission profiles, equivalent widths, and continuum break strengths do not substantially change over this redshift interval. The wide-field nature of the surveys also permits mapping of the large-scale distribution of high-redshift galaxies in spatial structures extending across individual SuprimeCam fields ($\sim 60$ Mpc). Field-to-field variations in the number of objects at $z\sim 6.5$ may shortly be able to place constraints on the porosity of the reionisation boundary.

We discuss the fraction of carbon stars (C-stars) and of C-enhanced stars among samples of candidate extremely metal poor (EMP: [Fe/H] $\le -3.0$ dex) stars selected from the Hamburg/ESO Survey (HES), obtaining a total for C-rich stars with [C/Fe] $\ge$ +1.0 dex of 14.4$\pm4$%. We also present the key results of detailed abundance analyses of a sample of 14 C-stars selected in this way.

The recent discovery of hidden non-axysimmetric and disk-like structures in bright Virgo dwarf elliptical and lenticular galaxies (dE/dSph/dS0) indicates that they may have late-type progenitors. Using N-body simulations we follow the evolution of disk galaxies within a $\Lambda\textrm{CDM}$ cluster simulated with $10^7$ particles, where the hierarchical growth and galaxy harassment are modeled self-consistently. Most of the galaxies undergo significant morphological transformation, even at the outskirts of the cluster, and move through the Hubble sequence from late type disks to dwarf spheroidals. The time evolution of the simulated galaxies is compared with unsharp-masked images obtained from VLT data and the projected kinematics of our models with the latest high resolution spectroscopic studies from the Keck and Palomar telescopes.

As shown in our first poster, in a recent survey of M33 with XMM-Newton we detected the X-ray source population of this nearby spiral galaxy down to the (0.2-4.5) keV luminosity of $10^{35}$ erg s$^{-1}$, a factor of 10 deeper than in previous observations. The majority of the detected sources was classified using, in many cases, only their X-ray properties. In particular, 8 new X-ray binary (XRB) candidates were selected, based on their long-term X-ray light curves. We also classified supernova remnants (SNRs), super-soft sources (SSS), AGN, foreground stars and a population of ‘hard’ sources using the hardness ratio (HR) method. A detailed spectral and timing analysis of the brightest sources is in progress. We present a few examples of spectra for particular source classes. We find that bright ‘hard’ sources can be divided into two broad families: one best modelled by a powerlaw with photon index in the range of 1.0–2.0, and the other displaying disk blackbody spectra with kT of 0.8 to 1.5 keV.

We are conducting a survey of several regions of high-mass star formation to assess their content and structure. The observations include spitzer observations, ground-based optical and near-IR imaging surveys, and optical and IR spectra of objects and locations in the molecular clouds. The goal of the survey is to gain a better understanding of the processes involved in high mass star formation by determining the characteristics of the stars detected in these regions and investigating the properties of the interstellar medium (ISM) environment in which these stars form. In this contribution, we present results on the identification and spatial analysis of young stars in three clusters, W5/AFGL 4029, S255, and S235. First we show how the IRAC data are used to roughly segregate young stars according to their mid-infrared colors, into two groups corresponding the SED class I and class II young stellar objects. Then using the IRAC data in combination with 2MASS, we show how more young stars can be identified. Finally, we examine the spatial distributions of young stars in these clusters and find a range of morphologies and of peak surface densities.