Interpretative analyses of the X-ray emission from the giant starformation region R 136 have concluded that several colliding-wind binaries are likely to contribute to its X-ray output. Using our dedicated high-energy stellar population synthesis programme, we try to reproduce the suggested number of colliding-wind binaries. It appears that only assuming a very high binary fraction for the cluster's stellar population we can reproduce the observed X-ray luminosity distribution, if also the two most luminous sources are in fact multiple sources.

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.

We explore the X-ray diagnostics of cosmic star formation history that have possible form recent deep field X-ray studies. We summarize the status of our understanding of the X-ray evolution of galaxies. We indicate the lessons learnt so far from number count plots, and criteria for distinguishing between normal/straburst galaxies and AGNs in deep X-ray surveys. We summarize how the observed correlations between X-ray emission and that at other wavebands indicate the value of X-rays as a probe of cosmic star formation.

The study of C-enhanced metal poor stars with s-process elements overabundances offers a chance of testing the AGB models at low metallicity and constrain the nucleosynthesis codes. We analyzed a total of 13 C-enhanced metal poor stars, of which 12 turned out to be s-process enriched. The combination of our results with the analyses already published in the literature allows to highlight the discrepancies present between the current state of the art AGB low metallicity models, suggesting that they are still lacking some ingredient.

We present the results of population synthesis simulations aimed at exploring the evolution of the 2–10 keV luminosity of X-ray binaries in a young stellar population. The results are applicable to populations of extragalactic X-ray binaries in starburst galaxies and many LINERs. We find that the integrated 2–10 keV luminosity of the simulated population reaches a maximum of about $10^{40}\,{\rm erg~s}^{-1}$ after approximately 20 Myr (for a star-formation rate of 10 M$_{\odot}$ yr$^{-1}$) and remains significant even after the end of star formation and the demise of the luminous OB stars. The results of our simulation are in agreement with recently-derived correlations between the X-ray luminosity starburst galaxies and their star-formation rate. We also find that the cumulative luminosity function is initially fairly flat, in agreement with recent observational results, becoming steeper as the population ages and the high-mass X-ray binaries are succeeded by binaries with progressively lighter donor stars. Using the output of Hydrogen-ionizing far-UV photons from the stellar population, we can plot the track of a “post-starburst” system in the $L_{\rm X}-L_{\rm H\alpha}$ diagram. The system starts off in the starburst locus but quickly evolves to the AGN locus where it lingers for at least 1 Gyr.

Abundances of α-, iron peak, s- and r-elements were determined for a sample of Barium stars and the [α,iron peak/s], [α,iron peak/r], [s/r] ratios were derived.

Spectroscopic abundances of s- and r-process enriched very metal-poor stars are interpreted as the result of mass transfer in a binary system from an AGB companion assuming an initial composition of the parental cloud pre-enriched in r elements. The spectroscopic determination of [Na/Fe], [Mg/Fe] and [ls/Fe] permits an estimate of the initial AGB stellar mass, while a value [Zr/Nb] ≈ 0 is a nuclear indicator of an extrinsic AGB in a binary system.

This paper reviews the nature of normal and starburst galaxies in deep X-ray surveys, focusing on the observational issues. Normal and starburst galaxies may be divided from AGN via X-ray/optical flux ratios, optical spectroscopic identification, hardness ratio, and X-ray luminosity. Each of these is discussed, including the possible impact on derived X-ray-Star Formation Rate (X-ray/SFR) correlations. The measured differences in the normal galaxy X-ray Luminosity Functions (XLFs) by SED type at $z\approx0.3$–1.0 are also described.

The redshift frontiers of deep X-ray surveys are discussed, including those for individually detected accreting binary systems (Ultraluminous X-ray Sources at $z\approx0.1$–0.3) and that for the highest-redshift X-ray detection of star formation (stacking analyses of Lyman Break Galaxies to $z\approx4$). The paper closes with a discussion of normal galaxy studies with future X-ray missions such as Constellation-X, XEUS, and Generation-X.

Low mass AGB Stars are the main contributors to the Galactic s-process enrichment. We present new theoretical results obtained by adopting a full network from H to Bi coupled with the physical evolution of the stellar structure. We describe the formation of a 13C pocket as a consequence of H diffusion from the envelope into the He-rich intershell. Such 13C is burnt during the interpulse phase and provides the main neutron source in these stars. We computed two models with the same total mass (that is 2 M[odot ]) but two different initial chemical composition, namely (Y=0.269 – Z=0.015) and (Y=0.245 – Z=0.0001), representative of disk and halo stars respectively. We evaluate the differences in the final s-process surface composition and compare the results with the available observational data.

We have investigated 136 Chandra extragalactic sources without broad emission lines, including 93 NELG and 43 ALG. Based on $f_X/f_O$, $L_X$, X-ray spectral hardness and optical emission line diagnostics, we have conservatively classified 36 normal galaxies (20 spirals and 16 ellipticals) and 71 AGNs. Their redshift ranges from 0.01 to 1.2, while normal galaxies are at z=0.01–0.3. Our sample galaxies appear to share similar characteristics with local galaxies in terms of X-ray luminosities and spectral properties, as expected from the X-ray binary populations and the hot ISM. In conjunction with normal galaxies found in other surveys, we found no statistically significant evolution in $L_X/L_B$, within the limited z range ($<$0.1). We have built our log(N)-log(S) relationship of normal galaxies in the flux range, $f_X$ (0.5–8.0) = $10^{-15}$–$10^{-13}$ erg sec$^{-1}$ cm$^{-2}$, after correcting completeness by a series of simulations. The best-fit slope is −1.5 for both soft (0.5–2.0 KeV) and broad (0.5–8.0 KeV) energy bands, which is considerably steeper than that of AGN-dominated cosmic background sources at faint fluxes, but slightly flatter than the previous estimate, indicating normal galaxies will exceed in number over the AGN population at $f_X<10^{-18}$ erg sec$^{-1}$ cm$^{-2}$.

The great sensitivities of the Chandra X-ray Observatory and XMM-Newton are allowing us to explore the X-ray emission from galaxies at moderate to high redshift. By using the stacking method with CXO data, we show that we can detect the ensemble emission from normal elliptical, spiral and irregular galaxies out to redshifts approaching one. The average X-ray luminosity can then be compared with the results of models of the evolution in the numbers of X-ray binaries and can possibly be used to constrain models of star formation. In order to account for the increasing luminosity of spiral galaxies from low to moderate redshift, AGN components may need to be invoked.

We report the determination of the age of the Galactic thin disk by means of Th/Eu nucleocosmochronology. This method is only weakly dependent on stellar evolutions models, therefore allowing an important verification of the most used dating techniques, which are the fitting of isochrones to the oldest Galactic open clusters, and the calculation of white dwarf cooling sequences. This work builds upon our previous determination (del Peloso et al. 2005a, 2005b), by including 7 new objects to the sample which was originally composed of 19 disk dwarfs/subgiants of F5 to G8 spectral types – a 37% extension. The obtained result, (8.8±1.7)Gyr, corroborates the most recent white dwarf ages determined via cooling sequence calculations, which indicate a low age ($\widetilde{<}10~\mbox{Gyr}$) for the disk.

The living record of early Galactic nucleosynthesis is written in the chemical compositions of metal-poor stars. For stars with metallicities $-1.0 \geq $ [Fe/H] $\geq -2.5$, several decades of spectroscopic studies have delineated the abundance trends of elements that are synthesized by major nuclear fusion reaction chains. There is very strong observational evidence that the r-process isotopes identified in metal-poor stars and the solar system matter are in fact the product of two distinct types of r-process events. The observed pattern beyond Z [ges ] 40 up to Th-U should most likely be produced by only one (or a few) r-process event(s) in a unique stellar site. This “main” r-process then produces the “low-Z” elements (40 [les ] Z [les ] 48) under-abundant compared to solar, and reaches the full solar values presumably around Te.

Deep field observations are an essential tool to probe the cosmological evolution of galaxies. In this context, X-ray deep fields provide information about some of the most energetic cosmological objects: active galactic nuclei (AGN). Astronomers are interested in detecting sufficient numbers of AGN to probe the accretion history at high redshift. This talk gives an overview of the knowledge resulting from a highly complete soft X-ray selected sample collected with ROSAT, XMM–Newton and Chandra deep fields. The principal outcome based on X-ray luminosity functions and space density evolution studies is that low–luminosity AGN evolve in a dramatically different way from high–luminosity AGN: The most luminous quasars perform at significantly earlier cosmic times and are most numerous in a unit volume at cosmological redshift $z\sim2$. In contrast, low–luminosity AGN evolve later and their space density peaks at $z\sim 0.7$. This finding is also interpreted as an anti–hierarchical growth of supermassive black holes in the Universe. Comparing this with star formation rate history studies one concludes that supermassive black holes enter the cosmic stage before the bulk of the first stars. Therefore, first solutions of the so-called hen–egg problem are suggested. Finally, status developments and expectations of ongoing and future extended observations such as the XMM–COSMOS project are highlighted.

Observed large scatters in abundances of neutron-capture elements in metal-poor stars may suggest incomplete mixing of the interstellar medium at the beginning of the Galaxy. Comparing predictions by an inhomogeneous chemical evolution model and new observational results with Subaru HDS, we attempt to constrain the origins of r-process elements.

We present results of the X-ray spectral analysis of the $\sim$370 ksec deep survey obtained with XMM-Newton on the Chandra Deep Field South (CDFS). Using sample of 127 sources with redshift identifications and with a raw count limit of 100 (pn detector) we explored both the physical properties of individual sources, and the general properties of two AGN classes. The corresponding flux limits in the (0.5–2) and (2–10) keV bands are 1 $\times 10^{-16}$ and 9 $\times 10^{-16}$ erg cm$^{-2}$ s$^{-1}$, respectively. The average photon index is $\Gamma \sim$1.9 and $\Gamma \sim$1.8 for type-1 AGN and type-2 AGN, respectively. Although the properties of the spectra of more that 90% of AGN are in good agreement with the unified model, a fraction of ‘atypical’ objects (absorbed type-1 and unabsorbed type-2 AGN) was detected.

We present results from the hard X-ray sky survey being performed with INTEGRAL observatory. During two years of operation the significant sky area was covered with moderate sensitivity which now allows us to estimate surface number density of Active Galactic Nuclei (AGN) in hard (17-60 keV) energy band. Our catalog of detected sources comprises $>60$ AGN with wide range of intrinsic absorption. We used $24000 deg^{2}$ sky coverage (high Galactic latitude observations) with total exposure $>2$ Msec to derive source number-flux relation. The estimated surface density of extragalactic hard X-ray sources with flux $>10^{-11}$ erg s$^{-1}$ cm$^{-2}$ is $(1.0 \pm 0.5) 10^{-2} deg^{-2}$.

We present the even-to-odd Ba isotope ratios in 16 thick disk and 3 halo stars as determined from hyperfine structure (HFS) seen in the Ba II resonance line λ 4554. We find in our stars a higher fraction of the odd Ba isotopes compared with the solar one 18% (Cameron 1982): 35% in the halo stars and between 25% and 53% in the thick disk stars. There is a hint of increasing this value with the Eu/Fe abundance ratio growth. Based on the r-process even-to-odd Ba isotope ratio 54 : 46 (Arlandini, Käppeler, Wisshak, et al. 1999) we deduce the ratio of the s/r-process contribution to barium in the thick disk stars as 30 : 70 (±24%).

3C 273 is one of the brightest and best studied quasars. It has been observed for 770 ks with the imager IBIS (FoV 12 deg) on board INTEGRAL. To achieve the best possible S/N the dataset has been screened using several criteria indicating the quality of the data (i.e., number of good time intervals, etc). We describe the necessary tools and methods to analyze data of deep fields.

From Ge I lines in the near-ultraviolet, germanium abundances are deduced for the Sun, one metal-poor subgiant, and nine turnoff stars spanning a range of metallicities. The abundance of germanium with respect to iron varies widely among the stars, and is always at or below its solar proportion. In four stars, one mildly and the rest extremely metal-poor, Ge is deficient by [ges ]0.5 dex. The nearby elements Zn and Zr show nearly scaled-solar abundances. The Ge deficiency persists when heavy r-process elements such as platinum are extremely enhanced. Among this small sample, Ge deficiency correlates with Al deficiency, of similar size.