The massive star clusters identified by S. Larsen are compared to the available Chandra observations of face-on spiral galaxies. In each galaxy, a few percent of the Larsen-identified clusters match X-ray-emitting point sources. An additional few match knots of emission in the diffuse emission. The cluster properties are examined to ascertain whether massive star clusters are X-ray sources.

Over 150 extrasolar planets are known to orbit sun-like stars. A growing number of them (9 to date) are transiting “hot Jupiters” whose physical characteristics can be measured. Atmospheres of two of these planets have already been detected. We summarize the atmosphere detections and useful upper limits, focusing on the MOST albedo upper limit and II exosphere detection for IID 209458b as the most relevant for photochemical models. We describe our photochemical model for hot Jupiters and present a summary explanation of the main results: a low gas-phase abundance of hydrocarbons; an absence of hydrocarbon hazes; and a large reservoir of II atoms in the upper atmospheres of hot Jupiters. We conclude by relating these model results to the relevant observational data.

This paper discusses the potential performances of interferometers at the Dome C site in the Antarctic. The work is focussed on the limiting performances for fringe tracking, considering different fringe trackers architectures. The fringe tracking limiting magnitude is combined with estimates of the isopistonic angle at Dome C to evaluate the possibilities of off axis fringe tracking. The first evaluations presented here indicate that the sky coverage with realistic off axis fringe tracking is quite high at Dome C even with modest individual apertures and this could finally the best and decisive advantage of this site for optical interferometry. This might make a Dome C interferometer an unique deep sky very high angular resolution machine.

We investigate the main differences between static 1D and 3D time-dependent model stellar atmospheres of red giants at very low metallicities. We focus in particular on the impact of 3D LTE spectral line formation on the derivation of elemental abundances for the extremely metal-poor ([Fe/H] $\approx-$5.3) red giant HE 0107-5240.

Search for the time variation of the fundamental constants is motivated by various unification theories. Here we present constraints on the variation of the fine-structure constant $\alpha$($\equiv {e^2/\hbar c}$) obtained using UVES/VLT samples of QSO absorption systems. We find ${<\Delta\alpha/\alpha}>_{w}={(-0.06\pm0.06)\times10^{-5}}$ using 23 Mg II systems and the many-multiplet (MM) method. Well selected 15 Si IV systems provide ${<\Delta\alpha/\alpha}>_{w}={(0.15\pm0.43)\times10^{-5}}$. Absence of detectable variation in $\alpha$ is also confirmed by our new very high resolution ($R\sim 100,000$) observation of $z_{\rm abs}=1.1508$ toward HE 0515–4414 using HARPS on the ESO 3.6m telescope.

We present preliminary oxygen abundances in a sample of four red-giants belonging to the bulge population. The abundances were derived from OH molecular transitions in the infra-red high-resolution spectra obtained with the Phoenix spectrograph on Gemini South. The target stars were taken from the previous study by McWilliam & Rich (1994) and selected in order to span a range in [Fe/H] from $-$1.0 to +0.5. Our oxygen results are found to be enhanced and fall above the Milky Way disk trend; in agreement with the high abundances obtained previously for other $\alpha-elements$. It is important to note, however, that the enhanced OH abundances obtained here are based upon stellar parameters taken directly from McWilliam & Rich (1994). Significant revisions to these published values are found more recently in McWilliam & Rich (2003) Such revisions would result in derived oxygen abundances that are systematically lower and perhaps in better agreement with the Milky Way trend. The conclusion is that further efforts are needed in order to better define the stellar parameters for the target stars, as they are crucial in order to decide the important issue of whether the oxygen abundances are enhanced in the bulge K-giants, as we find here. Or, on the other hand, if they follow the trend defined for the Milky Way disk.

In this review the present status of molecules in circumstellar envelopes of AGB stars is presented. Emphasis is put on the determination of abundances, and estimates of their uncertainties, from an observational point of view. Despite an impressive number of circumstellar species detected, about 60, there remains much work before general conclusions can be drawn. In particular, sophisticated radiative transfer modelling of circumstellar line emission must be done. This requires a detailed knowledge of the stellar and circumstellar properties, as well as basic molecular physics/chemistry data.

As is evident from Director Dan Green's detailed report below, the Central Bureau for Astronomical Telegrams (CBAT) continues to function in a very reliable and efficient way. The electronic telegrams (CBETs) introduced in 2002 have proved to be a great success; they allow for very rapid dissemination of more extensive information than there is room for on printed Circulars, and they are frequently cited in the astronomical literature. The workload on the Director seems to be forever increasing. It is therefore gratifying that an Assistant Director, Gareth Williams, has been appointed. Since he also serves as Associate Director of the Minor Planet Center (MPC) and performs many of the computations on which the CBETs and the Circulars are based, the ties and mutual benefits between the CBAT and the MPC have been made even stronger.

We investigate the 3-D matter distribution at $z\sim 2$ with high resolution ($R\sim 40,000$) spectra of QSO pairs and groups obtained with the UVES spectrograph at ESO VLT. Our sample is unique for the number density of objects and the variety of separations, between $\sim 0.5$ and 7 proper Mpc. We compute the real space cross-correlation function of the Lyman-$\alpha$ forest transmitted fluxes. There is a significant clustering signal up to $\sim 2$ proper Mpc, which is still present when absorption lines with high column density ($\log N \ge 13.8$) are excluded.

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.

Chandra observations have allowed the detection of a large number of low mass X-ray binaries (LMXBs) in early-type galaxies. Comparison to catalogs of globular clusters (GCs) from Hubble Space Telescope observations have shown that a high fraction of the LMXBs in early-type galaxies are associated with GCs. The fraction of LMXBs associated with globular clusters increases along the Hubble sequence from spiral bulges to S0s to Es to cDs. On the other hand, the fraction of globular clusters which contain X-ray sources appears to be roughly constant ($\sim$4% for $L_X \gtrsim 10^{38}$ ergs/s, $\sim$10% for $L_X \gtrsim 10^{37}$ ergs/s). There is a strong tendency for the X-ray sources to be associated with the optically more luminous GCs. There is a trend for the X-ray sources to be found preferentially in redder, more metal-rich GCs, which is independent of optical luminosity correlation.

The relative role of formation of LMXBs in GCs and in situ formation in the field is uncertain. One of the best ways to study this is to compare the spatial distribution of GC-LMXBs, field LMXBs, GCs, and optical light in the galaxies. Theoretical models and results of fits to the observed distributions are presented.

Recent observations demonstrate that dwarf galaxies in clusters, despite their faintness, may be a critical galaxy type for understanding the physical processes behind galaxy formation. Dwarfs are the most common type of galaxy and are particularly abundant in rich galaxy clusters. The dominate model for explaining the formation of these systems thorough Cold Dark Matter models is that the bulk of their stellar mass formed early, and within their present environments. Recent results however suggest that some dwarfs appear in clusters after the bulk of its members form, a scenario not predicted in standard hierarchical structure formation models. Many of these systems appear to be younger and more metal rich than dwarfs in lower density areas, suggesting they are possibly created by a tidal process induced by the cluster. Several general galaxy cluster observations, including steep luminosity functions and the origin of intracluster light, are natural outcomes of these processes.

Direct detection and spectral characterization of extrasolar planets is one of the most exciting but also one of the most challenging area in modern astronomy. For its second generation instrumentation on the VLT, ESO has supported two phase A studies for a so-called “Planet Finder” dedicated instrument. Based on the results of these two studies, a unique instrument is now considered for first light in early 2010, including a powerful extreme adaptive optics system, various coronagraphs, an infrared differential imaging camera, an infrared integral field spectrograph and a visible differential polarimeter. We will briefly summarize the science objectives and requirements, describe the proposed conceptual design and discuss the main limitations and corresponding instrumental issues of such a system. We will also derive the expected performance of the proposed Planet Finder and present the project organization.

Theoretical considerations lead to the expectation that stars should not have masses larger than about $m_{\rm max*}=60$–$120M_\odot$, while the observational evidence has been ambiguous. Only very recently has a physical stellar mass limit near $150M_\odot$ emerged thanks to modern high-resolution observations of local star-burst clusters. But this limit does not appear to depend on metallicity, in contradiction to theory. Important uncertainties remain though. It is now also emerging that star-clusters limit the masses of their constituent stars, such that a well-defined relation between the mass of the most massive star in a cluster and the cluster mass, $m_{\rm max}={\cal F}(M_{\rm ecl}) \le m_{\rm max*}\approx 150M_\odot$, exists. One rather startling finding is that the observational data strongly favour clusters being built-up by consecutively forming more-massive stars until the most massive stars terminate further star-formation. The relation also implies that composite populations, which consist of many star clusters, most of which may be dissolved, must have steeper composite IMFs than simple stellar populations such as are found in individual clusters. Thus, for example, $10^5$ Taurus–Auriga star-forming groups, each with 20 stars, will ever only sample the IMF below about $1M_\odot$. This IMF will therefore not be identical to the IMF of one cluster with $2\times 10^6$ stars. The implication is that the star-formation history of a galaxy critically determines its integrated galaxial IMF and thus the total number of supernovae per star and its chemical enrichment history. Galaxy formation and evolution models that rely on an invariant IMF would be wrong.

In da Silva et al. (2005) is presented the detailed spectroscopic analysis of 60 evolved stars, which were previously studied for accurate radial velocity variations (Setiawan et al. 2003). The observations were made with FEROS and the 1.52m ESO telescope of La Silla, partially in the ESO-Observatório Nacional (Brazil) agreement. The main goal of this study is to determine precise atmospheric fundamental data (Teff, log g, [Fe/H] and micro-turbulence velocity) to derive ages and masses of the stars, trying to link them to the detected radial velocity variabilities. Here, due the short space at our disposal, we discuss only the effective temperature determination, comparing the values obtained from the excitation equilibrium of FeI and from (V-K) index with those from (B-V).

A CCD survey of selected areas in the Virgo cluster was undertaken with the goal of finding dwarf ellipticals fainter in surface brightness than known in the Local Group. This was successful, and galaxies as much as 2 magnitudes fainter than e.g., Umi, have been found. These tend to be larger in radius, due to the detection methods, and thus more luminous than the LG as well. Two fields containing such galaxies were imaged with ACS/HST, with the result that individual RGB stars have been resolved in these galaxies, which are 15 Mpc distant.

We attempt to define the structural properties of Broad Absorption Line (BAL) QSOs and their relationship with the general quasar population using the Eigenvector 1 correlations. We identify 8 low-redshift quasars (z $<$ 0.5, 6 with a BALnicity index $>$ 0 km s$^{-1}$) where it was possible to combine optical and UV spectroscopic observations. The special utility of low-$z$ quasars involves our ability to discuss CIV$\lambda$1549 BAL QSOs in the context of the Eigenvector 1 optical parameter space and to have a reliable measure of the quasar rest frame. We find that the majority of the BAL sources are population A sources as defined in Sulentic et al. (2000). At least 2 sources that are hosted by ultra-luminous IR galaxies show intriguing effects in their nuclear spectra. A possible correlation between the terminal velocity and luminosity L also suggests that the luminosity to black hole mass ratio ($L/M$) is a governing factor with the largest terminal velocity BALs showing the highest $L/M$ values. The CIV$\lambda$1549 emission line profiles of classical BALs show the ubiquitous E1 population A blue-shift that supports a disk+wind scenario with an opening angle of $<$ 45$^\circ$. Observation of “secondary” BAL features roughly in correspondence with the mean radial velocity of the CIV$\lambda$1549 emission motivates us to model the BAL systems with an additional component that may share the BLR outflow and may be co-axial with the accretion disk, perhaps associated to a significant black hole spin.

A mid-infrared high-resolution spectral survey of the source IRC+10216 (CW Leo) has been carried out between 11 and 14 $\mu$m. A large number of lines of C$_2$H$_2$ and HCN and their most abundant isotopologues, have been identified. Lines involving high-energy ro-vibrational levels allow an accurate derivation of the physical and chemical conditions in the innermost envelope. We have developed a radiative transfer model capable of fitting the observed lines satisfactorily. The fit of more than 200 ro-vibrational lines allowed us to get the kinetic, vibrational and rotational temperatures and the abundances of the C$_2$H$_2$ and HCN between 1 and 300 R$_*$.

This triennial report from Comm. 14 covers the topics Atomic Spectra and Wave-length Standards, Atomic Transition Probabilities, Collision Processes, and Line Broadening.

We discuss the expected properties of the first stellar generations in the Universe. We find that it is possible to discern truly primordial populations from the next generation of stars by measuring the metallicity of high-z star forming objects through the detection and the study of the emission line spectrum from HII regions associated to primordial massive stars. Moreover, the intensity of HeII emission lines can be used as a diagnostic to reveal the presence of massive stars and determine their importance relative to lower mass stars. Thanks to its very low background, the future James Webb Space Telescope (JWST) will be able to image and study first-light sources at very high redshifts. On the other hand, JWST's relatively small collecting area limits its capability in obtaining spectra of z$\,{\sim}\,$10–15 first-light sources to either the bright end of their luminosity function or to strongly lensed sources. With a suitable investment of observing time JWST will be able to detect individual Population III supernovae, thus identifying the very first stars that formed in the Universe.