Cross-checking the reliability of various stellar spectral databases is an important and desirable exercise. Since number of stars in various databases have no known spectral types and some of the libraries do not have complete coverage resulting in gaps. We use an automated classification scheme based on Artificial Neural Networks (ANN) to cross-classify stars in the Indo-US stellar spectral library (Valdes et al. 2004), JHC (Jacoby, Hunter & Christian 1984), ELODIE spectra (Moultaka et al. 2004) and STELIB (Le Borgne et al. 2003). We have also examined the effects of over-training and over-fitting on the classification efficiency of a Neural Network. It is hoped that such a automated data analysis and validation technique will be useful in the future.

We have obtained deep images of the Local Group dwarf irregular galaxy Leo A using the Hubble Space Telescope Advanced Camera for Surveys. From these images we have constructed the deepest ever color-magnitude diagram (CMD) for an irregular galaxy beyond the Magellanic Clouds. We derive the star-formation rate (SFR) as a function of time over the entire history of the galaxy. We find that over 90% of Leo A's star formation has occurred more recently than 8 Gyr ago. Our measurements are not inconsistent with a scenario in which all of the ancient star formation occurred prior to the end of the era of reionization, with subsequent suppression until lookback times corresponding to redshift z ≈ 1. However, given Leo A's strongly isolated state and its dynamical mass of ≳ 108 M⊙, its large gas supply was more likely to have been merely heated than driven out of the galaxy altogether.

DE CVn is a relatively unstudied eclipsing binary where one of the components is an M dwarf and the other is a white dwarf. Its brightness makes it an ideal system for a detailed study in the context of common-envelope evolution of a detached white dwarf – red dwarf binary with a relatively short orbital period (∼8.7 hours). We present a detailed study of the basic parameters (e.g. orbital period, components' masses and spectral types) for this system from photometric and spectroscopic studies. The eclipses observed during several photometric observing runs were used to derive the ephemeris. We have used spectroscopic data to derive the radial velocity variations of the emission lines and these are used to determine the components' masses and the orbital separation. The secondary component in DE CVn is an M3 main-sequence star and the primary star, which only contributes to the blue continuum, is a cool white dwarf with a temperature of ∼8000 K. From the photometry and spectroscopy together, we have set a limit on the binary inclination. This system is a post-common-envelope system where the progenitor of the present day white dwarf was a low-mass star (M≤2M ⊙). The time before DE CVn becomes a semi-detached system is longer than the Hubble time.

Accretion disks in AGN should be subject to the same disk instability responsible for dwarf novae outbursts and soft X-ray transients in cataclysmic variables (CVs) and LMXBs. It has been suggested that this thermal/viscous instability can account for long term variability of AGNs. We analyze here the application of the DIM to the AGN case, using our adaptive grid numerical code developed in the context of CVs, enabling us to fully resolve the disk radial structure. We show that in AGNs, the width of heating and cooling fronts is so small that they cannot be resolved by standard codes, and that they propagate on time scales much shorter than the viscous time. As a result, transition fronts propagate back and forth in the disk, leading only to small luminosity variations. Truncation of the inner part of the disk by e.g. an ADAF will not alter this result, but enables the presence of quiescent states.

A summary of the round table discussion following Session A on Modelling Convection and Radiative Transfer is provided based on the video recording made during the conference.

We present the first study of bars in the local Universe, based on the Sloan Digitized Sky Survey (SDSS). The large sample of ~5000 local galaxies provides the largest study to date of local bars and minimizes the effect of cosmic variance. The sample galaxies have Mg ≤ −18.5 mag and cover the redshift range 0.01 ≤ z < 0.04. We use a color cut in the color-magnitude diagram and the Sérsic index n to identify disk galaxies. We characterize bars and disks using r-band images and the method of iterative ellipse fits and quantitative criteria developed in Jogee at al. (2004, ApJL, 615, L105). After excluding highly inclined (i>60°) systems our results are: (1) the optical (r-band) fraction of barred galaxies among local disk galaxies is 43% (Figure 1, left panel), which confirms the ubiquity of local bars, in agreement with other optical studies based on smaller samples (e.g. Eskridge et al 2000, AJ, 119, 536, Marinova & Jogee 2006, astro-ph/0608039); (2) the optical bar fraction rises for bluer galaxies, suggesting a relation between bars and star formation (Figure 1, middle panel); (3) preliminary analyzes suggest that the optical bar fraction increases steeply with the galaxy effective radius (reff, Figure 1, right panel); (4) the optical bar fraction at z ~ 0 is ~35% for bright disks (Mg ≤ −19.3 mag) and strong (bar ellipticity >0.4), large-scale (bar semi-major axis >1.5 kpc) bars, which is comparable to the value of ~30 ± 6% reported earlier (Jogee et al 2004) for similar disks and bars at z ~ 0.2 − 1.0.

We study the influence of shock X-ray emission on the structure of non-LTE wind models of O-type stars.

Young stellar objects (YSOs) inject large amounts of momentum and kinetic energy into their surroundings. Feedback from low mass YSOs is dominated by their outflows. However, as stellar mass increases, UV photo-heating and ionization play increasingly important roles. Massive stars produce powerful stellar winds and explode as supernovae within 3 – 40 Myr after birth. While low-mass protostellar feedback can drive turbulence in cloud cores and even disrupt the star forming environment, feedback from massive stars plays important roles in the generation of cloud structure and motions in the entire ISM.

Over the last few years there has been considerable progress in linking the published scholarly literature with on-line data. This will greatly help with data discovery and aid the efforts to the VO.

In dense stellar systems, dynamical interactions between objects inevitably lead to frequent formation of exotic stellar objects and multiple systems, thereby imposing new questions for the stellar evolution theory. The evolutionary path of such systems could be different from that of the unperturbed objects, therefore, we must re-evaluate their evolutionary treatment to clarify their consequent dynamical evolution. We review briefly the classes of important dynamical encounters and discuss several post-encounter outcomes that may require more detailed attention or development of a new treatment in stellar evolution: evolution of complex merger products, spun-up stars, binaries with stripped giants and triples.

We summarize the characteristics of 85 spectroscopic orbits derived from more than two decades of radial-velocity monitoring of stars in the old open cluster M 67, with special emphasis on the blue stragglers and other members that do not fall on the evolutionary tracks expected for isolated single stars.

A summary of the round table discussion following Session B on Observational Probes of Convection.

In the last decade, over 7000 eclipsing binaries have been discovered in the Local Group through various variability surveys. Measuring fundamental parameters of these eclipsing binaries has become feasible with 8 meter class telescopes, making it possible to use eclipsing binaries as distance indicators. Distances with eclipsing binaries provide an independent method for calibrating the extragalactic distance scale and thus determining the Hubble constant. This method has been used for determining distances to eclipsing binaries in the Magellanic Clouds and the Andromeda Galaxy and most recently to a detached eclipsing binary in the Triangulum Galaxy by the DIRECT Project. The increasing number of eclipsing binaries found by microlensing and variability surveys also provide a rich database for advancing our understanding of star formation and evolution.

We present the latest results of the survey searching for the nature of UV-selected galaxies in the Great Observatories Origins Deep Survey fields. By searching for UV-bright galaxies at intermediate redshifts (z ~ 1) we aim at understanding the nature of star-forming galaxies and their counterparts at higher-z, the so-called Lyman Break Galaxies.

We report a 3-dimensional numerical study of the accretion of stellar winds onto Sgr A*, the super-massive black hole at the centre of our Galaxy. Compared with previous investigations, we allow the stars to be on realistic orbits, include the recently discovered slow wind sources, and allow for optically thin radiative cooling. We first show the strong influence of the stellar dynamics on the accretion onto the central black hole. We then present more realistic simulations of Sgr A* accretion and find that the slow winds shock and rapidly cool, forming cold gas clumps and filaments that coexist with the hot X-ray emitting gas. The accretion rate in this case is highly variable on time-scales of tens to hundreds of years. Such variability can in principle lead to a strongly non-linear response through accretion flow physics not resolved here, making Sgr A* an important energy source for the Galactic centre.

Recent observations in the mid-infrared (5-25 μm) of massive young stellar sources have yielded a surprising result: many show evidence of mid-infrared emission from outflows and jets. These observations correlate well with other larger-scale outflow indicators and their geometries, such as what is seen in shock-excited H2 and CO emission. In some cases these mid-infrared observations identify the local maser emission as outflow or jet related.

The state and discovery rate of current NEO surveys reflect incremental improvements in a number of areas, such as detector size and sensitivity, computing capacity, detection software efficiency and availability of larger telescope apertures. The result has been an increase in the NEO discovery rate. There are currently eight telescopes ranging in size from 0.5-1.5 meters carrying out full-or part-time systematic surveying in both hemispheres. The sky is covered 1-2 times per lunation to V1~9, with a band near the ecliptic to V2~0.5. We review the current survey programs and their contributions towards the Spaceguard goal of discovering at least 90% of the NEOs larger than 1 km.

In keeping with its co-sponsorship by members of both the “close” and “wide” binary star communities, IAU Symposium 240 has been jointly dedicated to the honor of Czech astronomer Mirek J. Plavec and the memory of U.S. astronomer Charles E. Worley.

About one core-collapse supernova (CCSN) is expected to explode every 5–10 years in the nuclear regions of M 82 and other nearby starburst galaxies. In luminous infrared galaxies (LIRGs) such as the interacting system Arp 299 (NGC 3690 + IC 0694) at least one CCSN can be expected every year. Due to the high dust extinction most of these SNe have remained undetected. Here we show results from two near-IR searches we have recently carried out to detect obscured SNe in nearby starburst galaxies and LIRGs.

Current and near future all-sky astrometric catalogs on the ICRF are reviewed with the emphasis on reference star data at optical wavelengths for user applications.