W UMa systems can be found everywhere in the Galaxy. They can be used as a distance tracer. Therefore, W UMa systems are very important to investigate the structure of the Galaxy. The distance to W UMa systems in globular clusters (GCs) is determined using a period–color–luminosity relation. It is found that the mean distance (ra) of W UMa systems is consistent with their host cluster distances (rGC) deduced from their intrinsic distance moduli if rGC ≤ 10 kpc. There is a significant difference between ra and rGC for rGC ≥ 10 kpc. We discuss the reasons causing this deviation.

The total and spectral irradiance varies over short time scales, i.e. from days to months, and longer time scales from years to decades, centuries, and beyond. In this talk we review the current understanding of irradiance changes from days to decades. We present the current status of observations and discuss proposed reconstruction approaches to understand these variations. The main question that ultimately needs to be answered is what are the physical processes that could explain the enhanced heating of the photosphere, chromosphere, transition region, and corona, leading to a change in the solar radiative output at various wavelengths. As semi-empirical models allow us to reproduce the solar spectrum over a broad wavelength range, they offer a powerful tool to determine the energy necessary to heat certain layers and at the same time balance the radiative losses.

The expansion speed of the Universe is increasing (Glanz 1998). This acceleration is attributed to dark energy which acts almost uniformly everywhere (including the Solar system) and thus essentially influences the Hubble constant. Its current value on a distance of 1 AU is H0 = 10 m/(yr AU). This is quite a large number and thus, the impact of dark energy should be detectable in the Solar system. We will illustrate it by several examples. Dark energy may partially be caused by gravitational aberration of the Sun, planets and other bodies.

The origin and evolution of stellar rotation has proven to be both important and challenging. Data obtained in star clusters has already provided key constraints on the role of protostellar disks and the timescales for angular-momentum loss and internal transport. Recent data sets also provide empirical support for the idea that a wide range of rotation rates converge on the main sequence. We evaluate the prospects for rotation–mass–age relationships and the role of open clusters in calibrating them.

A full understanding of the physical properties of integrated stellar systems demands a multiwavelength approach since each spectral window shows us the contribution of different types of stars. However, most of the observational effort in stellar population studies has been focused on the optical range. Now, the new generation of instruments allow us to explore the K band, where RGB and AGB stars dominate the light of the integrated spectra. Here we present a K-band spectroscopic analysis of early-type galaxies in different environments. Our sample comprises 12 field early-type galaxies observed with ISAAC at VLT with medium resolution, and they are compared with 11 Fornax cluster galaxies previously reported by Silva et al. (2008). The clear differences found in the infrared DCO and NaI indices between field and Fornax galaxies are discussed, trying to solve the puzzle formed by the near-infrared and optical measurements.

Ionization cones are one of the most important pieces of evidence supporting the AGN unified model (Antonucci & Miller 1985; Urry & Padovani 1995). Until now, the physical processes at work in the cones are not completely understood. A still open question concerns the origin of the gas. To study the origin of the ionized gas, we first selected a sample of nearby (z<0.03) Seyfert galaxies showing extended [O iii] λ5007 emission. We then observed these galaxies with the MultiPupil Fiber Spectrograph (MPFS) at the 6-m telescope of the Special Astrophysical Observatory (Russia). Here we present very preliminary results on the properties of the narrow-line region (NLR) of the intermediate Seyfert galaxy Mrk 6.

We have performed deep high-dispersion spectroscopy to examine enhancement of s-process elements in the exremely metal-poor ([Ar/H]~−2.1) halo planetary nebulae H4-1 and BoBn1 using the 8.2-m Subaru telescope/High-Dispersion Spectrograph (HDS). We have detected several emission lines of s-process elements in H4-1 and BoBn1, and we have found that the enhancement of heavy s-process elements in these objects is comparable with that in s-process enhanced CEMP stars with [Fe/H]>−2.5. The C- and N-rich abundances of H4-1 and BoBn1 might be explained by binary evolution models. We have detected 5 fluorine lines in BoBn1. The re-estimated F abundance using these lines is [F/H]=+1.4±0.1.

The expansion rate of the Universe can potentially be measured using age-dating of Luminous Red Galaxies (LRGs). Here, we explore the validity of the assumptions implicit in this method using LRGs identified in the Millenium Simulation (MS). We use stellar population modelling and spectral synthesis to estimate the errors on ages that can be expected and discuss optimization of such an experiment. We find that H(z) using simulated galaxies from MS can be recovered with high accuracy. Using single stellar populations (SSPs) to age-date LRGs is not sufficient but if the MS star formation histories of galaxies are used, accurate ages are obtainable. We discuss an observing program to carry out this experiment using SALT (Southern African Large Telescope).

In spite of its relevance, the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase is one of the most uncertain phases of stellar evolution, and a major source of disagreement between the results of different population synthesis models of galaxies. I will briefly review the existing literature on the subject, and recall the basic prescriptions that have been used to fix the contribution of TP-AGB stars to the integrated light of stellar populations. The simplicity of these prescriptions greatly contrasts with the richness of details provided by present-day databases of AGB stars in the Magellanic Clouds, which are now being extended to other nearby galaxies. I will present the first results of an ongoing study aimed at simulating photometry, chemistry, pulsation, mass loss, dust properties of AGB star populations in resolved and un-resolved galaxies. We test our predictions against observations from various surveys of the Magellanic Clouds (DENIS, 2MASS, OGLE, MACHO, Spitzer, and AKARI). I will discuss the implications and outline the plan of future developments.

To conclude this exciting conference on Stellar Populations: Planning for the Next Decade, we have sacrificed the traditional ‘conference summary’ for an opinion poll among all invited speakers on two issues: the most important achievements in the field of stellar populations over the past few years; and the most important challenges for the coming decade. The answers to this poll were remarkably uniform, indicating that the field of stellar populations has a clear future in the era when several new major research facilities are coming online.

In comparison with stellar magnetic field studies in the eighties and nineties, where most effort was focused on A, B, and active solar-type stars, magnetic fields are currently directly measured in massive early B and O stars with radiative envelopes, as well as in the lower mass tail consisting of fully convective late-M dwarfs. Knowledge of the magnetic field topology of stars of different mass and at different evolutionary stages is important to understand the underlying magnetic field generation mechanisms. I review the present status of magnetic field studies along with the results of theoretical modeling.

We demonstrate for the first time that gaseous halos of disk galaxies can play a vital role in recycling metal-rich gas ejected from the bulges and thus in promoting the chemical evolution of the disks. Our numerical simulations show that metal-rich bulge winds can be accreted onto the thin disks owing to hydrodynamical interaction between the gaseous ejecta and the gaseous halos. Accordingly, we anticipate that chemical abundances of the inner disk stars are significantly influenced by the enriched winds. About ~1% of gaseous ejecta from the bulges can be accreted onto the middle disk corresponding to the sun's position. We discuss these results in the context of the origin of super metal-rich stars in the solar neighborhood as well as an observed flattening of the abundance gradient in the Galactic disk.

We discuss evidence that quasars, and more generally radio jets, may have played an active role in the formation stage of galaxies by inducing star formation, i.e., through positive feedback. This mechanism first proposed in the 1970s has been considered as anecdotal until now, contrary to the opposite effect that is generally put forward, i.e., the quenching of star formation in massive galaxies to explain the galaxy bimodality, downsizing, and the universal black hole mass over bulge stellar mass ratio. This suggestion is based on the recent discovery of an ultra-luminous infrared galaxy, i.e., an extreme starburst, that appears to be triggered by a radio jet from the QSO HE 0450-2958 at z = 0.2863, together with the finding in several systems of a positional offset between molecular gas and quasars, which may be explained by the positive feedback effect of radio jets on their local environment.

The Heliospheric Imager (HI) instruments on board the two STEREO (Solar TErrestrial RElations Observatory) spacecraft provides an excellent opportunity for space based stellar photometry. The HI instruments provide a wide area coverage (20° × 20° for the two HI-1 instruments and 70° × 70° for the two HI-2 instruments) and long continuous periods of observations (20 days and 70 days respectively). Using HI-1A which has a pass band of 6500Å to 7500Å and a cadence of 40 minutes, we have gathered photometric information for more than a million stars brighter than 12th magnitude for a period of two years. Here we present some early results from this study on a range of variable stars and the future prospects for the data.

We present the visible spectrum of asteroid-comet transition object 133P/Elst-Pizarro (7968), the first member of the new population of objects called Main Belt Comets (Hsieh & Jewitt 2006). The spectrum was obtained with the 4.2m William Herschel Telescope at the “Roque de los Muchachos” observatory. The orbital elements of 133P place it within the Themis collisional family, but the observed cometary activity during it last 3 perihelion passages also suggest a possible origin in the trans-Neptunian belt or the Oort Cloud, the known sources of comets. We found a clear similarity between our spectrum of 133P and those of other members of the Themis family such as 62 Erato, and a strong contrast with those of cometary nuclei, such as 162P/Siding-Spring. This spectral comparison leads us to conclude that 133P is unlikely to have a cometary origin. This conclusion is strengthened by spectral similarities with activated near-Earth asteroid 3200 Phaethon, and suggest that there are activated asteroids in the near-Earth asteroid and main belt populations with similar surface properties.

We have observed 9 bright metal-poor stars whose kinematics suggest they are members of a stellar stream in the vicinity of the Solar neighborhood. These 9 stars exhibit no star-to-star dispersion in their [X/Fe] ratios for the α and Fe-peak elements, and the neutron-capture elements suggest mild enrichment by the main r-process. The abundance patterns seen in this stream are very similar to those found in the metal-poor globular cluster M15, and the kinematics of M15 are similar to those of the stream, suggesting that these two groups of stars may have shared a common origin.

Global warming in the troposphere and the decrease of stratospheric ozone concentration has become a major concern to the scientific community. The increase in greenhouse gases and aerosols concentration is believed to be the main cause of this global change in the lower atmosphere and in stratospheric ozone, which is corresponded by a cooling in the middle and upper atmosphere. However, there are natural sources, such as the sun and volcanic eruptions, with the same ability to produce global changes in the atmosphere. The present work will focus on solar variation and its signature in lower and middle atmosphere parameters. The Sun can influence the Earth and its climate through electromagnetic radiation variations and also through changes in the solar wind which causes geomagnetic storms. The effects of both mechanisms over the lower and middle atmosphere and ozone layer will be discussed through an overview of selected papers, which by no means cover this subject that is extremely wide and complex. A fundamental understanding of the atmosphere response to solar variations is required for understanding and interpreting the causes of atmospheric variability. This is an essential focus of climate science, which is seeking to determine the extent to which human activities are altering the planetary energy balance through the emission of greenhouse gases and pollutants.

In recent years. we have spectroscopically observed thousands of counterparts of selected ROSAT bright sources in the sacy project (Search for Associations Containing Young stars). We demonstrated that hundreds of the young stars found this way belong to nearby young, loose associations, some detected only in sacy, with ages in the range from 5 to 100 Myr. For their ages, these associations show no trace of their primitive nurseries, which poses some difficulties as to their origins. Nevertheless, there are some associations clearly associated with young open clusters, such as the ϵ Cha association (6 Myr) with the η Cha cluster, and the Argus association with IC 2391 (40 Myr). There seem to exist also more subtle connections, such as the AB Dor association (75 Myr) with the Pleiades. Here, we present evidence of the connections of young associations to open clusters, to understand their origin and their possible insertion in the cluster infant-mortality and Gould Belt scenarios.

Elements heavier than iron are produced in asymptotic giant branch (AGB) stars via the slow neutron capture process (s process). Recent observations of s-process-enriched Carbon Enhanced Metal-Poor (CEMP) stars have provided an unprecedented wealth of observational constraints on the operation of the s-process in low-metallicity AGB stars. We present new preliminary full network calculations of low-metallicity AGB stars, including a comparison to the composition of a few s-process rich CEMP stars. We also discuss the possibility of using halo planetary nebulae as further probes of low-metallicity AGB nucleosynthesis.