Galactic open clusters are excellent laboratories to study stellar populations that are coeval and have a common chemical composition. These clusters allow for the investigation of stellar and chemical abundance evolution, binary star systems, mass and luminosity functions, Galactic metallicity gradient, and disk structure, among other things. The Southern Open Cluster Study (socs) is a database of a select set of 24 open clusters with a broad range of ages and metallicities. It is an extension of the northern WIYN Open Cluster Study (wocs). The main goal of both studies is to obtain comprehensive photometric, spectroscopic, and astrometric information of these key open clusters. Here, we provide an overview of the socs survey and present results of the wide-field photometry on two socs clusters, NGC 3532 and Tombaugh 2.

In many of the “wonders” of our past, information about their meaning and scope has been encoded in the form of astronomical alignments to celestial bodies. Therefore, in many cases, understanding the ideas of the ancient architects turns out to be connected with the study of the relationship of their cultures with the sky. This is the aim of archaeoastronomy, a discipline which is a quite efficacious tool in unraveling the original projects of many monuments. This issue is briefly discussed here by means of three examples taken from three completely different cultures and historical periods: the so-called “air shafts” of the Great Pyramid, the urban layout of the capital of the Incas, and the design of the Pantheon.

New abundances of planetary nebulae located towards the bulge of the Galaxy are derived based on observations made at LNA (Brazil). We present accurate abundances of the elements He, N, S, O, Ar, and Ne for 56 PNe located towards the galactic bulge. The data shows a good agreement with other results in the literature, in the sense that the distribution of the abundances is similar to those works. From the statistical analysis performed, we can suggest a bulge-disk interface at 2.2 kpc for the intermediate mass population, marking therefore the outer border of the bulge and inner border of the disk.

In the frame of Symposium 264 which concerns Solar and Stellar Variability we address the space solar missions devoted to the various aspects of solar activity. We describe them in three time categories: missions ready for launch, missions which will operate in the 2012-2015 time frame and ambitious missions to be launched after 2015. We focus on the contributions of these missions according to the following criteria: Understanding mechanisms of activity, Improving detection and characterisation, Working out some prediction. Major activity contributors and manifestations are addressed: Coronal Mass Ejections, Flares, Solar winds, Magnetism (including dynamo), Irradiance.

This review summarizes the important properties of active black holes (BHs) up to z ~ 2; their mass, accretion rate, and growth rate. At higher redshifts, such information is only available for small samples that do not represent the entire population of active galactic nuclei (AGNs). Black hole spin is still unknown; it is speculated to change with redshift, but with little experimental evidence. The available data sets also enable a direct comparison of BH accretion rates and host galaxy star-formation rates (SFRs). The ratio of the BH growth rate g(BH) and the bulge growth rate g(bulge), suggests that the two are proportional to each other. The local value of g(bulge)/g(BH) in low-luminosity AGNs is of order 100 and the corresponding ratio in high-luminosity, high-redshift AGNs is of order 10. This has important implications regarding the parallel evolution of active BHs and their hosts.

Thermohaline mixing has been recently identified as the dominating process that governs the photospheric composition of low-mass bright giant stars (Charbonnel & Zahn 2007a). Here we present the predictions of stellar models computed with the code STAREVOL that takes into account this mechanism together with rotational mixing and atomic diffusion. We compare our theorical predictions with recent observations and discuss how the corresponding yields for 3He are compatible with the observed behaviour of this light element in our Galaxy.

A method is suggested to explore the gravitational wave background (GWB) in the frequency range from 10−12 to 10−8 Hz. That method is based on the precise measurements of pulsars' rotational parameters: the influence of the gravitational waves (GW) in the range will affect them and therefore some conclusions about energy density of the GWB can be made using analysis of the derivatives of pulsars' rotational frequency. The calculated values of the second derivative from a number of pulsars limit the density of GWB Ωgw as follows: Ωgwh2 < 10−6. Also, the time series of the frequency ν of different pulsars in pulsar array can be cross-correlated pairwise in the same manner as in anomalous residuals analysis thus providing the possibility of GWB detection in ultra-low frequency range.

The Kepler mission will obtain high precision, continuous lightcurves for more than ~150,000 stars over the next four years. Prior to primary mission operations, ten days of commissioning data were obtained for the ~52,000 brightest targets in the Kepler field. While Kepler's main goal is the discovery of transiting low mass planets, it will also provide a rich dataset for studies of variable stars. These commissioning data give a first glimpse of the amazing diversity of stellar variability Kepler will observe. Here, we discuss the tools we are currently developing to quantify variability in the Kepler data, and show initial results on the distribution of target stars in these metrics. Ultimately these measures will be used both to characterize the data and to select active rotationally modulated stars for rotation period determination.

Obtaining accurate measurements of the initial mass function (IMF) is often considered to be the key to understanding star formation, and a universal IMF is often assumed to imply a universal star formation process. Here, we illustrate that different modes of star formation can result in the same IMF, and that, in order to truly understand star formation, a deeper understanding of the primordial binary population is necessary. Detailed knowledge on the binary fraction, mass ratio distribution, and other binary parameters, as a function of mass, is a requirement for recovering the star formation process from stellar population measurements.

We present results from statistical analysis of the largest quasar surveys currently in existence: the Sloan Digital Sky Survey (SDSS), the 2dF QSO Redshift Survey (2QZ), and the 2dF-SDSS LRG and QSO (2SLAQ) Survey. The quasar luminosity function shows highly significant (>99.9%) evidence of downsizing: the number density of faint quasars peaks at lower redshift than bright quasars. We measure the distribution of quasar broad-line widths as a function of luminosity, particularly focusing on the Mg ii λ2799 line. There is a clear trend, such that more luminous quasars show less scatter in line width than fainter quasars. However, the scatter in line width for any given luminosity (particularly in the brightest objects) is so small that it challenges our current understanding of virial black hole mass estimates.

Population III stars initiated the chemical enrichment of the Universe. Chemical evolution models seem to favour fast rotators among the very low-metallicity population. When a star rotates fast, it ejects significant quantities of He and its nucleosynthesic products are modified compared to the case without rotation. The value of ΔY/ΔO is explored from a theoretical point of view through stellar models of zero- or very low-metallicity.

This is a brief introduction to the ideas behind the art installation Siderea, Homage to Galileo that was created for, and exhibited at the IYA 2009 Opening Ceremony at UNESCO in Paris. The text narrates the attraction that astronomy exercises on the author, who studied Classics before becoming an artist and has always been fascinated by science.

Post-AGB (PAGB) stars are luminous objects of low and intermediate mass in a final and short stage of evolution in the transition between AGB stars and planetary nebulae (PNe). In this work we present a quantitative spectral analysis of some hot PAGBs based on high resolution spectra. The stellar parameters and chemical composition were obtained from the synthesis of non-LTE spectra.

Star clusters are found in all sorts of environments, and their formation and evolution is inextricably linked to the star-formation process. Their eventual destruction can result from a number of factors at different times, but the process can be investigated as a whole through the study of cluster age distributions. Observations of populous cluster samples reveal a distribution following a power law of index approximately −1. In this work, we use M33 as a test case to examine the age distribution of an archetypal cluster population and show that it is, in fact, the evolving shape of the mass detection limit that defines this trend. That is to say, any magnitude-limited sample will appear to follow a dN/dτ = τ−1 relation, while cutting the sample according to mass gives rise to a composite structure, perhaps implying a dependence of the cluster disruption process on mass. In the context of this framework, we examine different models of cluster disruption from both theoretical and observational perspectives.

New method of precise clocks comparison based on observation and registration of giant pulses of the millisecond pulsars is discussed. It was shown that expected accuracy of comparison is about 0.2–2 ns and depends on uncertainty of delay in the Earth ionosphere and troposphere.

The Parkes Pulsar Timing Array project is timing 20 millisecond pulsars with the aims of detecting gravitational waves, establishing a time scale based on pulsar periods and improving solar-system ephemerides.

Lithium represents a key element in cosmology, as it is one of the few nuclei synthesized during the Big Bang. The primordial abundance of 7Li allows us to impose constraints on the primordial nucleosynthesis and on the baryon density of the universe. However, 7Li is not only produced during the Big Bang but also during galactic evolution: measures of stellar Li in our Galaxy suggest an almost constant Li abundance (the so-called Spite plateau) at low metallicities and a subsequent increase in the disk stars, leading to a Li abundance in Population I stars higher by a factor of ten than in Population II stars. This means that there must exist several possible stellar sources of 7Li: asymptotic giant branch stars, supernovae, novae, red giant stars. 7Li is also partly produced in spallation processes while 6Li is entirely produced by such processes. All of these sources have been included in galactic chemical evolution models and constraints have been derived on the primordial 7Li and its evolution, as well on stellar models. I will review these models and their results and what we have learned about 7Li evolution. Some still open problems, such as the disagreement between the primordial 7Li abundance as derived by WMAP and as measured in Population II stars, and the uncertainties about the main sources of stellar 7Li will be discussed.

Over the last few years, the existence of mutual feedback effects between accreting supermassive black holes powering AGN and star formation in their host galaxies has become evident. This means that the formation and the evolution of AGN and galaxies should be considered as one and the same problem. As a consequence, the search for, and the characterization of the evolutionary and physical properties of AGN over a large redshift interval is a key topic of present research in the field of observational cosmology. Significant advances have been obtained in the last ten years thanks to the sizable number of XMM–Newton and Chandra surveys, complemented by multiwavelength follow-up programs. I will present some of the recent results and the ongoing efforts (mostly from the COSMOS and CDFS surveys) aimed at obtaining a complete census of accreting black holes in the universe, and a characterization of the properties of the host galaxies.

Astronomy and Art, two worlds seemingly opposite. One scientific and rigorous, the other perceived as light and whimsical. But if these two worlds were united? If art gave itself to the service of science? If fantasy became a playful pretext to transmit knowledge to young children? I recount here my experience, that of a meeting, and of an adventure. How and why an astronomy book for the very young emerged from the collaboration between a painter and an astronomer of the Observatory of Paris.

Sulfur abundances are derived for a sample of ten B MS star members of the Orion association. The analysis is based on LTE model atmospheres and non-LTE line formation theory by means of spectrum synthesis analysis of Sii and Siii lines. The abundance distribution obtained for the Orion targets is homogeneous within the errors in the analysis: A(S)=7.15±0.05. This abundance result is in agreement with the solar value and with results for the Orion nebula. The sulfur abundances for Orion combined with previous results for other OB-type stars produce a relatively shallow sulfur abundance gradient with a slope of −0.037±0.012 dex Kpc−1.