We present abundance measurements in the tidally disrupted globular cluster NGC 6712. In this cluster, there are large star-to-star variations of the light elements C, N, O, F and Na. While such abundance variations are seen in every well-studied globular cluster, they are not found in field stars and indicate that clusters like NGC 6712 cannot provide many field stars and/or field stars do not form in environments with chemical-enrichment histories like those of NGC 6712. Preliminary analysis of NGC 5466, another tidally disrupted cluster, suggests little (if any) abundance variation for O and Na and the abundance ratios [X/Fe] are comparable to field stars at the same metallicity. Therefore, globular clusters like NGC 5466 may have been Galactic building blocks.

The Herschel Space Observatory is ESA's fourth Cornerstone mission and will be the largest, most sensitive telescope ever put into space. It will be the first space observatory to observe from the far-infrared to the submillimetre waveband, unveiling the cool, hidden universe for the first time. Herschel will observe stars and galaxies at the stage of formation and discover where all the cosmic dust polluting galaxies comes from. Given the huge public interest in large space missions such as Hubble and Spitzer, Herschel is an ideal opportunity to excite and inform the UK public during the International Year of Astronomy 2009. Here we present some of the education and outreach projects created by the Herschel Outreach Group (HOG).

Early-type galaxies (ETGs) satisfy a now classic scaling relation Re ∝ σ1.2eI−0.8e, the Fundamental Plane (FP; Djorgovski & Davis 1987; Dressler et al. 1987), between their size, stellar velocity dispersion and mean surface brightness. A significant effort has been devoted in the past twenty years to try to understand why the coefficients of the relation are not the ones predicted by the virial theorem Re ∝ σ2eI−1e.

We focus on a comparison of the space densities of FR I and FR II extended radio sources at different epochs, and find that FR I and FR II sources show similar space density enhancements in various redshift ranges, possibly implying a common evolution.

The reflectance of Saturn's moon Enceladus has been measured at far ultraviolet (FUV) wavelengths (115–190 nm) by Cassini's UltraViolet Imaging Spectrograph (UVIS). At visible and near infrared (VNIR) wavelengths Enceladus' reflectance spectrum is very bright, consistent with a surface composed primarily of H2O ice. At FUV wavelengths, however, Enceladus is surprisingly dark – darker than would be expected for pure water ice. We find that the low FUV reflectance of Enceladus can be explained by the presence of a small amount of NH3 and a small amount of a tholin in addition to H2O ice on the surface.

We describe the methodology required for estimation of photometric estimates of metallicity based on the SDSS gri passbands, which can be used to probe the properties of main-sequence stars beyond ~10 kpc, complementing studies of nearby stars from more metallicity-sensitive color indices that involve the u passband. As a first application of this approach, we determine photometric metal abundance estimates for individual main-sequence stars in the Virgo Overdensity, which covers almost 1000 deg2 on the sky, based on a calibration of the metallicity sensitivity of stellar isochrones in the gri filter passbands using field stars with well-determined spectroscopic metal abundances. Despite the low precision of the method for individual stars, internal errors of σ[Fe/H]~0.1 dex can be achieved for bulk stellar populations. The global metal abundance of the Virgo Overdensity determined in this way is 〈[Fe/H]〉 = −2.0±0.1 (internal) ±0.5 (systematic), from photometric measurements of 0.7 million stars with heliocentric distances from ~10 kpc to ~20 kpc. A preliminary metallicity map, based on results for 2.9 million stars in the northern SDSS DR-7 footprint, exhibits a shift to lower metallicities as one proceeds from the inner- to the outer-halo population, consistent with recent interpretation of the kinematics of local samples of stars with spectroscopically available metallicity estimates and full space motions.

TS01 is an exceptional planetary nebula (PN) in the Galactic halo: it is the most oxygen-poor and has a double-degenerate core with mass close to 1.4M⊙, possibly a Supernova Ia progenitor. With data from the far UV to the IR we can pin down the abundances of half a dozen of elements. The oxygen abundance is by 1.9(±0.3) dex lower than in the Sun. Standard AGB models with appropriate mass and metallicity cannot explain the observed chemical composition. We find that additional mixing, induced by stellar rotation and/or by the presence of the close companion can explain most of the features of the abundance pattern in TS01.

Peculiar solar active regions (ARs), such as δ-islands and other high tilt bipoles, are commonly associated with the emergence of severely deformed magnetic flux tubes. Therefore, the study of these ARs provides valuable information on the origin and evolution of magnetic structures in the solar interior. Here, we infer the magnetic helicity properties of the flux tubes associated to a set of peculiar ARs by studying the evolution of photospheric magnetograms (SOHO/MDI) and coronal observations (SOHO/EIT and TRACE) in combination with force-free models of the magnetic field. We discuss how our results relate to different models of the evolution of emerging magnetic flux tubes.

The helium produced by AGB and super-AGB stars is a key quantity to understand whether these objects may have been the main polluters of the interstellar medium within globular clusters, and originate a second generation of stars with a chemistry showing the imprinting of their ejecta. Helium is the most important element for this topic, as any difference in the original helium between the two populations would determine clearly distinguishable features both in the morphology of the Horizontal Branches and in the Main Sequences. We present the helium yields from massive AGB stars, and show that the results are rather robust, being approximately independent of the various uncertainties that affect the description of the evolution of these stars. The implications for the self-enrichment scenario are discussed and commented.

High-precision radial-velocity techniques, which enabled the detection of extra-solar planets, are now sensitive to the lowest-order relativistic effects in the data of spectroscopic binary stars (SBs). We show how these effects can be used to derive the absolute masses of the components of eclipsing single-lined SBs and double-lined SBs from Doppler measurements alone. High-precision stellar spectroscopy can thus substantially increase the number of measured stellar masses, thereby improving the mass-radius and mass-luminosity calibrations.

One of the more popular theories to account for the abundance anomalies in globular cluster stars is the ‘self-pollution scenario,’ where the polluters were a previous generation of intermediate-mass asymptotic giant branch (AGB) stars. This idea has proved attractive because: (i) the hot-bottom burning experienced by these objects qualitatively provides an ideal proton-capture environment to produce helium and convert C and O to N, Ne to Na and Mg to Al, and (ii) the slow winds from these stars allow their retention by the cluster's gravitational potential. New stellar yields from low-metallicity AGB models are presented and compared to abundances derived in globular clusters. We also discuss external pollution and inhomogeneous-pollution models that use AGB stars as polluters. Current models of AGB stars cannot match all observational features of globular cluster stars. However, stellar modelling uncertainties are considerable and suggest AGB stars should not be ruled out just yet.

Focusing on primitive icy minor bodies in the solar system like cometary nuclei, centaurs, transneptunian objects (TNOs), and main-belt comets (MBCs) we investigate the stability of these objects against rotational breakup by comparing their location in (radius – rotational period) space with respect to separation lines of the stable and breakup zones in this plane. We estimate the bulk tensile strength according to new structural and elasto-mechanical models of grain-aggregates, using these tensile strengths to compute separation lines. We note that the process of grain coagulation and growth is highly uncertain in the field of solar system formation and we simply don't know how to grow interstellar grains to aggregates larger than about 1 mm but we apply in our calculations the recently available elasto-mechanical models of grain-aggregates. Accorging to this study most of the observed comets, centaurs, TNOs, and MBCs are stable against rotational breakup, with a few notable exceptions. E.g., we suggest that the rotational fission is a likely scenario for the Haumea-family in the Kuiper belt.

We discuss three effects of axial rotation at low metallicity. The first one is the mixing of the chemical species which is predicted to be more efficient in low metallicity environments. A consequence is the production of important quantities of primary 14N, 13C, 22Ne and a strong impact on the nucleosynthesis of the s-process elements. The second effect is a consequence of the first. Strong mixing makes possible the apparition at the surface of important quantities of CNO elements. This increases the opacity of the outer layers and may trigger important mass loss by line driven winds. The third effect is the fact that, during the main-sequence phase, stars, at very low metallicity, reach more easily than their more metal rich counterparts, the critical velocity. We discuss the respective importance of these three effects as a function of the metallicity. We show the consequences for the early chemical evolution of the galactic halo and for explaining the CEMP stars. We conclude that rotation is probably a key feature which contributes in an important way to shape the evolution of the first stellar generations in the Universe.

Camille Flammarion's observatory, located in Juvisy-sur-Orge in the suburbs of Paris, has been idle since 1962. Property of the Société Astronomique de France (SAF), it was made available to the city of Juvisy-sur-Orge since 1971, and contains a unique collection of objects and books currently being sorted out. The observatory is being restored by the SAF, thanks to the support of the city of Juvisy-sur-Orge, the French Académie des Sciences and the “Amis de Camille Flammarion” association. In 2006, the Maxime Goury Laffont foundation funded the refurbishment of the 240 mm refractor and in 2007 funds were obtained to restore the dome and central building. The main aim of the project is to make this historical place a popular observatory dedicated to astronomy and the sciences which Camille Flammarion enjoyed and contributed to. It constitutes a unique example in France of synergies linking associations, municipality, regional- and national-level institutions.

The first discussion session held at the IAU Symposium 268 focussed on the deuterium content in the local interstellar medium (LISM) and in high-redshift systems. There were two key questions proposed to the audience: 1) what should be taken as representative abundance of D in the LISM, and 2) how can we explain the dispersion of the D abundance measured in high-redshift, very low metallicity environments? While on the latter point people seem to agree that observational and data analyses uncertainties are the most likely explanation, on the former question no consensus was reached. The historical and observational background at the basis of these questions and the discussion are schematically reported here.

We provide observational constraints on disk galaxy evolution for a sample of 28 local edge-on early-type (S0–Sb) disk galaxies. We do this in two ways: (i) we use simple dynamical modelling techniques to constrain their stellar and dark matter content (Williams et al. 2009) and (ii) we compare the zero points of the Tully-Fisher relations (TFRs; Tully & Fisher 1977) of the spirals and S0s.

We have identified ~500 relatively relaxed galaxy clusters at low redshift (z < 0.3) from the maxBCG catalog with double radio lobes at the center; about 200 radio counterparts of brightest cluster galaxies (BCGs) of these clusters appear to be wide-angle tailed (WAT) radio sources, indicating ongoing interaction between its host galaxy and the surrounding ICM. Our analysis suggests that the radio power of WAT is positively correlated with the optical luminosities of host BCGs, and increases with redshift; whereas the cluster ellipticity-radio galaxy fraction relation shows no obvious difference between WAT and non-WAT clusters.

The methods of automatic solar active phenomenon or event detection have been researched and explored by people for many years, which have gone into actual services. The paper analyzes the relationship between these methods of automatic detection and the forecast or alert, using the solar short-term proton events predictions as an example. Using automatic method to conduct forecast or alert is under thinking.

We have completed a spectroscopic study of the “12.4 hr clump”, the second largest substructure in the Quasar Equatorial Survey Team (QUEST) catalog. First discovered as an over-density of RR Lyrae stars (Vivas et al. 2001, ApJL 554 33), the region containing the “12.4 hr clump” has generated much interest (Newberg et al. (2002), Martinez-Delgado et al. (2007), Juric et al. (2008), amongst many others). Our first spectroscopic study of this clump revealed the presence of a sharp peak in the radial velocity histogram for the candidate stars (Duffau et al. 2006). The combination of this result and metal abundance estimates for the sample was then interpreted as a signature of the presence of a stellar stream within the clump. This sub-structure was named the “Virgo Stellar Stream” (VSS), given its location in the direction of the Virgo Constellation, at approximately 20 kpc from the Sun. Several other groups have studied this region and have suggested that the over-density containing the VSS could extend to larger areas of the sky (outside QUEST's observing range). We present the complete spectroscopic follow up of the clump candidates present in QUEST and the composite of the studies we performed along the same l.o.s., including data at brighter magnitudes (Vivas et al. 2008). Our study confirmed the nature of the VSS, revealed its likely extent within the QUEST survey and defined a number of its relevant properties.

Einstein-Aether gravity theory has been proven successful in passing experiments of different scales. Especially its Eddington parameters β and γ have the same numerical values as those in general relativity. Recently Xie and Huang (2008) have advanced this theory to a second post-Newtonian approximation for an N-body model and obtained an explicit metric when the bodies are point-like masses. This research considers light propagation in the above gravitational field, and explores the light deflection, time delay, frequency shift etc. The results will provide for future experiments in testing gravity theories.