We have obtained high-resolution VLT/FLAMES spectra of a number of giants in the LMC cluster Hodge 11 and the surrounding field. We present results of a detailed model-atmosphere abundance analysis for a variety of elements, including Fe, Ca, Ti, Si, Sc, Ni and Cr.

The properties of the binary components of the eclipsing variables found in the 47 Tuc core region as part of a search for extrasolar planets have been re-examined following reanalysis of the image photometry and calibration. This is part of an ongoing study to find fundamental properties of stars of different metallicity in a variety of environments through eclipsing-binary analyses.

In no other epoch of Western history like in the Middle Ages, cosmology was so key an element of culture and, one way or another, the motion of the heavens ended up impregnating the literature of that time. Among the most noteworthy poets we find Dante Alighieri, who became famous for his Commedia, a monumental poem written roughly between 1307 and his death in 1321, and which the critics from 16th century onwards dubbed Divina. In this and other works, Dante pictures the cosmic image for the world, summing up the current trends of Neoplatonic and Islamic traditions. The Barolo Palace in the city of Buenos Aires is a singular combination of both astronomy and the worldview displayed in Dante's poetic masterpiece. Some links of the Palace's main architectural structure with the three realms of the Comedy have been studied in the past. In this note we consider its unique astronomical flavor, an issue which has not been sufficiently emphasized yet.

In the framework of he ESO Large Program “First Stars”, high resolution (R=45000) high S/N ratio spectra have been obtained for a sample of Extremely Metal Poor Stars (EMP stars), 35 giants and 18 turnoff stars. Among them 37 have a very low metallicity: [Fe/H]< −2.9.

We performed high-resolution three dimensional numerical simulations of relativistic MHD jets carrying an initially toroidal magnetic field responsible for the process of jet acceleration and collimation. We find that in the 3D case the toroidal field gives rise to strong current driven kink instabilities leading to jet wiggling. However, it appears to be able to maintain an highly relativistic spine along its full length.

We have obtained [Mg/Fe] for around 77% of the stars of the MILES library of stellar spectra in order to include this important information into simple stellar population (SSP) models. The abundance ratios, which were carefully calibrated to a single uniform scale, were obtained through a compilation from high spectral resolution works plus robust spectroscopic analysis at medium resolution. The high resolution data provided an extensive control sample. Average uncertainties (0.06 and 0.12 dex for the high and medium resolution samples respectively) and the good coverage of the stars with [Mg/Fe] over the MILES's parameter space will permit us to semi-empirically build up new SSP models with accurate α-enhancements for ages older than 1 Gyr. This will open new prospects for evolutionary stellar population synthesis.

We present the results of a cross-correlation analysis of the projected positions of AGNs and galaxies at redshifts from 0.3 to 3.0. It is widely accepted that the origin of AGN activity is accretion of matter onto a massive black hole at the center of a galaxy (e.g., Lynden-Bell 1969). To explain the activity of AGNs, a large fraction of matter in the galaxy must be delivered to the inner region on a short timescale (Hopkins et al. 2008). One possible mechanism for causing rapid gas inflows into the central region is a major galaxy merger between gas-rich galaxies (e.g., Kauffmann & Haehnelt 2000). If this is the case, AGNs are expected to be found in an environment with higher galaxy density than that of typical galaxies. We investigated environments of ~ 750 AGNs, which is about a ten times larger sample than used in previous studies, and we find a significant excess of galaxies around the AGNs in the redshift range of 0.3 to 1.8. We used the Japanese Virtual Observatory (JVO) to obtain the Subaru Suprime-Cam images and UKIDSS data around known AGNs. The datasets accessed through the JVO are: Catalog of Quasars and Active Galactic Nuclei by Veron-Cetty et al. (2006), SDSS DR-5 Quasar Catalog by Schneider et al. (2007), Subaru Suprime-Cam Reduced Image Archive of JVO, and UKIDSS DR2 catalog by Warren et al. (2007). We divided all the AGN samples into four redshift groups, 0.3≲z ≲ 0.8, 0.8≲ z ≲ 1.5, 1.5≲ z ≲ 1.8, and 1.8≲ z ≲ 3.0. For each redshift group, the dataset was further divided into a fainter group (MV ≥ −25 mag) and a brighter group (MV < −25 mag). We found that the correlation length of the high-redshift bright sample (1.5≲ z ≲ 1.8) was larger than that of the low-redshift faint sample (0.3≲ z ≲ 0.8). We also found that the correlation length was larger for the faint group at redshift range 0.8≲ z ≲1.5. These results can be explained by downsizing of mass assembly. More details can be found in the paper by Shirasaki et al. (2009). Our result implies that the Japanese Virtual Observatory can be a powerful tool to investigate the co-evolution of central black holes and galaxies at the intermediate redshift universe.

The World at Night (TWAN) is a global program to produce, collect, and present stunning photographs and time-lapse videos of the world's most beautiful and historic sites against the night-time backdrop of stars, planets, and celestial events. TWAN is a bridge between art, science and humanity to bring the message of peace, concealed in the sky. Organised by “Astronomers Without Borders”, the project consist of world's best night sky photographers in over countries and coordinators, regional event organisers, and consultants. TWAN was also designated as a Special Project of the International Year of Astronomy 2009. While the project's global exhibitions and educational events peaked during IYA2009, TWAN is planned for long term in several phases and will continue to create and exhibit images in the next years.

We analyze a sample of 21 super-metal-rich (SMR) stars, using high-resolution échelle spectra obtained with the Fiber-fed Extended Range Optical Spectrograph at the 1.5m ESO telescope. The metallicities are in the range 0.07 ≤ [Fe/H] ≤ 0.45, 3 of them in common with Pompéia et al. (2009). Geneva photometry, astrometric data from Hipparcos, and radial velocities from CORAVEL are available for these stars. The peculiar kinematics suggests the thin disk close to the bulge as the probable birthplace of these stars (Grenon 1999). From Hipparcos data, it appears that the turnoff of this population indicates an age of 10-11 Gyr (Grenon 1999). Detailed analysis of the sample stars is carried out, and atmospheric parameters are derived from spectroscopic and photometric determinations. Oxygen abundances of these stars are derived, and [O/Fe] overabundances up to +0.35 are found.

We present a new technique to analyze color–magnitude diagrams, such as those of stellar clusters, based on the cross-entropy global-optimization procedure. The method uses theoretical isochrones available in the literature and minimizes an objective function that describes the quality of a fit to the color–color and color–magnitude diagrams. The objective function is based on the two-dimensional distances of the points in the color–magnitude and color–color diagrams to the theoretical curves and is modified by weights that take into account the stellar distance to the observed cluster center, observed magnitude uncertainties and the King profile of the cluster, among others. The parameters determined simultaneously are distance, reddening, age and metalicity. The method uses a Monte Carlo approach to obtain uncertainties on the determined parameters for the cluster. We present results for 10 well-studied open clusters and show that the results are consistent with previous studies.

The Sloan Digital Sky Survey has made it possible to identify the first samples of active galaxies with estimated black hole masses below ~ 106M⊙. We have obtained Spitzer IRS low-resolution spectra, covering 5–38 μm, of a sample of 41 Seyfert galaxies with low-mass black holes. Our sample includes SDSS-selected objects from the low-mass Seyfert 1 sample of Greene & Ho (2004) and the low-mass Seyfert 2 sample of Barth et al. (2008), as well as NGC 4395 and POX 52. The goals of this work are to examine the dust emission properties of these objects and investigate the relationship between type 1 and type 2 AGNs at low luminosities and low masses, to search for evidence of star formation, and to use emission-line diagnostics to constrain physical conditions within the narrow-line regions. Here we present preliminary results from this project.

In this paper we discuss the fact that the observed “accelerations” (i. e., higher velocities at larger distances from the source) observed along some Herbig-Haro (HH) jets directly imply that the ejection velocity has to be time-dependent. Even though discussed in the early literature of the subject, this is an often forgotten fact.

The star formation and the subsequent metallic enrichment of spiral galaxies, occurring at the early phases of their evolution, produce emission lines whose contribution may change the colors of these objects. We have computed this contribution with consistent chemo-spectro-photometrical theoretical models in order to calculate the variations in the colors evolution.

We present the strong links between music and astronomy over 25 centuries.

Our research addresses the observed evolution of MBH and L/LEdd of type 1 radio-quiet AGNs. Measurements of MBH and L/LEdd in a sample of sources at z<0.75 using the “Hβ method” (Netzer & Trakkhtenbrot 2007) as well as new measurements of these properties at 0.75<z<2 using the “Mg ii λ2798 method”) show significant evolution of L/LEdd for any value of MBH up to z = 2 (see Figure 1). In a dedicated near-IR project we obtained the most reliable sample of MBH and L/LEdd estimates for z ~ 2.3 and z ~ 3.4 AGN (Netzer et al. 2007; Shemmer et al. 2004); the distribution of L/LEdd is very broad (Figure 1) and ~ 1/2 of the sources have L/LEdd<0.2, implying tgrowth>tuniverse and hence an earlier epoch of fast growth. Our on-going Gemini–VLT campaign focuses on z ~ 4.8 sources, with the Mg ii line observed in the H-band (Figure 2). The analysis of ~ 1/3 of the spectra uncovers, again, a broad distribution of L/LEdd, with several sources having L/LEdd ≫ 1, suggesting an early episode of fast BH growth.

The growth of a forming star takes place by accretion from the surrounding dense medium, facilitated by a circumstellar disk. But at the same time the forming system produces collimated outflows of gas that remove excess angular momentum and magnetic flux. A key question in the field is whether we can extend the disk/jet model to stars of the largest masses or if other ingredients are present. In this note, I review recent observations from the Very Large Array and the Submillimeter Array, of IRAS 16547-4247, a massive young stellar object that exhibits evidence for both a disk and an outflow.

We present extensive photometric and spectroscopic study to give a new insight in the bulge stellar population. Super-solar α/Fe and its constant value along the radial profile, in most of the galaxies, suggest that the star formation in these objects has been fast and occurred at the same time in the whole bulge.

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.

The WEBDA database of open clusters (hereafter OCs) in the Galaxy contains 970 OCs, of which 911 have age determinations, 920 have distance measurements, and 911 have color-excess data. Base on the statistical analysis of global properties of open clusters, we investigate disk properties such as the height above the Galactic plane. We find that old open clusters (age ≥ 1 Gyr) are preferentially located far from the Galactic plane with 〈|z|〉~394.5 pc. They lie in the outer part of the Galactic disk. The young open clusters are distributed in the Galactic plane almost symmetrically with respect to the Sun, with a scale height perpendicular to the Galactic plane of 50.5 pc. The age distribution of open clusters can be fit approximately with a two-component exponential decay function: one component has an age scale factor of 225.2 Myr, and the other consists of longer-lived clusters with an age scale of 1.8 Gyr, which are smaller than those derived by Janes & Phelps (1994) of 200 Myr and 4 Gyr for the young and old OCs, respectively. As a consequence of completeness effects, the observed radial distribution of OCs with respect to Galactocentric distance does not follow the expected exponential profile. Instead, it falls off both for regions external to the solar circle and more sharply towards the Galactic Center, which is probably due to giant molecular cloud disruption in the center. We simulate the effects of completeness, assuming that the observed distribution of the number of OCs with a given number of stars above the background is representative of the intrinsic distribution of OCs throughout the Galaxy. Two simulation models are considered, in which the intrinsic number of the observable stars are distributed (i) assuming the actual positions of the OCs in the sample, and (ii) random selection of OC positions. As a result, we derive completeness-corrected radial distributions which agree with an exponential disk throughout the observed Galactocentric distance in the range of 5–15 kpc, with scale lengths in the range of 1.6–2.8 kpc.

The study of stellar populations in early-type galaxies give us clues on how they form and evolve. We calculate age, [Z/H], and [α/Fe] ratio for 162 early-type galaxies using the SSP models from Thomas, Maraston, & Bender (2003) applied to Lick indices measurements, such as Hβ, Mgb, Fe5270 and Fe5335. Those were obtained from longslit spectra observed in the ESO 1.52m telescope as described in Ogando et al. (2008). We study the relations between the SSP parameters and velocity dispersion, as well as the influence of environment on these relations. We find that age, [Z/H], and [α/Fe] correlate well with velocity dispersion, so that more massive galaxies, have on average, higher metallicities, ages and abundance ratios than that of the low-mass ones. Galaxies in high density regions are older and more metal-rich than those in regions with low number of neighbors. These results are not consistent with standard predictions of hierarchical clustering. In the last decade, this “anti-hierarchical” behavior has also been generally tagged as downsizing and has challenged the current theoretical framework of galaxy formation, calling for new ways of star formation regulation in early-type galaxies.