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.

In this paper we analyze soft and hard X-ray emission of the 2002 September 20 M1.8 GOES class solar flare observed by RHESSI and GOES satellites, where soft X-ray emission precedes the onset of the main bulk hard X-ray emission by ~5 min. This suggests that an additional heating mechanism may be at work at the early beginning of the flare. However RHESSI spectra indicate presence of the non-thermal electrons also before impulsive phase. So, we assumed that a dominant energy transport mechanism during rise phase of solar flares is electron beam-driven evaporation. We used non-thermal electron beams derived from RHESSI spectra as the heating source in a hydrodynamic model of the analyzed flare. We showed that energy delivered by non-thermal electron beams is sufficient to heat the flare loop to temperatures in which it emits soft X-ray closely following the GOES 1–8 Å light-curve.

We present photometry for the globular cluster NGC 6642 using the F606W and F814W filters with the ACS/WFC third-generation camera aboard the Hubble Space Telescope. The colour–magnitude diagram shows sources reaching ≈ 6 mag below the turnoff in mF606W. Theoretical isochrone fitting was performed and evolutionary parameters were obtained, including the metallicity [Fe/H] = −1.80 ± 0.2 dex and age, log(age/yr) = 10.14 ± 0.05. We confirm that NGC 6642 is located in the Galactic bulge, at a distance of d⊙ = 8.05±0.66 kpc and suffers from a reddening of E(B − V) = 0.46 ± 0.02 mag. These values are in general agreement with those of previous authors. Completeness-corrected luminosity and mass functions were obtained for different annuli centred on NGC 6642. Their spatial variation indicates the existence of mass segregation and depletion of low-mass stars. Most striking is the inverted shape of the mass function itself, with an increase in stellar numbers as a function of increasing mass. This has been observed previously in other globular clusters and is also the result of N-body simulations of stellar systems which have reached ≃90% of their lifetime and are subjected to strong tidal effects. We thus conclude that NGC 6642 is a very old, highly evolved globular cluster. Its current location close to perigalacticon, at only 1.4 kpc from the Galactic Centre, may contribute to this high level of dynamical evolution and stellar depletion.

The so-called solar cycle is generally characterized by the quasi-periodic oscillatory evolution of the photospheric spots number. This quasi-periodic pattern has always been an intriguing question. Several physical models were proposed to explain this evolution and many mathematical data analysis were employed to determine the principal frequencies noticeable in the measured data. Both approaches try to predict the future evolution of the solar activity and to understand the physical phenomena producing these cycles. Here we present the analysis of the sunspots number evolution using the time-delay approach. Our results show than the solar cycle can also be characterized by this behavior implying the influence of the past evolution over the present one, suggesting an histeresis mechanism, linked probably with magnetic activity.

The abundance derivation of heavy r-elements may provide a better understanding of the r-process, and the determination of several reference r-elements should allow a better determination of the star's age. The spatial ultraviolet (UV) region presents a large number of lines of heavy elements, and in some cases such as Bi, Pt, Au, detectable lines are only available in the UV. The extreme “r-process star” CS 31082-001 ([Fe/H] = −2.9) was observed in the spatial UV in order to determine abundances of the heavy elements, using STIS on board HST.

Ejection of material after the Deep Impact collision with Comet Tempel 1 was studied based on analysis of the images made by the Deep Impact cameras during the first 13 minutes after impact. Analysis of the images shows that there was a local maximum of the rate of ejection at time of ejection ~10 s with typical velocities ~100 m/s. At the same time, a considerable excessive ejection in a few directions began, the direction to the brightest pixel changed by ~50°, and there was a local increase of brightness of the brightest pixel. The ejection can be considered as a superposition of the normal ejection and the longer triggered outburst.

The near-UV NH3360 feature has been measured in a sample of 35 early-typegalaxies in a wide range of masses and environments. We found that, contrary towhat is seen with Mg- and C-sensitive Lick-style indices, NH3360 does not varysignificantly with galaxy velocity dispersion. When compared with solar-scaledstellar population models N/Fe appears mildly enhanced. We do not detect anydifference in the NH3360 index between galaxies in different environments. Weoutline the important implications of these conclusions for our understanding ofthe origin of carbon and nitrogen, and the star formation histories ofearly-type galaxies.

Globular clusters (GCs) are stellar systems (~106 M⊙) with very regular symmetry, single age, and single metallicity. Spectroscopic studies have revealed very old ages, suggesting that GCs were formed in the earliest stages of galaxy formation and assembly. The aim of this work is to find out how far we can measure the GC luminosity function, specific frequency, and radial distribution, applying the surface-brightness-fluctuations (SBF) technique to deep ACS images. To this end, we apply the effects caused by higher redshift to HST/ACS images (in two optical bands, F606W and F814W) of M87, an elliptical galaxy with a very well-studied GC system. The effects involved are: (i) evolution, (ii) inverse k correction, (iii) binning of the image to smaller angular size, (iv) cosmological dimming of surface brightness, and (v) noise addition to account for different exposure times. After processing the images we detect the brightest GCs through direct photometry (e.g., with SExtractor), whereas the unresolved clusters are measured through SBFs. The above treatment is repeated for z=0.05, 0.1, 0.14, and 0.18, and the results are compared to the measurements at z=0 to estimate biases and incompleteness.

We present the distribution of Galactic bulge globular clusters and a method based on simultaneous detection of field and cluster horizontal branches to derive the cluster distances. This method has the advantage of being independent of both reddening and the reddening law, RV = AV/E(B−V). The vast majority of clusters projected in the direction of the Galactic bulge are located on the near side of the Galactic Center. Deviations from the reddening law do not seem to be responsible for this peculiarity. We need to introduce a peculiar, steep dependence of the absolute horizontal-branch magnitude with metallicity in the metal-rich regime if we want to reproduce a symmetrical distribution. Instead, if the observed distribution is correct, we expect a rather large number of bulge globular clusters are still to be discovered.

Accretion disk outflows are an important part of the quasar phenomenon. They might play a major role in distributing metals to the galactic surroundings, halting growth of the central black hole and providing kinetic energy “feedback” to regulate star formation in the host galaxies. Some models of galaxy evolution indicate that feedback requires kinetic energy luminosities, LK, that are ~5% of the quasar bolometric; LK/L = Ṁwν2/2η:Ṁaccc2 ~ 5% is possible if Ṁw ~ Ṁacc (with ν~ 0.1c, and η ~ 0.1). Here we describe results from two studies designed to test the theoretical energetics of radiatively driven outflows and derive observational constraints on the outflow geometry and physical properties emphasizing weaker outflow features like NALs and mini-BALs.

Young, massive stars influence their ambient medium through winds and radiation. The outcome of this feedback depends on the number of massive stars in a star cluster and on the density of the ambient medium. This contribution is based on a comparison of observations to the results of numerical simulations. We discuss the gravitational fragmentation of feedback-driven shells expanding from young stellar clusters. The thin-shell approximation is compared to 3D hydrodynamical simulations with smoothed-particle hydrodynamics and adaptive-mesh refinement codes. We explore the influence of external pressure and propose a thick-shell dispersion relation, where the pressure of the external medium is included. The mass spectrum of the shell fragments is constructed and we speculate about the origin of the deficit of low-mass objects.

In the last few years, X-ray observational studies of young star clusters have advanced significantly, mainly thanks to the great capabilities of current X-ray observatories such as Chandra and XMM/Newton. In addition to enabling a detailed study of coronae of individual bright stars, high-spatial-resolution X-ray observations of many young clusters and star-forming regions, even massive and distant ones, have led to the detection of large populations of X-ray-bright members, often down to subsolar masses, and despite strong absorption. The peculiar ability of X-ray emission to select young, low-mass cluster stars against a crowded Galactic-plane field-star background has permitted better studies of global cluster properties, with respect to optical/infrared studies alone, including of cluster initial mass functions (across wide mass ranges), star-formation histories (with indication of age spreads—or even sequences—in many clusters) and morphologies (various degrees of symmetry and dynamical relaxation), sometimes with evidence of mass segregation. Also, the complementary availability of X-ray and optical/infrared data has enabled to place constraints on lifetimes and depletion mechanisms of pre-main-sequence circumstellar disks.

We compare nuclear globular clusters (nGCs) in dwarf galaxies and Galactic GCs with extended (hot) horizontal branches (EHB–GCs) to test the suggested external origin of the latter and the conditions under which GC self-enrichment can operate. We show that the present-day escape velocity (vesc) of stellar ejecta to reach the cluster tidal radius compares with those of EHB–GCs. For EHB–GCs, we find a correlation between the present-day vesc and their metallicity as well as (V − I) colour. The similar vesc and (V − I) distribution of nGCs and EHB–GCs implies that nGCs could also have complex stellar populations. The vesc–[Fe/H] relation could reflect the known relation of increasing stellar-wind velocity with metallicity, which in turn explains why more metal-poor clusters typically show more peculiarities in their stellar population than more metal-rich clusters of the same mass.

Velocity-dependent flux ratios of the broad Lyα, Civ, Hβ, and Hα lines are used to investigate conditions in the archetypical displaced BLR peak emitter 3C 390.3. Our results suggest that gas producing the the UV emission lines has a lower density than the higher-velocity gas producing broad disk-like profile and is less flattened.

We simulate the chemical processes in the three evolution periods of the solar nebula, which are (i) the quasi-stationary prestellar cloud core, (ii) the gravitationally collapsing protostellar core, and (iii) the evolving gas-dust disk. Our purpose is to identify chemical parameters which reflect special aspects of the interactions between the gas and ice phase in the different periods, e.g. isotopic or molecular ratios. In this study we derive the D/H and 15N/14N ratio of selected compounds as well as the CO2/H2O ratio to measure the fraction of non-polar to polar ice in the grain mantles. The chosen ratios depend on the depletion-enrichment relation between the ice and gas phases driven by the thermal evolution in each period, especially during the collapse. Hence, we have made great efforts in order to derive realistic and compact hydrodynamic models to describe the evolutionary periods of the solar nebula.

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.

We present BV photometry and the results of a search for stellar variability in the globular cluster NGC 5286, which has tentatively been associated with the Canis Major dwarf spheroidal galaxy. Our results indicate an Oosterhoff type II for the cluster, which is unusual for an object of extragalactic origin.

This paper provides an introduction to IAU Symposium 266 on star clusters as basic building blocks in space and time. We define clusters as bound systems and discriminate them from general stellar clusterings or groups and unbound associations. We give a few examples of young, embedded, compact clusters which may evolve into looser, open clusters after dynamical relaxation due to mass loss and secular relaxation processes. We ask how and where star clusters form (in normal and interacting galaxies) and provide statistics of open clusters in terms of cluster masses and ages in the solar neighborhood (where observational data are most complete). Finally, we list a number of basic questions for current and future star cluster research and discuss the prospects for cluster studies with the next generation infrared and submillimeter telescopes (Herschel; JWST, E–ELT; ALMA, NOEMA).

We obtained CCD observations of the open cluster NGC 752 with the 1.8m Vatican Advanced Technology Telescope (Mt. Graham, Arizona) with a 4K CCD camera and eight intermediate-band filters of the Stromvil (Strömgren + Vilnius) system. Four 12′ × 12′ fields were observed, covering the central part of the cluster. The good-quality multicolor data made it possible to obtain precise estimates of distance moduli, metallicity and foreground reddening for individual stars down to the limiting magnitude, V = 17.5, enabling photometric identification of faint cluster members. The new observations provide an extension of the lower main sequence to three magnitudes beyond the previous (photographic) limit. A relatively small number of photometric members identified at fainter magnitudes seems to be indicative of actual dissolution of the cluster from the low-mass end.

We present a new catalog of isolated galaxies (coined as UNAM–KIAS) obtained through an automated systematic search. The 1520 isolated galaxies were found in ~ 1.4 steradians of the sky in the Sloan Digital Sky Survey Data Release 5 (SDSS DR5) photometry. The selection algorithm was implemented from a variation of the criteria developed by Karachentseva (1973), with full redshift information. This new catalog is aimed to carry out comparative studies of environmental effects and constraining the currently competing scenarios of galaxy formation and evolution.