Search

Osteoarthritis‐related changes in joint space measurements over time are small and sensitive to measurement error. The Reliable Change Index (RCI) determines whether the magnitude of change observed in an individual can be attributed to true change. This study aimed to examine the RCIas a novel approach to estimating osteoarthritis progression. Data were from 167 men and 392 women with knee osteoarthritis (diagnosed using the American College of Rheumatology criteria) randomized to the placebo arm of the 3‐year Strontium Ranelate Efficacy in Knee Osteoarthritis trial (SEKOIA) and assessed annually. The RCIwas used to determine whether the magnitude of change in joint space width (JSW) on radiographs between study years was likely to be true or due to measurement error. Between consecutive years, 57–69% of participants had an apparent decrease (change <0) in JSW, while 31–43% of participants had annual changes indicating improvement in JSW. The RCIidentified JSWdecreases in only 6.0% of patients between baseline and year 1, and in 4.5% of patients between the remaining study years. The apparent increases in JSWwere almost eliminated between baseline and year 1, and between years 1 and 2 only 1.3% of patients had a significant increase, dropping to 0.9% between years 2 and 3. The RCIprovides a method to identify change in JSW, removing many apparent changes that are likely to be due to measurement error. This method appears to be useful for assessing change in JSWfrom radiographs in clinical and research settings.

Context. NGC 6522 has been the first metal-poor globular cluster identified in the bulge by Baade. Despite its importance, very few high-resolution abundance analyses of stars in this cluster are available. The bulge metal-poor clusters may be important tracers of the early chemical enrichment of the Galaxy.

We present abundances of Fe, Na, and O for 1409 red giant stars in 15 galactic globular clusters (GCs), derived from the homogeneous analysis of high-resolution FLAMES/GIRAFFE spectra. Combining the present data with results from our FLAMES/UVES spectra and from previous studies within the project, we obtained a total sample of 1958 stars in 19 clusters, the largest and most homogeneous database of this kind to date. The programme clusters cover a range in metallicity from [Fe/H] $= -2.4$dex to [Fe/H] $= -0.4$dex, with a wide variety of global parameters (morphology of the horizontal branch, mass, concentration, etc.). For all clusters we find the Na-O anticorrelation, the classical signature of the operation of proton-capture reactions in H-burning at high temperature in a previous generation of more massive stars that are now extinct. Using quantitative criteria (from the morphology and extension of the Na-O anticorrelation), we can define three different components of the stellar population in GCs. We separate a primordial component (P) of first-generation stars, and two components of second-generation stars, that we name intermediate (I) and extreme (E) populations from their different chemical composition. The P component is present in all clusters, and its fraction is almost constant at about one third. The I component represents the bulk of the cluster population. On the other hand, E component is not present in all clusters, and it is more conspicuous in some (but not in all) of the most massive clusters. We discuss the fractions and spatial distributions of these components in our sample and in two additional clusters (M 3 = NGC 5272 and M 13 = NGC6205) with large sets of stars analysed in the literature. We also find that the slope of the anti-correlation (defined by the minimum O and maximum Na abundances) changes from cluster-to-cluster, a change that is represented well by a bilinear relation on cluster metallicity and luminosity. This second dependence suggests a correlation between average mass of polluters and cluster mass.

Aims. We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes b= -4°, b= -6°, and b= -12°. A fourth field including NGC 6553 is also included in the discussion.

Context. It is known that the Canary Islands are normally affected by dominant winds flowing from north-northeast, that in some meteorological conditions, can transport sand from the Sahara desert at high altitude. The dust may affect the efficiency of the telescopes and decrease the transparency of the sky.

Context.The Galactic globular cluster 47 Tucanae is central to studies of Galaxy formation, and a test-bed for theoretical models, distance determination and extragalactic age-dating techniques. Independent parallax-based distance determinations in the optical spectral range provide discrepant results; also, star counts along the Red Giant Branch from optical data have disclosed a worrying disagreement with theoretical predictions, that impacts not only the theory of red giant stars, but also the calibration of the age scale of extragalactic systems.

Context.Young massive clusters are usually deeply embedded in dust and gas. They represent excellent astrophysical laboratories for the study of massive stars. Clusters with Wolf-Rayet (WR) stars are of special importance, since this enables us to study a coeval WR population at a uniform metallicity and known age.

Aims.We investigate the nature of the recently catalogued star cluster candidate FSR 584, which is projected in the direction of the molecular cloud W 3 and may be the nearest globular cluster to the Sun.

Context.A large number of pulsars and X-rays sources are detected in globular clusters. To understand the structure and content of these clusters, accurate distances are required.

Aims.We present a study of the evolved stellar populations in the dwarf spheroidal galaxy Fornax based on wide-area near-infrared observations, aimed at obtaining new independent estimates of its distance and metallicity distribution. Assessing the reliability of near-infrared methods is most important in view of future space- and ground-based deep near-infrared imaging of resolved stellar systems.

Aims.This paper investigates the peculiar behaviour of the light even (alpha-elements) and odd atomic number elements in red giants in the galactic bulge, both in terms of the chemical evolution of the bulge, and in terms of possible deep-mixing mechanisms in these evolved stars.

Aims.We present an analysis of FLAMES-Giraffe spectra for several bright giants in NGC 6441, to investigate the presence and extent of the Na-O anticorrelation in this anomalous globular cluster.

Context.Metal-rich globular clusters trace the formation of bulges. Abundance ratios in the metal-rich globular clusters such as NGC 6553 can constrain the formation timescale of the Galactic bulge.

Aims.We spectroscopically characterize the Galactic Bulge to infer its star formation timescale, compared to the other Galactic components, through the chemical signature on its individual stars.

Aims.We derive the structure, distribution of MS and PMS stars and dynamical state of the young open cluster NGC 4755. We explore the possibility that, at the cluster age, some MS and PMS stars still present infrared excesses related to dust envelopes and proto-planetary discs.

Context.Metal-poor globular clusters in the bulge are important tracers of early chemical evolution. HP-1 is among the six metal-poor clusters within 5° of the Galactic center, and could be the one closest to the centerAims.The main purpose of this study is the determination of metallicity and elemental ratios. Methods.High resolution spectra of two giants of the bulge globular cluster HP-1 were obtained at the 8 m VLT UT2-Kueyen telescope with the UVES spectrograph. This is the second metal-poor globular cluster in the bulge for which a detailed abundance analysis is presented. Multiband $V,I,J,H,K_{\rm s}$photometry was used to derive effective temperatures.Results.The present analysis provides a metallicity [Fe/H] = $-1.00\pm0.2$. The α-elements oxygen and silicon show [ α/Fe] ≈+0.3, whereas magnesium, calcium and titanium show solar ratios. A proper motion analysis indicates that the two stars are cluster members. Conclusions.The metallicity is unexpected for a blue Horizontal Branch (BHB) cluster. HP-1 is the first known cluster with such a high metallicity combined with a BHB and a steep Red Giant Branch (RGB). Together with NGC 6388 and NGC 6441 of $\rm [Fe/H]\sim-0.6$it would be third with such characteristics, but it differs from them, since these two other clusters have also a populous Red HB, and a normal slope of the RGB for their metallicity, which is not the case of HP-1.

Aims.Updated data of the 153 Galactic globular clusters are used to readdress fundamental parameters of the Milky Way, such as the distance of the Sun to the Galactic centre, the bulge and halo structural parameters, and cluster destruction rates.Methods.We build a reduced sample that has been decontaminated of all the clusters younger than 10 Gyr and of those with retrograde orbits and/or evidence of relation to dwarf galaxies. The reduced sample contains 116 globular clusters that are tested for whether they were formed in the primordial collapse.Results.The 33 metal-rich globular clusters ($\rm [Fe/H]\geq-0.75$) of the reduced sample basically extend to the Solar circle and are distributed over a region with the projected axial-ratios typical of an oblate spheroidal, $\Delta x:\Delta y:\Delta z\approx1.0:0.9:0.4$. Those outside this region appear to be related to accretion. The 81 metal-poor globular clusters span a nearly spherical region of axial-ratios ${\approx}1.0:1.0:0.8$extending from the central parts to the outer halo, although several clusters in the external region still require detailed studies to unravel their origin as accretion or collapse. A new estimate of the Sun's distance to the Galactic centre, based on the symmetries of the spatial distribution of 116 globular clusters, is provided with a considerably smaller uncertainty than in previous determinations using globular clusters, $R_{\rm O}=7.2\pm0.3\,\rm kpc$. The metal-rich and metal-poor radial-density distributions flatten for $R_{\rm GC}\leq2\,\rm kpc$and are represented well over the full Galactocentric distance range both by a power-law with a core-like term and Sérsic's law; at large distances they fall off as ${\sim} R^{-3.9}$.Conclusions.Both metallicity components appear to have a common origin that is different from that of the dark matter halo. Structural similarities between the metal-rich and metal-poor radial distributions and the stellar halo are consistent with a scenario where part of the reduced sample was formed in the primordial collapse and part was accreted in an early period of merging. This applies to the bulge as well, suggesting an early merger affecting the central parts of the Galaxy. The present decontamination procedure is not sensitive to all accretions (especially prograde) during the first Gyr, since the observed radial density profiles still preserve traces of the earliest merger(s). We estimate that the present globular cluster population corresponds to ${\leq}23\pm6\%$of the original one. The fact that the volume-density radial distributions of the metal-rich and metal-poor globular clusters of the reduced sample follow both a core-like power-law, and Sérsic's law indicates that we are dealing with spheroidal subsystems at all scales.

We present BVIphotometry of the globular cluster NGC 6642 using the SOI imager at the SOAR Telescope. The colour magnitude diagrams (CMD) reach ≈1.5 mag in Vbelow the main sequence turn-off. A comparison of the overall sequences, and in particular the Red Giant Branch slope of NGC 6642 with that of M 5, indicates that the two clusters must have a similar metallicity of [Fe/H] ≈–1.3. We also obtained a reddening $E(B-V)=0.42\pm0.03$for NGC 6642, and a distance from the Sun of $d_{\odot}=7.2\pm0.5$kpc. Therefore NGC 6642 is a moderately metal-poor globular cluster that is spatially located in the bulge at a galactocentric distance of $R_{\rm GC}\approx 1.7$kpc. The comparison of CMDs of NGC 6642 with those of M 5 shows that there is a very good match of magnitude difference between turn-off and horizontal branch, suggesting comparable ages. The age of M 5 is typical of halo globulars, so NGC 6642 is coeval with the halo. It is a good candidate as one of the few genuine metal-poor and old bulgeclusters, and might be one of the oldest fossils in the Galaxy.

In this work we present the detection of 33 star clusters and 51 candidates in one field of the near by galaxy M 33. This study is based on WFC/ACS images available from the HSTarchive. Thanks to the high resolving power, we were able to confirm that two candidates previously indicated by Christian & Schommer (1982, ApJS, 49, 405) are indeed star clusters. We list the main properties for the star clusters (and candidates), along with some peculiar objects, such as background galaxies and possible HII regions.

High resolution spectra of 5 giants, including a horizontal branch star, of the metal-rich globular cluster 47 Tucanae were obtained with the UVES spectrograph at the 8 m VLT UT2-Kueyen telescope. The atmospheric parameters (Teff, log g, [Fe/H], vt) were derived from VIJKphotometry and spectroscopic data based on Fe I and Fe II lines. Fe I and Fe II iron abundances and respective total errors [Fe I/H] = –$0.66 \pm0.12$and [Fe II/H] = –$0.69 \pm 0.24$are found. Abundances of α(O, Mg, Ca, Si, Ti), odd-Z (Na, Al), s- (Ba, La, Zr), and r-process (Eu) elements were determined by means of spectrum synthesis. The main results are $\rm [O/Fe] = +0.35 \pm 0.11$, [Mg/Fe] ≈[Si/Fe] ≈[Ti/Fe] = +$0.23 \pm 0.17$, $\rm [Ca/Fe] = 0.0 \pm 0.15$, $\rm [Ba/Fe] = +0.31 \pm 0.22$and $\rm [Eu/Fe] = +0.33 \pm 0.10$. Overabundances of the α-elements O, Mg, Si and Ti, and of Eu are similar to those seen in halo metal-poor stars, whereas a solar Ca-to-Fe ratio resembles the values found in bulge stars. An overall metallicity $Z=0.006$or [M/H] = –0.45 is thus obtained, as is a mean heliocentric radial velocity $v_{\rm r}^{\rm hel}\,=\,-22.43 \pm 1.99$km s-1.

BVphotometry of the faint open clusters Berkeley 36, Berkeley 73 and Biurakan 13 are studied. For these clusters no colour–magnitude analyses were previously available. The colour–magnitude Diagrams indicate that they are all old open clusters. The derived ages are ~4 Gyr for Berkeley 36, and ~2.3 Gyr for both Berkeley 73 and Biurakan 13. The clusters are not very reddened, with $E(B-V)$= 0.25, 0.10 and 0.30 respectively for Berkeley 36, Berkeley 73 and Biurakan 13. Berkeley 36 and Berkeley 73 are located at a distance from the Galactic center of ~10 kpc, while Biurakan 13 is much farther, at 15 kpc. A peak in the age distribution appears at 5 Gyr suggesting a distinct star forming event in the disk.

High resolution spectra of five stars in the bulge globular cluster NGC 6528 were obtained at the 8m VLT UT2-Kueyen telescope with the UVES spectrograph. Out of the five stars, two of them showed evidence of binarity. The target stars belong to the horizontal and red giant branch stages, at $4000 < T_{\rm eff}< 4800$K. Multiband V, I, J, H, Ksphotometry was used to derive initial effective temperatures and gravities. The main purpose of this study is the determination of metallicity and elemental ratios for this template bulge cluster, as a basis for the fundamental calibration of metal-rich populations. The present analysis provides a metallicity $\rm [Fe/H] = -0.1\pm0.2$and the α-elements O, Mg and Si, show [ α/Fe] ≈+0.1, whereas Ca and Ti are around the solar value or below, resulting in an overall metallicity Z ≈$Z_{\odot}$.

We present the results of a VLT polarimetric monitoring campaign of the GRB 020813 optical afterglow carried out in three nights, from 0.88 to 4.20 days after the gamma-ray event. The mean values of the degree of linear polarization (P) and its position angle (θ) resulting from our campaign are $\langle P\rangle=1.18 \pm 0.10 \%$and $\langle \theta\rangle = 148.7^{\circ} \pm 2.3^{\circ}$, after correcting for Galactic interstellar polarization. Our VLT data set is most naturally described by a constant degree of linear polarization and position angle, nonetheless a slow θevolution cannot be entirely ruled out by our data. The VLT monitoring campaign did not reveal either a significant θrotation respect to the Keck spectropolarimetric observations performed ~0.25 days after the GRB (Barth et al. [CITE]). However, $\langle P\rangle $is a factor of two lower than the polarization degree measured from Keck. Additionally, the VLT polarization data allowed us to construct an accurate V-band light curve. The V-band photometric data revealed a smooth light curve with a break located between the last Keck and our first VLT polarimetric measurement, $0.33 < t_{{\rm break}, V} < 0.88$days after the GRB. The typical magnitude fluctuations of the VLT V-band lightcurve are 0.003 mag, 0.010 mag and 0.016 mag for our three observing nights, respectively. We speculate that the stability of θmight be related to the smoothness of the light curve.

The polarization curve of GRB 020813 is discussed and compared to different models for the structure, evolution and magnetisation properties of the jet and the interstellar medium onto which the fireball impacts. GRB 020813 is best suited for this kind of analysis for the smoothness of its afterglow light curve, ensuring the applicability of current models. The polarization dataset allows us to rule out the standard GRB jet, in which the energy and Lorentz factor have a well defined value inside the jet opening angle and the magnetic field is generated at the shock front. We explore alternative models finding that a structured jet or a jet with a toroidal component of the magnetic field can fit equally well the polarization curve. Stronger conclusions cannot be drawn due to the incomplete sampling of the polarization curve. A more dense sampling, especially at early times, is required to pin down the structure of the jet and the geometry of its magnetic field.

In a previous paper we reported on a discontinuity in the extreme horizontal branch (EHB) of the Galactic globular cluster NGC 6752, which we called the second U-jump. This feature was attributed to a combination of post zero-age horizontal branch evolution and diffusion effects. In this follow-up study we analyze other EHB clusters and show that the second U-jump is a common feature among EHB clusters reaching $T_{\rm eff}\ge 23\,000$K, and that its onset in different clusters converges around $T_{\rm eff}\sim 21\,000$±3000 K. We also present near-ultraviolet diagrams of ωCen and NGC 2808, the only two objects with spectroscopically confirmed “blue hook” stars ($T_{\rm eff}\ge 35\,000$K). We confirm predictions of a photometric discontinuity separating late from early-helium flashers. Moreover, we present empirical evidence that the second U-jump population might be mainly composed of early-helium flashers. Lastly, we revisit the discussion on the ubiquitous nature of the gaps and jumps so far identified in the blue HB tails, suggesting a possible discrete nature of the distribution in temperature of the HB stars.

A detailed abundance analysis of 5 giants of the metal-rich bulge globular cluster NGC 6553 was carried out using high resolution infrared spectra in the Hband, obtained at the Gemini-South 8m telescope. JKphotometry collected at ESO and VI photometry from the Hubble Space Telescope are used to derive effective temperatures. The present analysis provides a metallicity $\rm [Fe/H] = -0.20\pm 0.10$. An overabundance of oxygen of $\rm [O/Fe] = +0.20$is found from IR OH lines.

We address the issue whether the central parts of the Galaxy harbour young clusters other than Arches, Quintuplet and the Nuclear Young Cluster. A large sample of centrally projected cluster candidates has been recently identified from the 2MASS $J, H$and KsAtlas. We provide a catalogue of higher angular resolution and deeper images for 57 2MASS cluster candidates, obtained with the near-IR camera SOFI at the ESO NTT telescope. We classify 10 objects as star clusters, some of them deeply embedded in gas and/or dust clouds. Three other objects are probably star clusters, although the presence of dust in the field does not exclude the possibility of their being field stars seen through low-absorption regions. Eleven objects are concentrations of stars in areas of little or no gas, and are classified as dissolving cluster candidates. Finally, 31 objects turned out to be the blend of a few bright stars, not resolved as such in the low resolution 2MASS images. By combining the above results with other known objects we provide an updated sample of 42 embedded clusters and candidates projected within 7°. As a first step we study Object 11 of Dutra & Bica ([CITE]) projected at $\approx $1° from the nucleus. We present Hand Ksphotometry and study the colour-magnitude diagram and luminosity function. Object 11 appears to be a less massive cluster than Arches or Quintuplet, and it is located at a distance from the Sun $d_{\odot} \approx$8 kpc, with a visual absorption $A_{V} \approx 15$.

In this paper we report on a curious feature in the V, ($U-B$) color-magnitude diagrams of globular clusters. In our database, we find that a considerable fraction of blue horizontal branch stars, hotter than the instability strip and cooler than the Grundahl et al. (1999) jump (i.e., $6000 \lesssim T_{\rm eff}\rm (K)\lesssim 10\,000$), have ($U-B$) colors redder than their red giant progenitors. This red incursion is not expected on theoretical grounds, as horizontal branch stars (whose convective regions are less extended than in red giant structures) should not “appear” cooler than a red giant. Analyzing data from different telescopes we show that: 1) the horizontal branch red incursion is strongly dependent on the shape of the adopted Ufilter and to a lesser extent, on the Bfilter; 2) the photometry done with Ufilters that do not encompass the Balmer jump shows the blue horizontal branch red incursion; 3) the occurrence of this feature is also due to the peculiar dependence of the Uand Bmagnitudes on star effective temperature, gravity, and metallicity; 4) theoretical tracks can reproduce the observed horizontal branch morphology, provided that the appropriate (i.e. exactly responding to the filters effectively used in the observations) transmission curve efficiencies are used for deriving color-Tefftransformations; 5) the red incursion extent depends on metallicity.?

New near-infrared observations of NGC 6528 are presented. The JHKsobservations complement a previous HST/NICMOS data set by Ortolani et al. ([CITE]), in that they sample a larger area, contain a more numerous sample of red giant stars, and include the Kband. Also, archival HST data sets (separated by 6.093 years) were used to proper-motion decontaminate the near-infrared sample and extract a clean VJHKcatalogue. Using the present wide colour baseline, we compared the cleaned colour-magnitude diagrams of NGC 6528 with those of NGC 6553 and NGC 104 and derived new estimates of reddening and distance, $E_{\it B-V}=0.55$and ($m-M$)0=14.44 (7.7 kpc). Moreover, the morphology and location of the cleaned red giant branch were used to derive a photometricestimate of the cluster metallicity. The average of 10 metallicity indicators yields a mean value of $[M/H] \approx0.0$, and $\rm [Fe/H] \simeq -0.20$and +0.08 on the Zinn & West ([CITE]) and Carretta & Gratton ([CITE]) revised metallicity scale, respectively. The best isochrone fit to the cleaned $K,V-K$diagram is obtained for a 12.6 Gyr and $Z=0.02$isochrone, i.e. the derived metallicity of NGC 6528 turns out to be very close to the mean of stars in the Baade's Window.
Five AGB variable star candidates, whose membership has to be confirmed spectroscopically, are bolometrically as bright as the known long period variable stars in NGC 6553. As discussed in Guarnieri et al. ([CITE]) for NGC 6553, this may indicate that an “intermediate age” population is not needed to account for the brightest stars in external galaxies such as M 32.

Colour-Magnitude Diagrams are presented for the globular clusters NGC 6325 and NGC 6355. These clusters are embedded in crowded bulge fields. Both clusters are concentrated and have blue Horizontal Branches, and NGC 6325 shows a blue tail. We derive a reddening $E(B{-}V) \approx 0.95$and a distance from the Sun $d_{\odot} \approx 6.9$kpc for NGC 6325, and $E(B{-}V) \approx 0.78$and $d_{\odot} \approx 8.8$kpc for NGC 6355. They are both at ~1 kpc from the Galactic center, above the plane. The metallicity has been estimated based on red giant branch morphology, being consistent with an intermediate metallicity of $\rm [Fe/H] \approx -1.3$for both clusters, at the lower end of the metallicity distribution of bulge field stars. They add to the list of blue Horizontal Branch clusters with intermediate metallicities within the bulge volume.

Wilson & Bappu (1957) have shown the existence of a remarkable correlation between the width of the emission in the core of the K line of Ca $\!{\rm II}$and the absolute visual magnitude of late–type stars.
Here we present a new calibration of the Wilson–Bappu effect based on a sample of 119 nearby stars. We use, for the first time, width measurements based on high resolution and high signal to noise ratio CCD spectra and absolute visual magnitudes from the Hipparcosdatabase.
Our primary goal is to investigate the possibility of using the Wilson–Bappu effect to determine accurate distances to single stars and groups.
The result of our calibration fitting of the Wilson–Bappu relationship is $M_V=33.2{-}18.0 \log W_0$, and the determination seems free of systematic effects. The root mean square error of the fitting is 0.6 mag. This error is mostly accounted for by measurement errors and intrinsic variability of W0, but in addition a possible dependence on the metallicity is found, which becomes clearly noticeable for metallicities below $\rm [Fe/H]\sim-0.4$. This detection is possible because in our sample [Fe/H] ranges from -1.5 to 0.4.
The Wilson–Bappu effect can be used confidently for all metallicities not lower than ${\sim}{-}0.4$, including the LMC. While it does not provide accurate distances to single stars, it is a useful tool to determine accurate distances to clusters and aggregates, where a sufficient number of stars can be observed. 
We apply the Wilson–Bappu effect to published data of the open cluster M 67; the retrieved distance modulus is of 9.65 mag, in very good agreement with the best distance estimations for this cluster, based on main sequence fitting.

We present a new determination of the metallicity distribution, age, and luminosity function of the Galactic bulge stellar population. By combining near-IR data from the 2MASS survey, from the SOFI imager at ESO NTT and the NICMOS camera on board HST we were able to construct color-magnitude diagrams (CMD) and luminosity functions (LF) with large statistics and small photometric errors from the Asymptotic Giant Branch (AGB) and Red Giant Branch (RGB) tip down to ~$0.15~M_\odot$. This is the most extended and complete LF so far obtained for the galactic bulge. Similar near-IR data for a disk control field were used to decontaminate the bulge CMDs from foreground disk stars, and hence to set a stronger constraint on the bulge age, which we found to be as large as that of Galactic globular clusters, or $\ga$10 Gyr. No trace is found for any younger stellar population. Synthetic CMDs have been constructed to simulate the effect of photometric errors, blending, differential reddening, metallicity dispersion and depth effect in the comparison with the observational data. By combining the near-IR data with optical ones, from the Wide Field Imager at the ESO/MPG 2.2 m telescope, a disk-decontaminated (MK,V–K) CMD has been constructed and used to derive the bulge metallicity distribution, by comparison with empirical RGB templates. The bulge metallicity is found to peak at near solar value, with a sharp cutoff just above solar, and a tail towards lower metallicity that does not appreciably extend below [M/H] $\sim-1.5$.

An empirical calibration is presented for the synthetic Lick indices (e.g. Mg2, , Hβ, etc.) of Simple Stellar Population (SSP) models that for the first time extends up to solar metallicity. This is accomplished by means of a sample of Milky Way globular clusters (GCs) whose metallicities range from ~${\mathrm Z}_{\odot}/30$to $Z\sim{\mathrm Z}_{\odot}$, thanks to the inclusion of several metal rich clusters belonging to the Galactic bulge (e.g., NGC 6553 and NGC 6528). This metallicity range approaches the regime that is relevant for the interpretation of the integrated spectra of elliptical galaxies. It is shown that the spectra of both the globular clusters and the Galactic bulge follow the same correlation between magnesium and iron indices that extends to elliptical galaxies, showing weaker iron indices at given magnesium indices with respect to the predictions of models that assume solar-scaled abundances. This similarity provides robust empirical evidence for enhanced [ α/Fe]  ratios in the stellar populations of elliptical galaxies, since the globular clusters are independently known to have enhanced [ α/Fe]  ratios from spectroscopy of individual stars. We check the uniqueness of this α-overabundance solution by exploring the whole range of model ingredients and parameters, i.e. fitting functions, stellar tracks, and the initial mass function (IMF). We argue that the standardmodels (meant for solar abundance ratios) succeed in reproducing the Mg-Fe correlation at low metallicities ($[Z/H]\lesssim -0.7$) because the stellar templates used in the synthesis are Galactic halo stars that actually are α-enhanced. The same models, however, fail to predict the observed Mg-Fe pattern at higher metallicities ($[Z/H] \gtrsim -0.7$) (i.e., for bulge clusters and ellipticals alike) because the high-metallicity templates are disk stars that are not α-enhanced. We show that the new set of SSP models which incorporates the dependence on the [ α/Fe]   ratio (Thomas et al. 2003) is able to reproduce the Mg and Fe indices of GCs at all metallicities, with an α-enhancement α/Fe=+0.3, in agreement with the available spectroscopic determinations. The Hβindex and the higher-order Balmer indices are well calibrated, provided the appropriate morphology of the Horizontal Branch is taken into account. In particular, the Balmer line indices of the two metal rich clusters NGC 6388 and NGC 6441, which are known to exhibit a tail of warm Horizontal Branch stars, are well reproduced. Finally, we note that the Mg indices of very metal-poor ($[Z/H]\lesssim -1.8$) populations are dominated by the contribution of the lower Main Sequence, hence are strongly affected by the present-day mass function of individual globular clusters, which is known to vary from cluster to cluster due to dynamical effects.

We have analysed the optical polarimetric properties of nearby intermediate-late type MS stars and examined in some detail the pecularities displayed by those known to have planets. We find that i) the polarization degree is not strictly correlated with the presence of planets; ii) there is a lack of high eccentricity planets at high optical linear polarization levels; iii) no clear correlation is seen between metallicity and polarization amongst extra-solar systems; iv) the contribution to the polarization by the interstellar medium seems to become effective only after ~70 pc.

We present a comprehensive spectroscopic study of the integrated light of metal-rich Galactic globular clusters and the stellar population in the Galactic bulge. We measure line indices which are defined by the Lick standard system and compare index strengths of the clusters and Galactic bulge. Both metal-rich globular clusters and the bulge are similar in most of the indices, except for the CN index. We find a significant enhancement in the CN$/\langle$Fe$\rangle$index ratio in metal-rich globular clusters compared with the Galactic bulge. The mean iron index $\langle$Fe$\rangle$of the two metal-rich globular clusters NGC 6528 and NGC 6553 is comparable with the mean iron index of the bulge. Index ratios such as Mgb$/\langle$Fe$\rangle$, Mg$_2/\langle$Fe$\rangle$, Ca 4227$/\langle$Fe$\rangle$, and TiO$/\langle$Fe$\rangle$, are comparable in both stellar population indicating similar enhancements in individual elements which are traced by the indices. From the globular cluster data we fully empirically calibrate several metallicity-sensitive indices as a function of [Fe/H] and find tightest correlations for the Mg2index and the composite [MgFe] index. We find that all indices show a similar behavior with galactocentric radius, except for the Balmer series, which show a large scatter at all radii. However, the scatter is entirely consistent with the cluster-to-cluster variations in the horizontal branch morphology.

We present and discuss polarimetric observations performed with the VLT–UT3 (Melipal) on the afterglow of GRB 011211, ~35 hours after the burst onset. The observations yielded a 3 σupper limit of $P<2.7\%$. We discuss this result in combination with the lightcurve evolution, that may show a break approximately at the time of our observation. We show that our upper limit is consistent with the currently favored beamed fireball geometry, especially if the line of sight was not too close to the edge of the cone.

We present UBVCCD observations obtained in the field of the northern open cluster NGC 1220, for which little information is available. We provide also BVCCD photometry of a field 5′ northward of NGC 1220 to take into account field star contamination. We argue that NGC 1220 is a young compact open cluster, for which we estimate a core radius in the range  arcmin. We identify 26 likely candidate members with spectral type earlier than $A5$, down to $V_{\rm o}=15.00$mag on the basis of the position in the two-colour Diagram and in the Colour Magnitude Diagrams (CMDs). By analyzing the distribution of these stars in the colour-colour and CMDs, we find that NGC 1220 has a reddening $E(B-V)=0.70\pm0.15$mag, is placed $1800\pm200$pc distant from the Sun, and has an age of about 60 Myrs. The cluster turns out to be located about 120 pc above the Galactic plane, relatively high with respect to its age.

Pismis 23 and Stephenson 2 are two very reddened open clusters, projected close to the Galactic plane. We present VIand JHphotometry for Pismis 23 and Iand Gunn zfor Stephenson 2. We derive a relatively old age of ~700 Myr for Pismis 23, with a reddening value of $E(B-V) = 1.73$and a distance $d_{\odot}\approx 2.6$kpc from the Sun. Stephenson 2 has a clump of red supergiants, indicating a young age of about 20 Myr, somewhat younger and more distant ($d_{\odot}\approx 6$kpc) than recently reported in the literature. The age estimate for such a young object is crucial for the distance estimate. The high reddening of these two clusters relative to predictions from the diffuse interstellar medium at their distances is due to discrete intervening clouds.

High resolution spectra of a magnified bulge star were obtained at the 8 m Kueyen VLT-UT2 telescope with the UVES spectrograph. The source is a bulge giant of baseline magnitude $V_{\rm EROS} = 18.4$, magnified to $V \approx 18.0$. These data allow us to derive the stellar parameters of effective temperature $T_{\rm eff} \sim 3800$K, gravity log $g \sim 1.0$, reddening $E(B-V) \sim 0.7$, metallicity and and [O/Fe] ≈0.0 for EROS-BLG-2000-5. The giant appears to be located in the far side of the bulge.

Terzan 1 is the globular cluster with closest projection relative to the Galactic center. We report radial velocities and metallicities of 17 stars in order to investigate their membership in the cluster. From the 11 probable members of Terzan 1, a radial velocity of $v_{\rm r} = 114 \pm 14$km s-1is obtained. For this sample an intermediate metallicity of ${\rm [Fe/H]}\approx -1.3$is found, in agreement with previous work based on HST Colour-Magnitude Diagrams.

We analyze the colour magnitude diagram of the field population in the direction of the bulge cluster NGC 6553 to discuss the stellar field component projected towards the cluster. In particular we investigate the nature of a peculiar feature, called "red flare" which appears as a faint turnoff, located 2 mag about below the turnoff of the cluster, with a sparse trace of a sub-giant branch just above. A detailed modeling shows that the red flare is consistent with the expected location of the turnoff and sub-giant branch of the bulge population, once that the appropriate metallicity range and spatial distribution of the bulge stars are adopted. From the data, hints can be derived about the spatial shape and the basic stellar parameters of the bulge.

Low resolution spectra of 23 stars towards the bulge globular clusters NGC 6528 and NGC 6553 are analysed. Radial velocities and atmospheric parameters are derived in order to check their membership in the clusters. Effective temperatures were obtained from photometric data for stars with $T_{\rm eff} > 3800$K, whereas for cooler stars, they were derived from equivalent widths of TiO bands. Calibrations of W(TiO) as a function of stellar parameters based on a grid of synthetic spectra are presented. Metallicities were derived from a comparison of the observed spectra to a grid of synthetic spectra. The sample comprises evolutionary stages from the Red Giant Branch to the Horizontal Branch, with parameters in the range $3200 \leq T_{\rm eff} \leq 5000$K and $-0.5 \leq \log g \leq 2.4$. The mean metallicities obtained for NGC 6528 and NGC 6553 are [ Fe/H$] \approx -0.5$and -0.7, in both cases with [ Mg/Fe$] = +0.3$; assuming the same overabundance for the αelements O, Mg, Si, S, Ca and Ti, this gives $[Z/Z_{\rm \odot}] = -0.25$and -0.45. Membership verification by means of low resolution spectra is a crucial step in preparing targets for high resolution spectroscopy with 8 m class telescopes.

We present results from NICMOS Hubble Space Telescope observations of the reddened bulge globular clusters NGC 6528, Terzan 5, Liller 1, UKS 1 and Terzan 4, obtained through the filters F110W (1.1 μm) and F160W (1.6 μm) (nearly equivalent to Jand H). For the first time the turnoff region of Liller 1 and the main sequence of Terzan 5 and Terzan 4 are reached, as well as the horizontal branch of UKS 1. The magnitude difference between the turnoff and the red horizontal branch $\Delta m_{110}=m_{110}^{\rm HB}- m_{110}^{\rm TO}$is used as an age indicator. From comparisons with new isochrones in the NICMOS photometric system, we conclude that the two metal-rich clusters NGC 6528 and Terzan 5 are coeval within uncertainties (~$20\%$) with 47 Tucanae. Liller 1 and UKS 1 are confirmed as metal-rich globular clusters. Terzan 4 is confirmed as an interesting case of a metal-poor cluster in the bulge with a blue horizontal branch.

For the first time Colour-Magnitude Diagrams are presented for NGC 6569 and Palomar 11. NGC 6569 is a rather concentrated cluster whereas Palomar 11 is loose and sparsely populated. Cluster parameters are derived from Vand Iphotometry. These are red Horizontal Branch globular clusters, with metallicities comparable to that of 47 Tucanae. We derive a reddening $E(B-V) \approx 0.53$and a distance from the Sun $d_{\odot} \approx 9.8$kpc for NGC 6569, and $E(B-V) \approx 0.35$and $d_{\odot} \approx 13.2$kpc for Palomar 11. NGC 6569 is located in the bulge, while Palomar 11, despite its rather high metallicity, is in the inner halo, a rare case similar to that of 47 Tucanae.

We report CCD optical (Band Vpassbands) and near IR (Jand Kbands) observations in the region of the old open cluster NGC 2141. By combining the two sets of photometry (500 stars in common) we derive new estimates of the cluster's fundamental parameters. We confirm that the cluster is 2.5 Gyrs old, but, with respect to previous investigations, we obtain a slightly larger reddening ($E(B-V) = 0.40$), and a slightly shorter distance (3.8 kpc) from the Sun. Finally, we present the Luminosity Function (LF) in the Vband, which is another age indicator. We provide a good fit for the age range inferred from isochrones by assuming the Kroupa et al. ([CITE]) IMF up to MV= 5.0. We interpret the disagreement at fainter magnitudes as evidence of mass segregation.

Colour-magnitude diagrams are presented for the first time, of the faint southern star cluster UKS 2, which was for a long time reported as a globular cluster candidate.
The Vvs. $B-V$diagrams indicate that UKS 2 is an open cluster with age comparable to that of the Hyades.
It has a reddening of $E(B-V) = 0.40$and is located at a distance from the Sun of $d_{\odot}$≈7 kpc. The cluster is located outside the solar radius at galactocentric distance projected on the plane rGC≈11 kpc, and a height $z \approx -370$pc.

We present Vand Iphotometry of the globular clusters Terzan 9 and NGC 6453 for the first time, and also of NGC 6139. The three clusters are projected towards the bulge. The Colour-Magnitude Diagram morphologies reveal that the sample clusters have blue horizontal branches. This characterizes an important fraction of the clusters projected on the bulge, with implications on the early Galaxy history. From the colour-magnitude diagrams we derive reddenings of $E(B-V) = 1.95, 0.77, 0.70$and distances $d_{\odot}\approx 4.9$, 9.4, 8.5 kpc respectively for Terzan 9, NGC 6139 and NGC 6453. We conclude that these metal-poor clusters are within the bulge volume.

We present Vand Icolour-magnitude diagrams of the star clusters ESO 93-SC08 and ESO 452-SC11. Both clusters are poorly populated, and the colour-magnitude diagrams show that ESO 93-SC08 is an intermediate age open cluster, while ESO 452-SC11 is confirmed as a globular cluster. The magnitude difference between the turnoff and the clump/horizontal branch indicates an age of $4 - 5$Gyr for ESO 93–SC08, while ESO 452–SC11 has an age comparable to the average of the halo globular clusters. ESO 93–SC08 has a reddening of $E(B-V)$= 0.64 and is located at $d_{\odot}\approx 13.7 $kpc from the Sun. It is a distant open cluster in the outer disk. ESO 452–SC11 appears to be a southern counterpart of the Palomar clusters. We derive a reddening of $E(B-V) = 0.58$, a distance $d_{\odot}\approx 6.5 $kpc and a metallicity $[$Fe/H$]$≈-1.5 for ESO 452–SC08. The deep CMD shows evidence of depletion at the lower main sequence, similarly to other poorly populated globular clusters.

We present photometry of the globular clusters NGC 6256 in V, I, NGC 6717, NGC 6256 in V, I, and NGC 6717 in B, V, obtaining cluster parameters. NGC 6256 has a post core-collapse structure, while such feature is suspected for NGC 6717. Both clusters are projected on the bulge. From the colour-magnitude diagrams for NGC 6256 we derive reliable cluster parameters which considerably revise its properties, with respect to previous literature. It has a blue-extended Horizontal Branch already observed in other post-core collapse clusters in the bulge, such as HP1. We derive a reddening of $E(B-V) = 1.10$, a distance $d_{\odot} \approx 6.4$kpc, and an intermediate metallicity for NGC 6256. NGC 6717 presents a blue Horizontal Branch. We derive a reddening of $E(B-V) = 0.23$and a distance $d_{\odot} \approx 7.1$kpc, locating the cluster in the bulge. The photometry is deep and we study the luminosity function, which presents some evidence of depletion of Main Sequence stars. This effect is not unexpected for such a poorly populated Palomar cluster in the bulge. We also estimate the cluster age from the magnitude difference between the horizontal branch and the turnoff. We obtain $\Delta V^{\rm TO}_{\rm HB} = 3.7$, which would place this intermediate metallicity bulge globular as coeval with the halo.

Colour magnitude diagrams of Terzan 3 and IC 1276 are presented for the first time. The morphology of the horizontal and red giant branches indicates that they are metal rich ([Fe/H] $\approx -0.7$). They are considerably reddened, with $E(B-V) = 0.72$(Terzan 3) and $E(B-V) = 1.16$(IC 1276). Terzan 3 is located at a distance from the Sun $d_{\odot}$≈6.5 kpc, and IC 1276 at $d_{\odot}$≈4.0 kpc. Both clusters are in the Galactic Bulge. The photometries attain the main sequence turnoff regions, and a discussion of ages is given as compared to other bulge and halo globular clusters.