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Context. Sulfur (S) is one of the lesser-studied α-elements. Published investigations of its behavior have so far focused on local stars, and only a few clusters of the Milky Way have been considered to study this topic. We aim to study the S content of the globular cluster Ruprecht 106 – which has never before been studied for this purpose, but is known to present low levels of the [α/Fe] abundance ratio – and the open cluster Trumpler 5. The only star studied so far in Trumpler 5 shows an unexpectedly low abundance of S. Aims. With this work, we aim to provide the first S abundance in Ruprecht 106 and to investigate the S content of Trumpler 5 with a larger sample of stars. The open cluster Trumpler 20 is considered as a reference object. Methods. We performed a standard abundance analysis based on 1D model atmospheres in local thermodynamical equilibrium (LTE) and on high-resolution and high-signal-to-noise-ratio UVES-slit and UVES/FLAMES spectra. We also applied corrections for nonLTE. The metallicities of the targets were obtained by studying equivalent widths. Sulfur abundances were derived from multiplets 1, 6, and 8 by spectrosynthesis. Results. We find that the metallicities of Ruprecht 106 and Trumpler 5 are [Fe/H] = −1.37±0.11 and [Fe/H] = −0.49±0.14, respectively. Ruprecht 106 is less S-rich than the other Galactic clusters at similar metallicity. The low S content of Ruprecht 106, [S/Fe]NLTE = −0.52±0.13, is consistent with its shortage of α-elements. This supports an extra-galactic origin of this cluster. We obtained a new and more robust S content value of Trumpler 5 of about [S/Fe]NLTE = 0.05±0.20. According to our results, Trumpler 5 follows the trend of the Galactic disk in the [S/Fe]LTE versus [Fe/H] diagram. Our results for Trumpler 20, of namely [Fe/H]= 0.06±0.15 and [S/Fe]NLTE = −0.28±0.21, are in agreement with those in the literature. [ABSTRACT FROM AUTHOR]

Context. The small- to intermediate-mass (M < 0.8 M⊙), most metal-poor stars that formed in the infancy of the Universe are still shining today in the sky. They are very rare, but their discovery and investigation brings new knowledge on the formation of the first stellar generations. Aims. SDSS J102915.14+172927.9 is one of the most metal-poor star known to date. Since no carbon can be detected in its spectrum, a careful upper limit is important, both to classify this star and to distinguish it from the carbon-enhanced stars that represent the majority at these metallicities. Methods. We undertook a new observational campaign to acquire high-resolution UVES spectra. The new spectra were combined with archival spectra in order to increase the signal-to-noise ratio. From the combined spectrum, we derived abundances for seven elements (Mg, Si, Ca, Ti, Fe, Ni, and a tentative Li) and five significant upper limits (C, Na, Al, Sr, and Ba). Results. The star has a carbon abundance A(C) < 4.68 and therefore is not enhanced in carbon, at variance with the majority of the stars at this Fe regime, which typically show A(C) > 6.0. A feature compatible with the Li doublet at 670.7 nm is tentatively detected. Conclusions. The upper limit on carbon implies Z < 1.915 × 10−6, more than 20 times lower than the most iron-poor star known. Therefore, the gas cloud out of which the star was formed did not cool via atomic lines but probably through dust. Fragmentation of the primordial cloud is another possibility for the formation of a star with a metallicity this low. [ABSTRACT FROM AUTHOR]

We report the discovery of two Li-rich giant stars (fainter than the red giant branch (RGB) bump) in the stellar system Omega Centauri using GIRAFFE-FLAMES spectra. These two stars have A(Li) = 1.65 and 2.40 dex and they belong to the main population of the system ([Fe/H] = –1.70 and –1.82, respectively). The most Li-rich of them (#25664) has [Na/Fe] = +0.87 dex, which is ~0.5 dex higher than those measured in the most Na-rich stars of Omega Centauri of similar metallicity. The chemical abundances of Li and Na in #25664 can be qualitatively explained by deep extra mixing efficient within the star during its RGB evolution or by super-asymptotic giant branch (AGB) stars with masses between ~7 and 8 M⊙. In the latter scenario, this Li/Na-rich star could be formed from the pure ejecta of super-AGB stars before the dilution with pristine material occurs, or, alternatively, be part of a binary system having experienced mass transfer from the companion when this latter evolved through the super-AGB phase. In both these cases, the chemical composition of this unique object could allow to look for the first time at the chemical composition of the gas processed in the interior of super-AGB stars. [ABSTRACT FROM AUTHOR]

We present the abundance analysis for a sample of 18 red giant branch stars in the metal-poor globular cluster NGC 4147 based on medium- and high-resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Y, Ba, and Eu. We find a metallicity of [Fe/H] = -1.84 ± 0.02 and an α-enhancement of +0.38 ± 0.05 (errors on the mean), typical of halo globular clusters in this metallicity regime. A significant spread is observed in the abundances of light elements C, N, O, Na, and Al. In particular, we found an Na-O anticorrelation and Na-Al correlation. The cluster contains only ~15 per cent of stars that belong to the first generation (Na-poor and O-rich). This implies that it suffered a severe mass-loss during its lifetime. Its [Ca/Fe] and [Ti/Fe] mean values agree better with the Galactic halo trend than with the trend of extragalactic environments at the cluster metallicity. This possibly suggests that NGC 4147 is a genuine Galactic object at odd with what claimed by some author that proposed the cluster to be member of the Sagittarius dwarf galaxy. An antirelation between the light s-process element Y and Na may also be present. [ABSTRACT FROM AUTHOR]

Context. Low-mass dwarf spheroidal galaxies are key objects for our understanding of the chemical evolution of the pristine Universe and the Local Group of galaxies. Abundance ratios in stars of these objects can be used to better understand their star formation and chemical evolution. Aims. We report on the analysis of a sample of 11 stars belonging to five different ultra-faint dwarf spheroidal galaxies (UfDSph) that is based on X-Shooter spectra obtained at the VLT. Methods. Medium-resolution spectra have been used to determine the detailed chemical composition of their atmosphere. We performed a standard 1D LTE analysis to compute the abundances. Results. Considering all the stars as representative of the same population of low-mass galaxies, we found that the [ff/Fe] ratios vs.s [Fe/H] decreases as the metallicity of the star increases in a way similar to that which is found for the population of stars that belong to dwarf spheroidal galaxies. The main difference is that the solar [ff/Fe] is reached at a much lower metallicity for the UfDSph than for the dwarf spheroidal galaxies. We report for the first time the abundance of strontium in CVn II. The star we analyzed in this galaxy has a very high [Sr/Fe] and a very low upper limit of barium which makes it a star with an exceptionally high [Sr/Ba] ratio. [ABSTRACT FROM AUTHOR]

Context. The tidal disruption of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) is producing the most prominent substructure in the Milky Way (MW) halo, the Sagittarius Stream. Aside from field stars, it is suspected that the Sgr dSph has lost a number of globular clusters (GC). Many Galactic GC are thought to have originated in the Sgr dSph. While for some candidates an origin in the Sgr dSph has been confirmed owing to chemical similarities, others exist whose chemical composition has never been investigated. Aims. NGC 5053 and NGC 5634 are two of these scarcely studied Sgr dSph candidate-member clusters. To characterize their composition we analyzed one giant star in NGC 5053, and two in NGC 5634. Methods. We analyze high-resolution and signal-to-noise spectra by means of the MyGIsFOS code, determining atmospheric parameters and abundances for up to 21 species between O and Eu. The abundances are compared with those of MW halo field stars, of unassociated MW halo globulars, and of the metal-poor Sgr dSph main body population. Results. We derive a metallicity of [Fe II/H] = -2:26 ± 0:10 for NGC 5053, and of [Fe I/H] = 1:99 ± 0:075 and -1:97 ± 0:076 for the two stars in NGC 5634. This makes NGC 5053 one of the most metal-poor globular clusters in the MW. Both clusters display an α enhancement similar to the one of the halo at comparable metallicity. The two stars in NGC 5634 clearly display the Na-O anticorrelation widespread among MW globulars. Most other abundances are in good agreement with standard MW halo trends. Conclusions. The chemistry of the Sgr dSph main body populations is similar to that of the halo at low metallicity. It is thus difficult to discriminate between an origin of NGC 5053 and NGC 5634 in the Sgr dSph, and one in the MW. However, the abundances of these clusters do appear closer to that of Sgr dSph than of the halo, favoring an origin in the Sgr dSph system. [ABSTRACT FROM AUTHOR]

Keywords: stars: Population II; stars: abundances; Galaxy: abundances; Galaxy: halo; errata, addenda EN stars: Population II stars: abundances Galaxy: abundances Galaxy: halo errata, addenda 1 1 1 10/03/22 20220929 NES 220929 We realised that there was a mistake in the code that computed parameters for the photometric data sample. Furthermore, for 301 763 stars, the interpolation arrived at the edge in metallicity of the synthetic grid (+0.5) and the program was not extrapolating. Stars: Population II, stars: abundances, Galaxy: abundances, Galaxy: halo, errata, addenda. [Extracted from the article]

Context. The abundances of α-elements are a powerful diagnostic of the star formation history and chemical evolution of a galaxy. Sulphur, being moderately volatile, can be reliably measured in the interstellar medium (ISM) of damped Ly-α galaxies and extragalactic Hii regions. Measurements in stars of different metallicity in our Galaxy can then be readily compared to the abundances in external galaxies. Such a comparison is not possible for Si or Ca that suffer depletion onto dust in the ISM. Furthermore, studying sulphur is interesting because it probes nucleosynthetic conditions that are very different from those of O or Mg. In this context measurements in star clusters are a reliable tracers of the Galactic evolution of sulphur. Aims. The aim of this paper is to determine sulphur abundances in several Galactic clusters that span a metallicity range −1.5 < [Fe/H] < 0.0. Methods. We use a standard abundance analysis, based on 1D model atmospheres in local thermodynamical equilibrium (LTE) and literature corrections for non-LTE (NLTE), as well as 3D corrections based on hydrodynamical model atmospheres, to derive sulphur abundances in a sample of stars in the globular cluster M4, and the open clusters Trumpler 5, NGC2477, and NGC 5822. Results. We find A (S)NLTE = 6.11 ± 0.04 for M4, A (S)NLTE = 7.17 ± 0.02 for NGC2477, and A (S)NLTE = 7.13 ± 0.06 for NGC5822. For the only star studied in Trumpler 5 we find A(S)NLTE = 6.43 ± 0.03 and A(S)LTE = 6.94 ± 0.05. Conclusions. Our measurements show that, by and large, the S abundances in Galactic clusters trace reliably those in field stars. The only possible exception is Trumpler 5, for which the NLTE sulphur abundance implies an [S/Fe] ratio lower by roughly 0.4 dex than observed in field stars of comparable metallicity, even though its LTE sulphur abundance is in line with abundances of field stars. Moreover the LTE sulphur abundance is consistent only with the abundance of another α-element, Mg, in the same star, while the low NLTE value is consistent with Si and Ca. We believe that further investigation of departures from LTE is necessary, as well as observation of other S i lines in this star and in other stars of the same cluster, before one can conclude that the sulphur abundance in Trumpler 5 is indeed 0.4 dex lower than in field stars of comparable metallicity. The S abundances in our sample of stars in clusters imply that the clusters are chemically homogeneous for S within 0.05 dex. [ABSTRACT FROM AUTHOR]

Context. The existence of lithium-rich low-mass red giant stars still represents a challenge for stellar evolution models. Stellar clusters are privileged environments for this kind of investigation. Aims. To investigate the chemical abundance pattern of the old open cluster Trumpler 5, we observed a sample of four red-clump stars with high-resolution optical spectrographs. One of them (#3416) reveals extremely strong lithium lines in its spectrum. Methods. One-dimensional, local thermodynamic equilibrium analysis was performed on the spectra of the observed stars. A 3DNLTE analysis was performed to derive the lithium abundance of star #3416. Results. Star #3416 is super Li-rich with A(Li) = 3.75 dex. The lack of 6Li enrichment (6Li/7Li < 2%), the low carbon isotopic ratio (12C/13C = 14 ± 3), and the lack of evidence for radial velocity variation or enhanced rotational velocity (v sin i = 2.8 km s-1) all suggest that lithium production has occurred in this star through the Cameron & Fowler mechanism. Conclusions. We identified a super Li-rich core helium-burning, red-clump star in an open cluster. Internal production is the most likely cause of the observed enrichment. Given the expected short duration of a star's Li-rich phase, enrichment is likely to have occurred at the red clump or in the immediately preceding phases, namely during the He-flash at the tip of the red giant branch (RGB) or while ascending the brightest portion of the RGB. [ABSTRACT FROM AUTHOR]

Context. The abundance inhomogeneities of light elements observed in globular clusters (GCs), and notably the ubiquitous Na-O anti-correlation, are generally interpreted as evidence that GCs comprise several generations of stars. There is an on-going debate as to the nature of the stars, which produce the inhomogeneous elements, and investigating the behavior of several elements is a way to shed new light on this problem. Aims. We aim at investigating the Li and Na content of the GC M4, that is known to have a well defined Na-O anti-correlation. Methods. We obtained moderate resolution (R = 17000-18 700) spectra for 91 main sequence (MS)/sub-giant branch stars of M4 with the Giraffe spectrograph at the FLAMES/VLT ESO facility. Using model atmospheres analysis we measured lithium and sodium abundances. Results. We detect a weak Li-Na anti-correlation among un-evolved MS stars. One star in the sample, # 37934, shows the remarkably high lithium abundance A(Li) = 2.87, compatible with current estimates of the primordial lithium abundance. Conclusions. The shallow slope found for the Li-Na anti-correlation suggests that lithium is produced in parallel to sodium. This evidence, coupled with its sodium-rich nature, suggests that the high lithium abundance of star # 37934 may originate by pollution from a previous generations of stars. The recent detection of a Li-rich dwarf of pollution origin in the globular cluster NGC6397 may also point in this direction. Still, no clear cut evidence is available against a possible preservation of the primordial lithium abundance for star # 37934. [ABSTRACT FROM AUTHOR]

Explosive activity preceding the ~40 ka Campanian Ignimbrite (CI) eruption in the Neapolitan volcanic area, Southern Italy, has long been speculated based on the occurrences of widespread tephra layers, with a Campanian geochemical signature, such as the C-22, X-5, and X-6, preserved in Mediterranean Marine Isotope Stage (MIS) 5 sedimentary records. However, previous studies of pre-CI pyroclastic units occurring in close proximity of the Neapolitan volcanoes, including Campi Flegrei, Somma-Vesuvius, Ischia and Procida islands, did not allow a conclusive identification of the near-source equivalents of these tephra markers. Here we present a comprehensive characterization of four pyroclastic units from the Campanian Plain, comprising major and trace element glass compositions, Sr Nd isotopes and 40Ar/39Ar dating. Our data allowed the identification of the medial equivalents of the MIS 5 tephra markers, including the widespread C-22, X-5, and X-6 tephra, and their assignment to previously undocumented Campi Flegrei activity between 109 and 92 ka. In addition to substantially extending Campi Flegrei explosive activity deeper in time, and thus providing the basis for a revaluation of its history, our findings provide new precise radioisotopic dating to better constrain the chronology of the millennial scale climatic oscillations of the MIS 5c-d in the Mediterranean area and possibly on a larger scale. • X-6, X-5 and C-22 act as fundamental markers for the Mediterranean MIS 5 stratigraphy • This widespread markers, and two additional tephra, originated in Campi Flegrei volcanic area • These add to the history of this volcano five eruptions occurred between 109 and 92 ka • Their high-precision dating allows the timing MIS 5 climatic events to be precisely assessed [ABSTRACT FROM AUTHOR]

The surgical treatment of achalasia, based on Heller's myotomy is the procedure of choice to reduce the sphincterial high pressure zone, either by laparotomy or, most recently, by laparoscopy. What is the right length of the myotomy? Many authors have reported 10–15% postoperative residual dysphagia, due to the incomplete gastric myotomy and not to esophageal pouring. The aim of this study is to experimentally determine the modifications induced by Heller's myotomy and myectomy of the esophago-gastric junction on lower esophageal sphincter (LES) pressure profile, using a computerized manometric system. Myotomy of the esophageal portion of the LES (i.e. without dissection of the gastric fibers) has not modified the parameters considered, while the dissection of gastric fibers for at least 2–3 cm on the anterior gastric wall has created a significant modification of the LES pressure profile. Our observations seem to confirm and more clearly demonstrate the important role played by gastric fibers in sustaining the sphincteric HPZ. Moreover, analysis of our data, showed the need to always perform a complete myotomy. This was objectively shown during the intervention by means of intraoperative manometry, in order to significantly reduce the possibility of a dysphagic relapse, caused by inadequate treatment. [ABSTRACT FROM AUTHOR]

We present an analysis of the density profile in the central region of the Sagittarius dwarf spheroidal galaxy. A strong density enhancement of Sgr stars is observed. The position of the peak of the detected cusp is indistinguishable from the centre of M54. The photometric properties of the cusp are fully compatible with those observed in the nuclei of dwarf elliptical galaxies, indicating that the Sgr dSph would appear as a nucleated galaxy independently of the presence of M54 at its centre. [ABSTRACT FROM AUTHOR]

We derived the distance to the central region of the Sagittarius (Sgr) dwarf spheroidal galaxy from the red giant branch tip. The obtained distance modulus is, corresponding to a heliocentric distance. This estimate is in good agreement with the distance obtained from RR Lyrae (RR Ly) stars of the globular cluster M 54, located in the core of the Sgr galaxy, once the most accurate estimate of the cluster metallicity and the most recent calibration of theversus[Fe/H] relation are adopted. [ABSTRACT FROM AUTHOR]

We present wide-field photometry of the Galactic globular cluster M22 in the B , V and I passbands for more than 186 000 stars. The study is complemented by the photometry in two narrow-band filters centred on Hα and the adjacent continuum, and by infrared J , H and K magnitudes derived from the Two-Micron All-Sky Survey for ∼2000 stars. Profiting from this huge data base, we completely characterized the evolved stellar sequences of the cluster by determining a variety of photometric parameters, including new photometric estimates of the mean metallicity, reddening and distance to the cluster. In particular, from our multiwavelength analysis, we re-examined the long-standing metallicity spread problem in M22. According to our data set, we conclude that most of the observed width of the red giant branch must be due to differential reddening, which amounts to a maximum of , although the presence of a small metallicity spread cannot be completely ruled out. More specifically, the maximum metallicity spread allowed by our data is of the order of Δ[Fe/H] , i.e. not much more than that allowed by the photometric errors. Finally, we identified most of the known variable stars and peculiar objects in our field of view. In particular, we have found additional evidence supporting previous optical identifications of the central star of the planetary nebula IRAS 18333−2357, which is associated with M22. [ABSTRACT FROM AUTHOR]

The microscopic many-body theory of the Nuclear Equation of State is discussed in the framework of the Bethe-Brueckner-Goldstone method. The expansion is extended up to the three hole-line diagrams contribution. Within the same scheme, the hole spectral function is calculated in nuclear matter to assess the relevance of nucleon-nucleon short-range correlations. The calculation is carried out by using several nucleon-nucleon realistic interactions. Results are compared with other approaches based on variational methods and transport theory. Discrepancies appear in the high-energy region, which is sensitive to short-range correlations, and are due to the different many-body treatment more than to the specific NN interaction used. Both nuclear matter Equation of State and spectral function appear to be dominated by two-body correlations. [ABSTRACT FROM AUTHOR]

A time- and angle-resolved photoelectron spectrometer based on an amplified picosecond Nd:glass laser system is described. The kinetic energy of photoemitted electrons, excited by 0.4 ps laser pulses at 264 nm, is measured with a time-of-flight electron energy analyzer. A theoretical model that takes into account the electron drift inside the μ-metal shielded tube as far as the electron analyzer has been introduced to calculate the energy distribution curves of photoelectrons. As a test of the experimental apparatus we present photoemission spectra of cesiated silver excited with 4.7 eV photons. Good agreement between the experimental and the calculated distribution curves of photoemitted electrons has been found. Finally, we have briefly discussed the electronic properties of silver in terms of free electron and d-band transitions, together with Auger processes for photon energies near 4 eV. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The hole spectral function is calculated in nuclear matter to assess the relevance of nucleon–nucleon short range correlations. The calculation is carried out within the Brueckner scheme of many-body theory by using several nucleon–nucleon realistic interactions. Results are compared with other approaches based on variational methods and transport theory. Discrepancies appear in the high energy region, which is sensitive to short range correlations, and are due to the different many-body treatment more than to the specific NN interaction used. Another conclusion is that the momentum dependence of the G-matrix should be taken into account in any self consistent approach. [Copyright &y& Elsevier]

We provide detailed sedimentological, paleontological, and tephrochronological data on a complex sedimentary succession cropping out in the Tyrrhenian coastal area of central Italy, which was deposited in response to sea-level rise during MIS 7, coeval with the Latera phase of activity in the Vulsini Volcanic District. Diffuse intercalations of primary volcanic layers erupted during this phase and their geochronologic and chemostratigraphical characterization based on 40Ar/39Ar dating and EMP analyses, allowed for the identification of three stacked aggradational successions separated by erosive phases and their correlation with the Oxygen isotope record and phases in the relative sea-level curve. The ages of the tephra layers strictly frame the sedimentation in the interval of 253–206 ka, providing independent dating to glacial Termination III and to the three sea-level oscillations during MIS 7e, 7c, and 7a. Moreover, micro- and macrofaunal-based analyses provide information on the paleoenvironments and bathymetry during the highstands, which complement the geomorphological analysis reconstructing the inner edges of the corresponding marine terraces, allowing us to assess precise maximum sea level reached during MIS 7e and MIS 7a. The results of this multidisciplinary study enable us to establish in great detail the chronology, dynamics, relative amplitude, and effects of the sea-level fluctuations in the Tyrrhenian Sea during the whole MIS 7, providing independent, precise geochronological constraints for this period. • We provide 40Ar/39Ar age constraints on a MIS 7 aggradational succession. • We reconstruct the MIS 7d and MIS 7a marine terraces. • We provide independent age constrains to sea-level rise during MIS 7d, 7c and 7a. • We provide 40Ar/39Ar age constrains to glacial termination III at the onset of MIS 7. • We provide estimation of relative sea-level amplitude during MIS 7d, 7c and 7d. [ABSTRACT FROM AUTHOR]

It has recently been suggested that the peculiar cluster Pal 1 is associated to the Canis Major dwarf galaxy, which existence is still at the center of a debate. Our first measurement of the cluster's chemical abundance ratios allows us to examine this association and to advance further in the clarification of Pal 1 possible origin. [ABSTRACT FROM AUTHOR]

By using high-resolution spectra acquired with FLAMES-GIRAFFE at the ESO/VLT, we measured the radial and rotational velocities of 115 stars in the Galactic globular cluster M 55. After field decontamination based on the radial velocity values, the final sample of member stars is composed of 32 blue straggler stars (BSSs) and 76 reference stars populating the red giant and horizontal branches of the cluster. In agreement with previous findings, the totality of red giant branch stars has negligible rotation (<10 km s−1) and horizontal branch stars have rotational velocities of 40 km s−1 at most. In contrast, the BSS rotational velocity distribution shows a long tail extending up to ~200 km s−1, with 15 BSSs (out of 32), spinning faster than 40 km s−1. By defining the threshold for fast rotating BSSs at 40 km s−1, this sets the percentage of these stars at 47 ±14%. Such a large value has never been found before in any globular clusters. It is roughly comparable to that measured in other loose systems (ω Centauri, M 4, and NGC 3201) and significantly larger than that observed in high-density clusters (as 47 Tucanae, NGC 6397, NGC 6752, and M 30). This evidence supports a scenario whereby recent BSS formation is occurring in low-density environments. We also find that the BSS rotational velocity tends to decrease for decreasing luminosity, as found for another loose cluster of the sample, namely, NGC 3201. [ABSTRACT FROM AUTHOR]

Introduction During the Eye Movement Desensitization and Reprocessing (EMDR) changes of brain electrical activity was recently demonstrated in victims of psychological traumas. Objectives Thirty-one victims of psychological traumas were investigated at the first EMDR session (t0) and at the last one performed after processing the index trauma (t1). Aims To investigate differences in EEG source activity and EEG source functional connectivity (EEG-SFC) in eyes closed condition before the beginning of t0 and t1 EMDR therapy session. Methods Electrical source activity was computed by eLORETA from a 37-channel EEG. EEG-SFC analysis was based on the lagged phase synchronization (LPS), derived by a two-step eLORETA procedure: dimensionality reduction of inverse matrix from 6239 voxels to 28 regions of interest (ROIs); LPS indices computation, for each spectrum band, in all possible ROI pairs. Results Resting-state EEG source activity resulted in a low frequency increase of posterior cingulate cortex and a high frequency (beta2 and gamma) decrease in right prefrontal and parietal cortex between t0 and t1. Significant enhancements of EEG-SFC were detected in t1 respect to t0 between ROI pairs of theta band right temporo-parahippocampal regions and alpha band fronto-parietal regions. Conclusions Significant modifications of resting-state electrical brain activity were present after EMDR therapy. These findings suggest that the elaboration of psychological traumas induced by EMDR produces, in a resting-state condition, an enhancement of activity and functional connectivity of cerebral sources involved in cognitive control and emotional processing. [ABSTRACT FROM AUTHOR]

Volcanic ashes can threaten the human respiratory system through inhalation. In this study we investigated the physical and chemical characteristics of volcanic ashes from the Pomici di Avellino (PdA) eruption, an Early Bronze Age (ca. 3.9 ka) Plinian event from Somma-Vesuvius volcano, southern Italy, whose wide dispersal affected most of the Italian peninsula. In particular, we analysed particle size, shape, composition, and surface reactivity of samples from both proximal and distal locations. Our results indicate that some tephra layers north of Rome have a phonolitic composition and match that of PdA eruption; they reach grain-sizes <2 μm (∼13.5%), thus having the potential to enter the deep respiratory system. Furthermore, the reactivity in free radical generation makes these products potentially able to cause oxidative stress within cells. While commonly no volcanic hazard assessment is made in areas far from active volcanoes, this study highlights that fine ashes from future similar large eruptions, producing high amount of highly fragmented material, can pose a health hazard even in remote, non-volcanic areas, hundreds of km away from the vent, suggesting that further studies on ash toxicity (e.g., in vitro toxicity studies) are required. [Display omitted] • New compositional data on tephra layers from Mezzano and Vico lakes are provided. • Ashes from Mezzano and Vico lakes are ascribable to the PdA eruption. • Grain-size analyses show that PdA ashes are potentially inhalable in distal areas. • PdA ashes can generate hydroxyl radicals and release iron. • The new data can help assessing health concerns from future Somma-Vesuvius eruptions. [ABSTRACT FROM AUTHOR]

We report on a multiwavelength observational campaign which followed the Earth's transit on the Sun as seen from Jupiter on 2014 January 2014. Simultaneous observations of Jupiter's moons Europa and Ganymede obtained with high accuracy radial velocity planetary searcher (HARPS) from La Silla, Chile and HARPS-N from La Palma, Canary Islands were performed to measure the Rossiter-McLaughlin effect due to the Earth's passage using the same technique successfully adopted for the 2012 Venus Transit. The expected modulation in radial velocities was of ≈20 cm s-1 but an anomalous drift as large as ≈38 ms-1, i.e. more than two orders of magnitude higher and opposite in sign, was detected instead. The consistent behaviour of the two spectrographs rules out instrumental origin of the radial velocity drift and Birmingham Solar Oscillations Network observations rule out the possible dependence on the Sun's magnetic activity. We suggest that this anomaly is produced by the opposition surge on Europa's icy surface, which amplifies the intensity of the solar radiation from a portion of the solar surface centred around the crossing Earth which can then be observed as a sort of inverse Rossiter-McLaughlin effect. in fact, a simplified model of this effect can explain in detail most features of the observed radial velocity anomalies, namely the extensions before and after the transit, the small differences between the two observatories and the presence of a secondary peak closer to Earth passage. This phenomenon, observed here for the first time, should be observed every time similar Earth alignments occur with rocky bodies without atmospheres. We predict that it should be observed again during the next conjunction of Earth and Jupiter in 2026. [ABSTRACT FROM AUTHOR]

NGC 362 is a non-common Type II Galactic globular cluster, showing a complex pseudo two-colour diagram or 'chromosome map'. The clear separation of its stellar populations in the colour–magnitude diagram and the distribution of the giant stars in the chromosome map strongly suggests that NGC 362 could host stars with both cluster-nominal, as well as enhanced heavy-element abundances, and one of them could be iron. However, despite previous spectroscopic observations of NGC 362, no such iron variation has been detected. Our main goal is to confirm or disprove this result by searching for any internal variation of [Fe/H], which would give us insight into the formation and evolution of this interesting globular cluster. In this paper, we present the abundance analysis for a sample of 11 red giant branch members based on high-resolution and high S/N spectra obtained with the MIKE echelle spectrograph mounted at the Magellan-Clay telescope. HST and GAIA photometry and astrometry has been used to determine atmospheric parameters and membership. We obtained T eff, log(g), and vt for our target stars and measured the mean iron content of the sample and its dispersion with three different methods, which lead to [Fe/H]1 = −1.10 ± 0.02, [Fe/H]2 = −1.09 ± 0.01, and [Fe/H]3 = −1.10 ± 0.01, while the internal dispersion turned out to be |$\sigma _{[\text{Fe/H}]_1}$|  = 0.06 ± 0.01, |$\sigma _{[\text{Fe/H}]_2}$|  = 0.03 ± 0.01, and |$\sigma _{[\text{Fe/H}]_3}$|  = 0.05 ± 0.01, respectively. The error analysis gives an internal dispersion due to observational error of 0.05 dex. Comparing the observed dispersion with the internal errors, we conclude that NGC 362 does not show any trace of an internal iron spread. [ABSTRACT FROM AUTHOR]

A procedure is discussed that searches for the best description of the eigenstates of a Hamiltonian of a finite quantum many-body system in terms of a selected set of physically relevant configurations. The procedure resorts to iterative sequences of diagonalizations in spaces of very reduced size. Each diagonalization provides an energy-based importance measure that governs the selection of the configurations to be included in the states. The procedure is strictly variational and preserves the symmetries of the Hamiltonian throughout the iterative process. We report on some test applications to the Na8 metal cluster. A series of calculations is performed on a Hartree-Fock basis for a number of orbitals ranging from 5 to 20. In the case of 5 (10) orbitals, we compare the low-lying spectra generated with our procedure to complete (truncated) configuration interaction calculations. The procedure accurately reproduces the results in the complete space. In the most complex cases of 15 and 20 orbitals (the latter involving a many-particle space of 1011 states), we construct the ground state and study its structure. The analysis highlights the efficiency of the method in generating the most appropriate model space for the description of individual eigenstates of the Hamiltonian. [ABSTRACT FROM AUTHOR]

One of the most relevant aspects of friction stir welding is the possibility to weld different materials. In the present paper, the authors present an improved continuum finite element model for the simulation of friction stir welding processes aimed to obtain T joints, made of a stringer in AA7175-T73511 and of a skin in AA2024-T4. The model, taking into account the thermomechanical behaviours of the two different materials, is utilised to study the occurring material flow and residual stress state. Numerical results are compared with experimental observations: the model is able to predict the material flow, obtaining important information on the joint failure mode. [ABSTRACT FROM AUTHOR]

We report on the detection of main-sequence stars belonging to the recently identified Canis Major (CMa) galaxy in a field located atfrom the centre of the stellar system. With main-sequence fitting we obtain a distance modulusto the dwarf, corresponding to a distance of, in full agreement with previous estimates based on the photometric parallax of M-giants. From the comparison with theoretical isochrones, we constrain the age of the main population of the CMa system in the range∼4–10 Gyr. A blue plume of likely younger stars (age<1–2 Gyr) is also identified. The available colour–magnitude diagrams of open clusters that may be projected on to the main body of CMa are also briefly analysed. The position, distance and stellar population of the old open clusters Arp-Madore 2 and Tombaugh 2 strongly suggest that they are physically associated with the CMa galaxy. Using our own photometry and data from the Two-Micron All-Sky Survey and the Guide Star Catalogue 2.2 we demonstrate that the claim by Momany et al. that the CMa overdensity is entirely due to the Galactic warp is not supported by the existing observations, once all the available pieces of information are taken into account. It is shown that the CMa overdensity clearly emerges at a heliocentric distance of∼8 kpc above any overdensity possibly produced by the Galactic warp. [ABSTRACT FROM AUTHOR]

Globular Clusters (GCs) are now well known to almost universally show multiple populations (MPs). The HST UV Legacy Survey of a large number of Galactic GCs in UV filters optimized to explore MPs finds that a small fraction of GCs, termed Type II, also display more complex, anomalous behaviour. Several well-studied Type II GCs show intrinsic Fe abundance variations, suggesting that the other, less well-studied, Type II GCs should also exhibit similar behaviour. Our aim is to perform the first detailed metallicity analysis of NGC 1261, an intermediate mass Type II GC, in order to determine if this object shows an intrinsic Fe variation. We determined the Fe abundance in eight red giant members using Magellan-MIKE and UVES-FLAMES high-resolution, high S/N spectroscopy. The full range of [Fe/H] for the entire sample from the spectra is from −1.05 to −1.43 dex with an observed spread σobs = 0.133 dex. Compared with the total internal error of σtot = 0.06, this indicates a significant intrinsic metallicity spread of σint = 0.119 dex. We found a very similar variation in [Fe/H] using an independent method to derive the atmospheric parameters based on near-IR photometry. More importantly, the mean metallicity of the five presumed normal metallicity stars is −1.37 ± 0.02, while that of the three presumed anomalous/high metallicity stars is −1.18 ± 0.09. This difference is significant at the ∼2.4σ level. We find indications from existing data of other Type II GCs that several of them presumed to have real metallicity spreads may in fact possess none. The minimum mass required for a GC to acquire an intrinsic Fe spread appears to be ∼105 M ⊙. We find no strong correlation between mass and metallicity variation for Type II GCs. The metallicity spread is also independent of the fraction of anomalous stars within the Type II GCs and of GC origin. [ABSTRACT FROM AUTHOR]

An apparatus allowing continuous acquisition of thickness measurements during electropolishing of superconducting cavities is described. The instrument is based on the ultrasound thickness measurement technique and allows the connection of up to six probes. The apparatus has been employed to monitor the surface treatment of PIP-II low beta single cell prototypes developed and manufactured by LASA-INFN and specifically to measure surface removal at different points of interest on the cavity surface. The apparatus facilitated the development and optimization of electropolishing parameters for incorporation into the cavity manufacturing process. [ABSTRACT FROM AUTHOR]

We present an update on the sample of soft gamma-ray selected giant radio galaxies (GRGs) extracted from INTEGRAL/IBIS and Swift /BAT surveys; it includes eight new sources and one candidate object. In the new sample, all but one source display FR II radio morphologies; the only exception is B21144+35B, which is an FR I. The objects belong to both type 1 and type 2 active galactic nucleus (AGN) optical classes and have redshifts in the range 0.06–0.35, while the radio sizes span from 0.7 to 1 Mpc. In this study, we present for the first time two objects that were never discussed as GRGs before and propose a new candidate GRG. We confirm the correlation between the X-ray luminosity and the radio core luminosity found for other soft gamma-ray selected GRGs and expected for AGNs powered by efficient accretion. We also corroborate previous results that indicate that the luminosity of the radio lobes is relatively low compared with the nuclear X-ray emission. This supports the idea that the nucleus of these GRGs is now more powerful than in the past, consistent with a restarting activity scenario. [ABSTRACT FROM AUTHOR]

We exploit a combination of high-resolution Hubble Space Telescope and wide-field ESO-VLT observations to study the slope of the global mass function (α G ) and its radial variation (α(r)) in the two dense, massive and post core-collapse globular clusters M15 and M30. The available data set samples the clusters' main sequence down to ∼0.2 M⊙ and the photometric completeness allows the study of the mass function between 0.40 M⊙ and 0.75 M⊙ from the central regions out to their tidal radii. We find that both clusters show a very similar variation in α(r) as a function of clustercentric distance. They both exhibit a very steep variation in α(r) in the central regions, which then attains almost constant values in the outskirts. Such a behaviour can be interpreted as the result of long-term dynamical evolution of the systems driven by mass-segregation and mass-loss processes. We compare these results with a set of direct N -body simulations and find that they are only able to reproduce the observed values of α(r) and α G at dynamical ages (t / t rh) significantly larger than those derived from the observed properties of both clusters. We investigate possible physical mechanisms responsible for such a discrepancy and argue that both clusters might be born with a non-standard (flatter/bottom-lighter) initial mass function. [ABSTRACT FROM AUTHOR]

The Gaia -ESO Survey (GES) observed many open clusters as part of its programme to spectroscopically characterize the various Milky Way populations. GES spectroscopy and Gaia astrometry from its second data release are used here to assign membership probabilities to targets towards 32 open clusters with ages from 1 to 3800 Myr, based on maximum likelihood modelling of the 3D kinematics of the cluster and field populations. From a parent catalogue of 14 398 individual targets, 5032 stars with uniformly determined 3D velocities, T eff, log  g , and chemistry are assigned cluster membership with probability >0.9, and with an average probability of 0.991. The robustness of the membership probabilities is demonstrated using independent membership criteria (lithium and parallax) in two of the youngest clusters. The addition of radial velocities improves membership discrimination over proper motion selection alone, especially in more distant clusters. The kinematically selected nature of the membership lists, independent of photometry and chemistry, makes the catalogue a valuable resource for testing stellar evolutionary models and investigating the time evolution of various parameters. [ABSTRACT FROM AUTHOR]

Context. Extremely metal-poor stars are keys to understand the early evolution of our Galaxy. The ESO large programme TOPoS has been tailored to analyse a new set of metal-poor turn-off stars, whereas most of the previously known extremely metal-poor stars are giant stars. Aims. Sixty five turn-off stars (preselected from SDSS spectra) have been observed with the X-shooter spectrograph at the ESO VLT Unit Telescope 2, to derive accurate and detailed abundances of magnesium, silicon, calcium, iron, strontium and barium. Methods. We analysed medium-resolution spectra (R ≃ 10 000) obtained with the ESO X-shooter spectrograph and computed the abundances of several α and neutron-capture elements using standard one-dimensional local thermodynamic equilibrium (1D LTE) model atmospheres. Results. Our results confirms the super-solar [Mg/Fe] and [Ca/Fe] ratios in metal-poor turn-off stars as observed in metal-poor giant stars. We found a significant spread of the [α/Fe] ratios with several stars showing subsolar [Ca/Fe] ratios. We could measure the abundance of strontium in 12 stars of the sample, leading to abundance ratios [Sr/Fe] around the Solar value. We detected barium in two stars of the sample. One of the stars (SDSS J114424−004658) shows both very high [Ba/Fe] and [Sr/Fe] abundance ratios (>1 dex). [ABSTRACT FROM AUTHOR]

We present iron, magnesium, calcium, and titanium abundances for 235 stars in the central region of the Sagittarius dwarf spheroidal galaxy (within 9:0' ≃ 70 pc from the centre) from medium-resolution Keck/Deep Imaging Multi-Object Spectrograph spectra. All the considered stars belong to the massive globular cluster M 54 or to the central nucleus of the galaxy (Sgr, N). In particular we provide abundances for 109 stars with [Fe/H] ≥ -1.0, more than doubling the available sample of spectroscopic metallicity and α-elements abundance estimates for Sgr dSph stars in this metallicity regime.We find for the first time a metallicity gradient in the Sgr,N population, whose peak iron abundance goes from [Fe/H] = -0:38 for R ≤ 2:5' to [Fe/H] = -0:57 for 5:0 < R ≤ 9.0'. On the other hand, the trends of [Mg/Fe], [Ca/Fe], and [Ti/Fe] with [Fe/H] are the same over the entire region explored by our study.We reproduce the observed chemical patterns of the Sagittarius dwarf spheroidal as a whole with a chemical evolution model which implies that a high mass progenitor (MDM = 6 × 1010 M☉) and a significant event of mass-stripping occurred a few Gyr ago, presumably starting at the first peri-Galactic passage after infall. [ABSTRACT FROM AUTHOR]

Context. Due to their volatile nature, when sulphur and zinc are observed in external galaxies, their determined abundances represent the gas-phase abundances in the interstellar medium. This implies that they can be used as tracers of the chemical enrichment of matter in the Universe at high redshift. Comparable observations in stars are more difficult and, until recently, plagued by small number statistics. Aims. We wish to exploit the Gaia-ESO Survey (GES) data to study the behaviour of sulphur and zinc abundances of a large number of Galactic stars, in a homogeneous way. Methods. By using the UVES spectra of the GES sample, we are able to assemble a sample of 1301 Galactic stars, including stars in open and globular clusters in which both sulphur and zinc were measured. Results. We confirm the results from the literature that sulphur behaves as an α-element. We find a large scatter in [Zn/Fe] ratios among giant stars around solar metallicity. The lower ratios are observed in giant stars at Galactocentric distances less than 7.5 kpc. No such effect is observed among dwarf stars, since they do not extend to that radius. Conclusions. Given the sample selection, giants and dwarfs are observed at different Galactic locations, and it is plausible, and compatible with simple calculations, that Zn-poor giants trace a younger population more polluted by SN Ia yields. It is necessary to extend observations in order to observe both giants and dwarfs at the same Galactic location. Further theoretical work on the evolution of zinc is also necessary. [ABSTRACT FROM AUTHOR]

We take advantage of the Gaia-ESO Survey iDR4 bulge data to search for abundance anomalies that could shed light on the composite nature of the MilkyWay bulge. The α-element (Mg, Si, and whenever available, Ca) abundances, and their trends with Fe abundances have been analysed for a total of 776 bulge stars. In addition, the aluminum abundances and their ratio to Fe and Mg have also been examined. Our analysis reveals the existence of low-α element abundance stars with respect to the standard bulge sequence in the [α=Fe] versus [Fe=H] plane. Eighteen objects present deviations in [α=Fe] ranging from 2.1 to 5.3ρ with respect to the median standard value. Those stars do not show Mg-Al anti-correlation patterns. Incidentally, this sign of the existence of multiple stellar populations is reported firmly for the first time for the bulge globular cluster NGC 6522. The identified low-α abundance stars have chemical patterns that are compatible with those of the thin disc. Their link with massive dwarf galaxies accretion seems unlikely, as larger deviations in α abundance and Al would be expected. The vision of a bulge composite nature and a complex formation process is reinforced by our results. The approach used, which is a multi-method and model-driven analysis of high resolution data, seems crucial to reveal this complexity. [ABSTRACT FROM AUTHOR]

Context. The stellar abundances observed in globular clusters show complex structures, currently not yet understood. Aims. The aim of this work is to investigate the relations between the abundances of different elements in the globular cluster M 4, selected for its uniform deficiency of iron, to explore the best models explaining the pattern of these observed abundances. Moreover, in turnoff stars, the abundances of the elements are not suspected to be affected by internal mixing. Methods. In M 4, using low and moderate resolution spectra obtained for 91 turnoff (and subgiant) stars with the ESO FLAMES-Giraffe spectrograph, we have extended previous measurements of abundances (of Li, C and Na) to other elements (C, Si, Ca, Sr and Ba), using model atmosphere analysis. We have also studied the influence of the choice of the microturbulent velocity. Results. Firstly, the peculiar turnoff star found to be very Li-rich in a previous paper does not show any other abundance anomalies relative to the other turnoff stars in M 4. Secondly, an anti-correlation between C and Na has been detected, the slope being significative at more than 3σ. This relation between C and Na is in perfect agreement with the relation found in giant stars selected below the RGB bump. Thirdly, the strong enrichment of Si and of the neutron-capture elements Sr and Ba, already observed in the giants in M 4, is confirmed. Finally, the relations between Li, C, Na, Sr and Ba constrain the enrichment processes of the observed stars. Conclusions. The abundances of the elements in the turnoff stars appear to be compatible with production processes by massive AGBs, but are also compatible with the production of second generation elements (like Na) and low Li produced by, for example, fast rotating massive stars. [ABSTRACT FROM AUTHOR]

Starting from a realistic constituent quark model for the nucleon-nucleon interaction, we derive the equation of state (EOS) of nuclear matter within the Bethe-Brueckner-Goldstone approach up to the three-hole-line level, without the need to introduce three-nucleon forces. To estimate the uncertainty of the calculations both the gap and the continuous choices for the single-particle potential are considered and compared. The resultant EOS is compatible with the phenomenological analysis of the saturation point, the incompressibility, the symmetry energy at a low density, and its slope at saturation, together with the high-density pressure extracted from flow data on heavy-ion collisions. Although the symmetry energy is appreciably higher in the gap choice in the high-density region, the maximum neutron star masses derived from the continuous-choice EOS and the gap-choice EOS are similar and close to two solar masses, which is again compatible with recent observational data. A comparison with other microscopic equations of state is presented and discussed. [ABSTRACT FROM AUTHOR]

Context. In the course of the Turn Off Primordial Stars (TOPoS) survey, aimed at discovering the lowest metallicity stars, we have found several carbon-enhanced metal-poor (CEMP) stars. These stars are very common among the stars of extremely low metallicity and provide important clues to the star formation processes. We here present our analysis of six CEMP stars. Aims. We want to provide the most complete chemical inventory for these six stars in order to constrain the nucleosynthesis processes responsible for the abundance patterns. Methods. We analyse both X-Shooter and UVES spectra acquired at the VLT. We used a traditional abundance analysis based on OSMARCS 1D local thermodynamic equilibrium (LTE) model atmospheres and the turbospectrum line formation code. Results. Calcium and carbon are the only elements that can be measured in all six stars. The range is -5.0 ≤ [Ca/H] < -2.1 and 7.12 ≤ A(C) ≤ 8.65. For star SDSS J1742+2531 we were able to detect three Fe i lines from which we deduced [Fe/H] = -4.80, from four Ca II lines we derived [Ca/H] = -4.56, and from synthesis of the G-band we derived A(C) = 7.26. For SDSS J1035+0641 we were not able to detect any iron lines, yet we could place a robust (3σ) upper limit of [Fe/H] < -5.0 and measure the Ca abundance, with [Ca/H] = -5.0, and carbon, A(C) = 6.90, suggesting that this star could be even more metal-poor than SDSS J1742+2531. This makes these two stars the seventh and eighth stars known so far with [Fe/H] < -4.5, usually termed ultra-iron-poor (UIP) stars. No lithium is detected in the spectrum of SDSS J1742+2531 or SDSS J1035+0641, which implies a robust upper limit of A(Li) < 1.8 for both stars. Conclusions. Our measured carbon abundances confirm the bimodal distribution of carbon in CEMP stars, identifying a high-carbon band and a low-carbon band. We propose an interpretation of this bimodality according to which the stars on the high-carbon band are the result of mass transfer from an AGB companion, while the stars on the low-carbon band are genuine fossil records of a gas cloud that has also been enriched by a faint supernova (SN) providing carbon and the lighter elements. The abundance pattern of the UIP stars shows a large star-to-star scatter in the [X/Ca] ratios for all elements up to aluminium (up to 1 dex), but this scatter drops for heavier elements and is at most of the order of a factor of two. We propose that this can be explained if these stars are formed from gas that has been chemically enriched by several SNe, that produce the roughly constant [X/Ca] ratios for the heavier elements, and in some cases the gas has also been polluted by the ejecta of a faint SN that contributes the lighter elements in variable amounts. The absence of lithium in four of the five known unevolved UIP stars can be explained by a dominant role of fragmentation in the formation of these stars. This would result either in a destruction of lithium in the pre-main-sequence phase, through rotational mixing or to a lack of late accretion from a reservoir of fresh gas. The phenomenon should have varying degrees of efficiency. [ABSTRACT FROM AUTHOR]

Context. The severe crowding towards the Galactic plane suggests that the census of nearby stars in that direction may be incomplete. Recently, Scholz reported a new M9 object at an estimated distance d ≃ 7 pc (WISE J072003.20-084651.2; hereafter WISE?J0720) at Galactic latitude b = 2.3°. Aims. Our goals are to determine the physical characteristics of WISE?J0720, its kinematic properties, and to address the question of whether it is a binary object, as was suggested in the discovery paper. Methods. Optical and infrared spectroscopy from the Southern African Large Telescope and Magellan, respectively, and spectral energy distribution fitting were used to determine the spectral type of WISE J0720. The measured radial velocity, proper motion, and parallax yielded its Galactic velocities. We also investigated if WISE J0720 may show X-ray activity based on archival data. Results. Our spectra are consistent with spectral type L0±1. We find no evidence for binarity, apart from a minor 2s level difference in the radial velocities taken at two different epochs. The spatial velocity of WISE J0720 does not connect it to any known moving group; instead, it places the object with high probability in the old thin disk or in the thick disk. The spectral energy distribution fit hints at excess in the 12 μm and 22 μm WISE bands which may be due to a redder companion, but the same excess is visible in other late-type objects, and it more likely implies a shortcoming of the models (e.g., problems with the effective wavelengths of the filters for these extremely cool objects, etc.) rather than a disk or redder companion. The optical spectrum shows some Ha emission, indicative of stellar activity. Archival X-ray observations yield no detection. Conclusions. WISE J0720 is a new member of the solar neighborhood, the third nearest L dwarf. Our data do not support the hypothesis of its binary nature. [ABSTRACT FROM AUTHOR]

Recently, an increasing number of studies were devoted to measure the abundances of neutron-capture elements heavier than iron in stars belonging to Galactic Open Clusters (OCs). OCs span a sizeable range in metallicity (−0.6 ≤ [Fe/H] ≤ +0.4), and they show abundances of light elements similar to disc stars of the same age. A different pattern is observed for heavy elements. A large scatter is observed for Ba, with most OCs showing [Ba/Fe] and [Ba/La] overabundant with respect to the Sun. The origin of this overabundance is not clearly understood. With the goal of providing new observational insights, we determined radial velocities, atmospheric parameters and chemical composition of 27 giant stars members of five OCs: Cr 110, Cr 261, NGC 2477, NGC 2506 and NGC 5822. We used high-resolution spectra obtained with the UVES spectrograph at European Southern Observatory Paranal. We perform a detailed spectroscopic analysis of these stars to measure the abundance of up to 22 elements per star. We study the dependence of element abundance on metallicity and age with unprecedented detail, complementing our analysis with data culled from the literature. We confirm the trend of Ba overabundance in OCs, and show its large dispersion for clusters younger than ∼4 Gyr. Finally, the implications of our results for stellar nucleosynthesis are discussed. We show in this work that the Ba enrichment compared to other neutron-capture elements in OCs cannot be explained by the contributions from the slow neutron-capture process and the rapid neutron-capture process. Instead, we argue that this anomalous signature can be explained by assuming an additional contribution by the intermediate neutron-capture process. [ABSTRACT FROM AUTHOR]

We present the design study of an innovative scheme to generate high repetition rate (multi-MHz-class) THz radiation pulses by using an Energy Recovered Super Conducting Linac operating in Continuous Wave mode driving a Free-Electron Laser Oscillator. The FEL performance is illustrated for one and two color operation. Start-to-end simulations are presented to assess the capability of this scheme for typical values of wavelengths of interest in the 10– 50 μ m (6–30 THz) range. [ABSTRACT FROM AUTHOR]

We report on a chemical-abundance analysis of two very metal-poor horizontal-branch stars in the Milky Way halo: CS 22186-005 ([Fe/H] = -2.70) and CS 30344-033 ([Fe/H] = -2.90). The analysis is based on high-resolution spectra obtained at ESO, with the spectrographs HARPS at the 3.6m telescope, and UVES at the VLT.We adopted one-dimensional, plane-parallel model atmospheres assuming local thermodynamic equilibrium. We derived elemental abundances for 13 elements for CS 22186-005 and 14 elements for CS 30344-033. This study is the first abundance analysis of CS 30344-033. CS 22186-005 has been analyzed previously, but we report here the first measurement of nickel (Ni; Z = 28) for this star, based on twenty-two Ni i lines ([Ni/Fe] = -0.21 ± 0.02); the measurement is significantly below the mean found for most metal-poor stars. Differences of up to 0.5 dex in [Ni/Fe] ratios were determined by different authors for the same type of stars in the literature, which means that it is not yet possible to conclude that there is a real intrinsic scatter in the [Ni/Fe] ratios. For the other elements for which we obtained estimates, the abundance patterns in these two stars match the Galactic trends defined by giant and turnoff stars well. This confirms the value of horizontal-branch stars as tracers of the chemical properties of stellar populations in the Galaxy. Our radial velocities measurements for CS 22186-005 differ from previously published measurements by more than the expected statistical errors. More measurements of the radial velocity of this star are encouraged to confirm or refute its radial velocity variability. [ABSTRACT FROM AUTHOR]

The cosmological Li problem is the observed discrepancy between Li abundance (A(Li)) measured in Galactic dwarf, old and metal-poor stars (traditionally assumed to be equal to the initial value A(Li)0), and that predicted by standard big bang nucleosynthesis (BBN) calculations (A(Li)BBN). Here, we attack the Li problem by considering an alternative diagnostic, namely the surface Li abundance of red giant branch stars that in a colour–magnitude diagram populate the region between the completion of the first dredge-up and the red giant branch bump. We obtained high-resolution spectra with the FLAMES facility at the Very Large Telescope for a sample of red giants in the globular cluster M54, belonging to the Sagittarius dwarf galaxy. We obtain A(Li) = 0.93 ± 0.11 dex, translating – after taking into account the dilution due to the dredge-up – to initial abundances (A(Li)0) in the range 2.35–2.29 dex, depending on whether or not atomic diffusion is considered. This is the first measurement of Li in the Sagittarius galaxy and the more distant estimate of A(Li)0 in old stars obtained so far. The A(Li)0 estimated in M54 is lower by ∼0.35 dex than A(Li)BBN, hence incompatible at a level of ∼3σ. Our result shows that this discrepancy is a universal problem concerning both the Milky Way and extragalactic systems. Either modifications of BBN calculations, or a combination of atomic diffusion plus a suitably tuned additional mixing during the main sequence, need to be invoked to solve the discrepancy. [ABSTRACT FROM PUBLISHER]

The measurement of isotopic ratios provides a privileged insight both into nucleosynthesis and into the mechanisms operating in stellar envelopes, such as gravitational settling. In this article, we give a few examples of how isotopic ratios can be determined from high-resolution, high-quality stellar spectra. We consider examples of the lightest elements, H and He, for which the isotopic shifts are very large and easily measurable, and examples of heavier elements for which the determination of isotopic ratios is more difficult. The presence of 6Li in the stellar atmospheres causes a subtle extra depression in the red wing of the 7Li 670.7 nm doublet which can only be detected in spectra of the highest quality. But even with the best spectra, the derived 6Li abundance can only be as good as the synthetic spectra used for their interpretation. It is now known that 3D non-LTE modelling of the lithium spectral line profiles is necessary to account properly for the intrinsic line asymmetry, which is produced by convective flows in the atmospheres of cool stars, and can mimic the presence of 6Li. We also discuss briefly the case of the carbon isotopic ratio in metal-poor stars, and provide a new determination of the nickel isotopic ratios in the solar atmosphere. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Context. The metal-weak tail of the metallicity distribution function (MDF) of the Galactic Halo stars contains crucial information on the formation mode of the first generation of stars. To determine this observationally, it is necessary to observe large numbers of extremely metal-poor stars. Aims. We present here the Turn-Off Primordial Stars survey (TOPoS) that is conducted as an ESO Large Programme at the VLT. This project has four main goals: (i) to understand the formation of low-mass stars in a low-metallicity gas: determine the metal-weak tail of the halo MDF below [M/H] = -3.5; in particular, we aim at determining the critical metallicity, that is the lowest metallicity sufficient for the formation of low-mass stars; (ii) to determine in extremely metal-poor stars the relative abundances of the elements that are the signature of the massive first stars; (iii) to determine the trend of the lithium abundance at the time when the Galaxy formed; and (iv) to derive the fraction of C-enhanced extremely metal-poor stars with respect to normal extremely metal-poor stars. The large number of stars observed in the SDSS provides a good sample of candidate stars at extremely low metallicity. Methods. Candidates with turn-off colours down to magnitude g = 20 were selected from the low-resolution spectra of SDSS by means of an automated procedure. X-Shooter has the potential of performing the necessary follow-up spectroscopy, providing accurate metallicities and abundance ratios for several key elements for these stars. Results. We present here the stellar parameters of the first set of stars. The nineteen stars range in iron abundance between -4.1 and -2.9 dex relative to the Sun. Two stars have a high radial velocity and, according to our estimate of their kinematics, appear to be marginally bound to the Galaxy and are possibly accreted from another galaxy. [ABSTRACT FROM AUTHOR]

Context. The extremely metal-poor stars are the direct descendants of the first generation stars. They carry the chemical signature of the pristine Universe at the time they formed, shortly after the Big Bang. Aims. We aim to derive information about extremely metal-poor stars from their observed spectra. Methods. Four extremely metal-poor stars were selected from the Sloan Digital Sky Survey (SDSS) and observed during the guaranteed observing time of X-shooter. The X-shooter spectra were analysed using an automatic code, MyGIsFOS, which is based on a traditional analysis method. It makes use of a synthetic grid computed from one-dimensional, plane-parallel, hydrostatic model atmospheres. Results. The low metallicity derived from the SDSS spectra is confirmed here. Two kinds of stars are found. Two stars are confirmed to be extremely metal-poor, with no evidence of any enhancement in carbon. The two other stars are strongly enhanced in carbon. We could not derive iron abundance for one of them, while [Ca/H] is below -4.5. Two of the stars are members of the rare population of extremely metal-poor stars low in alpha elements. [ABSTRACT FROM AUTHOR]