Blue Straggler Stars: The Spectacular Population in M80

Using HST-WFPC2 observations in two ultraviolet (UV) filters (F225W and F336W) of the central region of the high density Galactic Globular cluster (GGC) M80 we have identified 305 Blue Straggler Stars (BSS) which represents the largest and most concentrated population of BSS ever observed in a GGC. We also identify the largest, clean sample of evolved BSS yet found. The high stellar density alone cannot explain the BSS, and we suggest that in M80 we are witnessing a transient dynamical state, during which stellar interactions are delaying the core-collapse process leading to an exceptionally large population of collisional-BSS.Comment: 15 pages, 5 figures, Astrophysical Journal Letters, in pres

ROSAT HRI X-ray Observations of the Open Globular Cluster NGC 288

A ROSAT HRI X-ray image was obtained of the open globular cluster NGC 288, which is located near the South Galactic Pole. This is the first deep X-ray image of this system. We detect a Low Luminosity Globular Cluster X-ray source (LLGCX) RXJ005245.0-263449 with an X-ray luminosity of (5.5+-1.4)x10^32 ergs/s (0.1-2.0 keV), which is located very close to the cluster center. There is evidence for X-ray variability on a time scale of <~ 1 day. The presence of this LLGCX in such an open cluster suggests that dense stellar systems with high interaction rates are not needed to form LLGCXs. We also searched for diffuse X-ray emission from NGC 288. Upper limits on the X-ray luminosities are L_X^h < 9.5x10^32 ergs/s (0.52-2.02 keV) and L_X^s < 9.3x10^32 ergs/s (0.11-0.41 keV). These imply upper limits to the diffuse X-ray to optical light ratios in NGC 288 which are lower than the values observed for X-ray faint early-type galaxies. This indicates that the soft X-ray emission in these galaxies is due either to a component which is not present in globular clusters (e.g., interstellar gas, or a stellar component which is not found in low metallicity Population II systems), or to a relatively small number of bright Low Mass X-ray Binaries (LMXBs).Comment: The Astrophysical Journal in press. Minor revisions to improve presentation. 6 pages with 3 embedded Postscript figures in emulateapj.st

Another Faint UV Object Associated with a Globular Cluster X-Ray Source: The Case of M92

The core of the metal poor Galactic Globular Cluster M92 (NGC 6341) has been observed with WFPC2 on the Hubble Space Telescope through visual, blue and mid-UV filters in a program devoted to study the evolved stellar population in a selected sample of Galactic Globular Clusters. In the UV $(m_{255}, m_{255}-U)$ color magnitude diagram we have discovered a faint `UV-dominant' object. This star lies within the error box of a Low Luminosity Globular Cluster X-ray source (LLGCX) recently found in the core of M92. The properties of the UV star discovered in M92 are very similar to those of other UV stars found in the core of some clusters (M13, 47 Tuc, M80, etc)---all of them are brighter in the UV than in the visible and are located in the vicinity of a LLGCX. We suggest that these stars are a new sub-class of cataclysmic variables.Comment: 21 pages, 4 figures. Astrophysical journal in pres

Very Large Telescope Observations of the peculiar globular cluster NGC6712. Discovery of a UV, H-alpha excess star in the core

We present results from multi-band observations in the central region of the cluster NGC6712 with the ESO-Very Large Telescope. Using high resolution images we have identified three UV-excess stars. In particular two of them are within the cluster core, a few arcsec apart: the first object is star "S" which previous studies identified as the best candidate to the optical counterpart to the luminous X-ray source detected in this cluster. The other UV object shows clearcut H-alpha emission and, for this reason, is an additional promising interacting binary candidate (a quiescent LMXB or a CV). The presence of two unrelated interacting binary systems a few arcsec apart in the core of this low-density cluster is somewhat surprising and supports the hypothesis that the (internal) dynamical history of the cluster and/or the (external) interaction with the Galaxy might play a fundamental role in the formation of these peculiar objects.Comment: 15 pages, 3 figures. ApJL in pres

The Luminosity Function of M3

We present a high precision, large sample luminosity function (LF) for the Galactic globular cluster M3. With a combination of ground based and Hubble Space Telescope data we cover the entire radial extent of the cluster. The observed LF is well fit by canonical standard stellar models from the red giant branch (RGB) tip to below the main sequence turnoff point. Specifically, neither the RGB LF-bump nor subgiant branch LF indicate any breakdown in the standard models. On the main sequence we find evidence for a flat initial mass function and for mass segregation due to the dynamical evolution of the cluster.Comment: 18 pages, 13 figures. ApJ, in pres

Na-O Anticorrelation and HB. IV. Detection of He-rich and He-poor stellar populations in the globular cluster NGC 6218

We used the multifiber spectrograph FLAMES on the ESO Very Large Telescope UT2 to derive atmospheric parameters, metallicities and abundances of O and Na for 79 red giant stars in the Galactic globular cluster NGC 6218 (M 12). We analyzed stars in the magnitude range from about 1 mag below the bump to the tip of the Red Giant Branch. The average metallicity we derive is [Fe/H]=-1.31+/-0.004+/-0.028 dex (random and systematic errors, respectively), with a very small star-to-star scatter (rms=0.033 dex), from moderately high-resolution Giraffe spectra. This is the first extensive spectroscopic abundance analysis in this cluster. Our results indicate that NGC 6218 is very homogeneous as far as heavy elements are concerned. On the other hand, light elements involved in the well known proton-capture reactions of H-burning at high temperature, such as O and Na, show large variations, anticorrelated with each other, at all luminosities along the red giant branch. The conclusion is that the Na-O anticorrelation must be established in early times at the cluster formation. We interpret the variation of Na found near the RGB-bump as the effect of two distinct populations having different bump luminosities, as predicted for different He content. To our knowledge, NGC 6218 is the first GC where such a signature has been spectroscopically detected, when combined with consistent and homogeneous data obtained for NGC 6752 to gain in statistical significance.Comment: 15 pages, 10 figures; fig.5 degraded in resolution; tables 2,3,5 available at CDS. Accepted for publication on A&

Preliminary investigation of haematological and biochemical parameters as prognostic markers in dogs with severe inflammation

Nowadays, the search for reliable prognostic markers in dogs with diseases causing severe systemic inflammation is widely issued. In fact, an early diagnosis would allow a better therapeutic management and a direct communication between the clinician and the owner about the patient's outcome. The aim of this study was to evaluate the possible role of basic haematological and biochemical parameters, in addition to inflammatory markers, such as C-Reactive Protein (CRP) and Paraoxonase-1 (PON-1), as prognostic markers in dogs with severe inflammation, regardless of the underlying disease. In this retrospective study, 24 dogs with a definitive diagnosis and a known outcome were enrolled; the presence of systemic clinical signs related to inflammation and the availability of blood smears, haematological and biochemical data were necessary, whereas dogs with the absence of the aforementioned criteria and the diagnosis of neoplasia were excluded. Definitive diagnosis of this study included pyometra (4), pancreatitis (3), pneumonia (3) and other diseases with 2 or less cases (e.g. parvovirosis, cholecystitis). Results obtained after dichotomization of numerical data in two groups (survivors vs non-survivors) were compared to each other using a non-parametric t-test for independent samples (U Mann Whitney test). Although non-regenerative anaemia was the most common haematological finding (58% of the caseload) it hasn’t been correlated with the outcome in this study. Three parameters were statistically related to the outcome: white blood cell (WBC) count (median value in survivors 28,20 vs 15,34 x 10 3/μL; P = 0.033), glucose (median value in survivors 119 vs 96 mg/dL in non survivors; P = 0.031) and urea (median value in survivors 57 vs 31 mg/dL in non survivors; P = 0.028) with higher values in the survivors group. In the present study, CRP and PON-1 lacked difference in terms of statistical significance, median values and data distribution according to the outcome. Further studies on a wider and less heterogeneous caseload in terms of underlying disease and therapeutic management would allow to better define the prognostic value of the evidenced parameters

Learning from failures: Accidents of marine structures on Norwegian continental shelf over 40 years time period

This paper investigates accidents, major accidents and disasters which occurred on the Norwegian Continental Shelf (NCS) over a period of more than 40 years time (1972-2013). An accident investigation based on the system life-cycle was applied on the data provided by the World Offshore Accident Database (WOAD) where the operation (in-service) stage of the lifecycle was found to be the stage with 96% and the installation stage with 4% of accident occurrences. The marine operations linked to both installation and the operation (in-service) stages are identified to be where 13% of accidents had occurred. In terms of structural types, jackets and semi-submersibles are identified with the highest number of accidents, while the highest rate of accidents per marine structure type is linked to the concrete structures where in average 5.5 accidents per each concrete structures were recorded. 1980 was the year with the highest number of fatalities on NCS within 40 years time span with the occurrence of Alexander L. Kielland disaster. There has been a reduction of number of fatalities over the years, but injuries had always been present. It was found that possible correlations can be established among occurrence of accidents and environmental loads for some months. The results and discussions contributes to learning from the 40 years accidents on the NCS with the aim of risk reduction in operation of marine structures. The predictive and preventive maintenance strategy and condition monitoring during operation (in-service) stage for each individual marine structure is promoted. However, the uncertainty is still present and risk can never be reduced to zero..publishedVersionhttps://doi.org/10.1016/j.engfailanal.2020.104487 Available online 06 March 2020 1350-6307/ © 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/)