496 research outputs found

    Carbon and nitrogen abundances of stellar populations in the globular cluster M 2

    Full text link
    We present CH and CN index analysis and C and N abundance calculations based on the low-resolution blue spectra of red giant branch (RGB) stars in the Galactic globular cluster NGC 7089 (M 2). Our main goal is to investigate the C-N anticorrelation for this intermediate metallicity cluster. The data were collected with DOLORES, the multiobject, low-resolution facility at the Telescopio Nazionale Galileo. Spectroscopic data were coupled with UV photometry obtained during the spectroscopic run. We found a considerable star-to-star variation in both A(C) and A(N) at all luminosities for our sample of 35 targets. These abundances appear to be anticorrelated, with a hint of bimodality in the C content for stars with luminosities below the RBG bump (V~15.7), while the range of variations in N abundances is very large and spans almost ~ 2 dex. We find additional C depletion as the stars evolve off the RGB bump, in fairly good agreement with theoretical predictions for metal-poor stars in the course of normal stellar evolution. We isolated two groups with N-rich and N-poor stars and found that N abundance variations correlate with the (U-V) color in the DOLORES color-magnitude diagram (CMD). The V, (U-V) CMD for this cluster shows an additional RGB sequence, located at the red of the main RGB and amounting to a small fraction of the total giant population. We identified two CH stars detected in previous studies in our U, V images. These stars, which are both cluster members, fall on this redder sequence, suggesting that the anomalous RGB should have a peculiar chemical pattern. Unfortunately, no additional spectra were obtained for stars in this previously unknown RGB branch.Comment: 15 pages, 14 figures; accepted for publication in A&

    Changing the University System Management: a study of the Italian scenario

    Get PDF
    Over recent years, the Italian University System has been handling a phase of deep changes, which have had significant impact on its mission and on the way it operates. The most important of these changes have been to the organisation of universities, their recruitment procedures and in terms of improvements to the quality and efficiency of the university system itself. In this perspective, the objective of this research was to carry out a critical analysis of the process of change, with special reference to improving efficiency by making the transition from cash-based accounting to accrual accounting. In order to achieve this objective, the starting point was the legislation of reference that sets out the terms for the move to financial accrual accounting. A comparative analysis was then carried out at an international level, with the purpose of highlighting the strengths and weaknesses identified during the implementation of these new procedures within the public field. This was followed by an analysis of the details of the theory defining the accounting principles to be used in the process of preparing university’s financial statements. Finally, the study identified the main critical points relating to implementation of the new accounting system, offering, at the same time, several thoughts concerning possible subsequent analyses on this topic

    Mining SDSS in search of Multiple Populations in Globular Clusters

    Full text link
    Several recent studies have reported the detection of an anomalous color spread along the red giant branch (RGB) of some globular clusters (GC) that appears only when color indices including a near ultraviolet band (such as Johnson U or Stromgren u) are considered. This anomalous spread in color indexes such as U-B or c_{y} has been shown to correlate with variations in the abundances of light elements such as C, N, O, Na, etc., which, in turn, are generally believed to be associated with subsequent star formation episodes that occurred in the earliest few 10^{8} yr of the cluster's life. Here we use publicly available u, g, r Sloan Digital Sky Survey photometry to search for anomalous u-g spreads in the RGBs of nine Galactic GCs. In seven of them (M 2, M 3, M 5, M 13, M 15, M 92 and M 53), we find evidence of a statistically significant spread in the u-g color, not seen in g-r and not accounted for by observational effects. In the case of M 5, we demonstrate that the observed u-g color spread correlates with the observed abundances of Na, the redder stars being richer in Na than the bluer ones. In all the seven clusters displaying a significant u-g color spread, we find that the stars on the red and blue sides of the RGB, in (g, u-g) color magnitude diagrams, have significantly different radial distributions. In particular, the red stars (generally identified with the second generation of cluster stars, in the current scenario) are always more centrally concentrated than blue stars (generally identified with the first generation) over the range sampled by the data (0.5r_{h} < r < 5r_{h}), in qualitative agreement with the predictions of some recent models of the formation and chemical evolution of GCs. Our results suggest that the difference in the radial distribution between first and second generation stars may be a general characteristic of GCs.Comment: 11 pages, 5 figures, typos adde

    Exploring blockchain in the accounting domain: a bibliometric analysis

    Get PDF
    Purpose: Considering the growing interests in managerial and accounting issues related to blockchain technology (BT), the study aims at identifying the main research venues in this specific field. In particular, the purpose is to understand the spatial and temporal production and distribution of research documents, highlighting the most relevant topics, the most influential authors and research. Design/methodology/approach: This research carries out a bibliometric analysis of 189 research documents in the business, management and accounting areas. Data collection and refining is carried out from the Scopus database. The data analysis is based on a hybrid literature review approach using a descriptive bibliometric method, data analysis visualization (through VOSViewer software) and thematic analysis. Findings: Results indicate that research studies focused on BT and accounting have been growing exponentially over the last three years, with authors who previously focused on generalist themes, and are now facing more specific issues. Through cluster analysis, the authors propose the framework of accounting domain and blockchain technology (ADOB) to systematize and visualize the map of current studies about the BT in the accounting domain. Research limitations/implications: The analysis highlights some aspects less investigated at the first research stage in the field of BT and accounting, such as the growing need of new accounting and control processes to address the practical issues of BT implementation and the need for education and training to stimulate a proper use of BT by accountants and practitioners. Originality/value: This study is the first to adopt a bibliometric and thematic analysis to investigate BT in the accounting domain. The authors provide significant insights that could guide and foster the use of BT for accountants and practitioners, defining future research lines and a research agenda for academic researchers

    The iron dispersion of the globular cluster M 2, revised

    Get PDF
    M 2 has been claimed to posses three distinct stellar components that are enhanced in iron relative to each other. We use equivalent width measurements from 14 red giant branch stars from which Yong et al. detect a \sim0.8 dex wide, trimodal iron distribution to redetermine the metallicity of the cluster. In contrast to Yong et al., which derive atmospheric parameters following only the classical spectroscopic approach, we perform the chemical analysis using three different methods to constrain effective temperatures and surface gravities. When atmospheric parameters are derived spectroscopically, we measure a trimodal metallicity distribution, that well resembles that by Yong et al. We find that the metallicity distribution from Fe II lines strongly differs from the distribution obtained from Fe I features when photometric gravities are adopted. The Fe I distribution mimics the metallicity distribution obtained using spectroscopic parameters, while the Fe II shows the presence of only two stellar groups with metallicity [Fe/H]\simeq-1.5 and -1.1 dex, which are internally homogeneous in iron. This finding, when coupled with the high-resolution photometric evidence, demonstrates that M 2 is composed by a dominant population (\sim99%) homogeneous in iron and a minority component (\sim1%) enriched in iron with respect to the main cluster population

    A chemical trompe-l'\oe{}il: no iron spread in the globular cluster M22

    Get PDF
    We present the analysis of high-resolution spectra obtained with UVES and UVES-FLAMES at the Very Large Telescope of 17 giants in the globular cluster M22, a stellar system suspected to have an intrinsic spread in the iron abundance. We find that when surface gravities are derived spectroscopically (by imposing to obtain the same iron abundance from FeI and FeII lines) the [Fe/H] distribution spans ~0.5 dex, according to previous analyses. However, the gravities obtained in this way correspond to unrealistic low stellar masses (0.1-0.5 Msun) for most of the surveyed giants. Instead, when photometric gravities are adopted, the [FeII/H] distribution shows no evidence of spread at variance with the [FeI/H] distribution. This difference has been recently observed in other clusters and could be due to non-local thermodynamical equilibrium effects driven by over-ionization mechanisms, that mainly affect the neutral species (thus providing lower [FeI/H]) but leave [FeII/H] unaltered. We confirm that the s-process elements show significant star-to-star variations and their abundances appear to be correlated with the difference between [FeI/H] and [FeII/H]. This puzzling finding suggests that the peculiar chemical composition of some cluster stars may be related to effects able to spuriously decrease [FeI/H]. We conclude that M22 is a globular cluster with no evidence of intrinsic iron spread, ruling out that it has retained the supernovae ejecta in its gravitational potential well.Comment: Accepted for publication to ApJ; 33 pages, 10 figures, 6 table

    The double RGB in M 2: C, N, Sr and Ba abundances

    Full text link
    The globular cluster M 2 has a photometrically detected double red giant branch (RGB) sequence. We investigate here the chemical differences between the two RGBs in order to gain insight in the star formation history of this cluster. The low-resolution spectra, covering the blue spectral range, were collected with the MODS spectrograph on the LBT, and analyzed via spectrum synthesis technique. The high quality of the spectra allows us to measure C, N, Ba, and Sr abundances relative to iron for 15 RGB stars distributed along the two sequences. We add to the MODS sample C and N measurements for 35 additional stars belonging to the blue RGB sequence, presented in Lardo et al. (2012). We find a clear separation between the two groups of stars in s-process elements as well as C and N content. Both groups display a C-N anti-correlation and the red RGB stars are on average richer in C and N with respect to the blue RGB. Our results reinforce the suggestion that M2 belongs to the family of globular clusters with complex star formation history, together with Omega Cen, NGC 1851, and M 22.Comment: 11 pages, 8 figures. Accepted for publication in MNRA

    Intangible assets management and digital transformation: evidence from intellectual property rights-intensive industries

    Get PDF
    Purpose: This study aims to investigate the impact of digital technologies for intangible assets management. The authors analyse how technological innovations and regulations of intellectual property affect business models of companies or intellectual property rights (IPR) intensive industries to determine the impact of digital transformation on intangible assets management, highlighting emerging issues and future effects of the digital technology revolution. Design/methodology/approach: The authors use a case study method to answer our research questions. The authors use Soundreef SpA as our case study, a collecting company that develops technology for monitoring, collecting and maximising the earnings of songwriters and music publishers. The authors also elaborate and adopt the framework of the enhanced intellectual capital as the theoretical lens for presenting and analysing our case study, determining how the digital transformation caused business model innovation and more transparent and timely performance measurement in copyright-based companies. Findings: The analysis of Soundreef SpA’s business model allows us to demonstrate how using new technologies drives the performance measurement of copyright holders and improve the collecting societies’ performance, introducing a new key performance indicator. This turning point is made possible by digital transformation and regulatory change. In the IPR industry, copyright holders’ performance has never been calculated, so the distribution of copyright revenues was based on the criteria approved by governance bodies/management. Originality/value: In the study, the authors demonstrate that digital transformation is able to enhance the intellectual capital of IPR-intensive companies introducing new ways to manage intangible assets and to measure performance
    corecore