Multiple Stellar Populations in Globular Clusters

Globular Clusters (GCs) exhibit star-to-star variations in specific elements (e.g., He, C, N, O, Na, Al) that bare the hallmark of high temperature H burning. These abundance variations can be observed spectroscopically and also photometrically, with the appropriate choice of filters, due to the changing of spectral features within the band pass. This phenomenon is observed in nearly all of the ancient GCs, although, to date, has not been found in any massive cluster younger than 2~Gyr. Many scenarios have been suggested to explain this phenomenon, with most invoking multiple epochs of star-formation within the cluster, however all have failed to reproduce various key observations, in particular when a global view of the GC population is taken. We review the state of current observations, and outline the successes and failures of each of the main proposed models. The traditional idea of using the stellar ejecta from a 1st generation of stars to form a 2nd generation of stars, while conceptually straight forward, has failed to reproduce an increasing number of observational constraints. We conclude that the puzzle of multiple populations remains unsolved, hence alternative theories are needed.Comment: To appear in Annual Reviews of Astronomy and Astrophysics (volume 56). Author's own version. Please see the journal website for the final published version: http://www.annualreviews.org/journal/astr

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

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

Exploring human capital: discrimination factors and group-specific performance in the football industry

The aim of the study is to investigate whether discrimination factors exist within professional football clubs, concerning the management of their human capital, by analysing the correlation between the footballers’ wages and their performance. An analysis was conducted to show that discrimination, based both on nationality and race, can affect the strategies adopted by football club managers and in the professional footballer labour market, where players are considered to be the human capital of football enterprises. The research framework consists of an analysis of the existing literature on discrimination in sports and of a quantitative analysis based on an exploratory approach, where the wage differences among Italian Serie A league footballers are compared to the performance of each group of players (organised by race or nationality). The results of the analysis of data for all Italian Serie A clubs show that discrimination (in pay) exists against Italian and white players. In contrast, when small and big clubs are considered separately, the findings relating to small clubs highlight that foreign and black players face such discrimination. The results suggest that managers of professional football clubs apply a discrimination strategy. In addition, the results provide practical implications on the types of discrimination errors that are committed by the management of big and small football clubs. Big clubs tend to overrate the contributions of foreign and/or black players compared to those of Italian and white players, while small clubs tend to overrate the contributions of Italian and white players compared to those of foreign and black players. To reduce discrimination, clubs have to correlate how much players are paid with their performance. Further research is recommended to identify the impact of wage inequality on the football labour market and on professional team management

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

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&

INDONESIA’S DEFENSE HEALTH PERSPECTIVE

The National Defense System is a systematic and planned concept, structure and organization, fostering the spirit of the universe of the people and nation, to strengthen and defend themselves from various threats, challenges, obstacles and disturbances that break the Indonesian building and network. The concept embodies software that contains the philosophy, purpose, theoretical framework and framework of the concept of national defense, as a soul and heart that moves continuously in the spirit of conscience defending the country. The purpose of this study is to develop a study about the strategic role of defense health as a diversified potential for multifunctional health to guide the national level of resilience. The potential of health in the field of defense with its strategic thinking decomposes the breadth of Indonesia's geographic region, which has distinctive characteristics of health problems based on geomedicine maps. The dynamic stratification of health problems makes geomedicine maps as a measure of defense health policy. The concept proposed in this study is expected to be one of the basic references in forming a defense health study program at Indonesia Defense University. The method, that needs to be developed, is the transformation of the health of Indonesian National Armed Forces (TNI). At this time, it has achieved dynamic values in realizing a broader role, not only in the field of health services and support, but it has begun to expand into the field of research and development (R & D). This development also related to global challenges, where the spread/pandemic of illness becomes an extraordinary homework, especially related to defense health. Defense health is a multiparadigmatic concept with multidisciplinary scientific dimensions and parameters, and various multi-approaches (analysis, synthesis, and solution), based on philosophy and history, build a defense health characteristic that has a scientific perspective that has reliability and validity, so th purpose of this study can be obtained

Globular Cluster Mass Loss in the Context of Multiple Populations

Many scenarios for the origin of the chemical anomalies observed in globular clusters (GCs; i.e., multiple populations) require that GCs were much more massive at birth, up to $10-100\times$, than they are presently. This is invoked in order to have enough material processed through first generation stars in order to form the observed numbers of enriched stars (inferred to be second generation stars in these models). If such mass loss was due to tidal stripping, gas expulsion, or tidal interaction with the birth environment, there should be clear correlations between the fraction of enriched stars and other cluster properties, whereas the observations show a remarkably uniform enriched fraction of $0.68\pm0.07$ (from 33 observed GCs). If interpreted in the heavy mass loss paradigm, this means that all GCs lost the same fraction of their initial mass (between $95-98$\%), regardless of their mass, metallicity, location at birth or subsequent migration, or epoch of formation. This is incompatible with predictions, hence we suggest that GCs were not significantly more massive at birth, and that the fraction of enriched to primordial stars observed in clusters today likely reflects their initial value. If true, this would rule out self-enrichment through nucleosynthesis as a viable solution to the multiple population phenomenon

Mining SDSS in search of Multiple Populations in Globular Clusters

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