1,721,160 research outputs found
Mercer 5: A probable new globular cluster in the Galactic bulge
Full text linkWe present a detailed study of a dust-obscured Galactic star cluster Mercer 5 ([MCM2005b] 5) in an extremely crowded field in the Milky Way. Near-infrared (near-IR) photometry from United Kingdom Infrared Digital Sky Surveys (UKIDSS) and the Son of ISAAC on the New Technology Telescope (SofI/NTT), combined with near-IR spectroscopy also from SofI, indicates that it is almost certainly a Galactic globular cluster, located at the edge of the Galactic bulge. The cluster suffers ~9 mag of visual extinction, with strong evidence for an extinction gradient across the cluster. A simulation of the differential reddening in the cluster using empirical data from NGC 6539 (chosen because it had high signal-to-noise ratio data and low field star contamination) as a template mimics the observations extremely well. This simulation and other arguments are used to indicate that the most prominent clump of stars in the colour-magnitude diagrams is a horizontal branch clump. On this basis we conclude that the cluster is at a distance of ~5.5kpc and suffers from visual extinction ranging from ~8.5 to ~12.5 mag. Alternative explanations for its nature, such as a young cluster or an old open cluster, are much less likely, on the grounds of no visible main sequence or stars with IR excesses for the former and location versus lifetime arguments for the latter. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS
The Internal Dynamics of A115 Nearby Cluster of GalaxiesGroups of Galaxies in the Nearby Universe
No full textBased on optical data we propose a dynamycal model for A115. From spatial and radial velocity distributions we find three massive subsclusters that configure a pre-merging scenario. On this basis, we discuss on the origin of the radio emission and its correlation with X-rays
Obscured clusters. II. GLIMPSE-C02 - A new metal rich globular cluster in the Milky Way
Full text linkContext: The estimated total number of Milky Way globulars is 160 ± 20. The question of whether there are any more undiscovered globular clusters in the Milky Way is particularly relevant with advances in near and mid-IR instrumentation.
Aims: This investigation is a part of a long-term project to search the inner Milky Way for hidden star clusters and to study them in detail. GLIMPSE-C02 (G02) is one of these objects, situated near the Galactic plane (l = 14.129 deg, b = -0.644 deg).
Methods: Our analysis is based on SOFI/NTT JHKS imaging and low resolution (R ̃ 1400) spectroscopy of three bright cluster red giants in the K atmospheric window. We derived the metal abundance by analysis of these spectra and from the slope of the RGB.
Results: The cluster is deeply embedded in dust and undergoes a mean reddening of AV ~ 24.8 ± 3 mag. The distance to the object is D = 4.6 ± 0.7 kpc. The metal abundance of G02 is [Fe/H]H96 = -0.33± 0.14 and [Fe/H]CG = -0.16 ± 0.12 using different scales. The best fit to the radial surface brightness profile with a single-mass King's model yields a core radius rc = 0.70 arcmin (0.9 pc), tidal radius rt = 15 arcmin (20 pc), and central concentration c = 1.33.
Conclusions: We demonstrate that G02 is new Milky Way globular cluster, among the most metal rich globular clusters in the Galaxy. The object is physically located at the inner edge of the thin disk and the transition region with the bulge, and also falls in the zone of the “missing” globulars toward the central region of the Milky Way
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The VVV-SkZ Pipeline: How to Get Automatic PSF-Fitting Photometry from the VVV Survey
Full text linkWe present the VVV-SkZ_pipeline, a DAOPHOT-based pipeline created to perform PSF-fitting photometry of the “VISTA Variables in the Vía Láctea” (VVV) ESO Public Survey data. The pipeline avoids repetitive interaction by the user, but still retains all the benefits, power, and accuracy of the DAOPHOT suite. The pipeline provides an astrometrized photometric catalog in the regime where other techniques fail, for example, producing reliable results up to 2 magnitudes brighter than the saturation limit. It also produces deeper and more accurate photometry. These achievements allow the VVV-SkZ_pipeline to produce data well anchored to the selected standard photometric system and allows the study of important stellar phenomena (i.e., tip of the red giant branch stars, red giant branches, horizontal branch morphology, RR Lyrae stars), that may be beyond the reach using other methods of photometric reduction
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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