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Author : Christopher Z. Waters
Publisher :
ISBN 13 :
Total Pages : 326 pages
Book Rating : 4.3/5 (129 download)
Download or read book High Resolution Analysis of Extragalactic Globular Clusters written by Christopher Z. Waters and published by . This book was released on 2007 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ashley Chutter
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (858 download)
Download or read book Elemental Abundance Investigation of Two Candidate Extragalactic Globular Clusters (NGC 5024, NGC 5466). written by Ashley Chutter and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High resolution spectra have been analyzed for two and three stars respectively in the candidate extragalactic globular clusters, NGC 5024 and NGC 5466, with the High-Resolution Spectrograph on the 9.2 m Hobby-Eberly Telescope. The goal of this investigation is to evaluate the proposed extragalactic origins of these two globular clusters. Evidence of a tidal tail in NGC 5466 (Belokurov et al., 2006) and the association of NGC 5024 with the Sagittarius stream (Martinez-Delgado et al., 2004) targeted the clusters as likely remnants of recent accretion events and thus potentially of extragalactic origin. Determination of their chemical abundance patterns could provide unique evidence to either support or dispute these claims. NGC 5024 has been associated with a proposed wrap in the Sagittarius stream which could be supported if the chemistry of NGC 5024 is similar to other clusters associated with the stream. NGC 5466 has the longest tidal tail known, which hints at an origin in a now dispersed dwarf spheroidal galaxy. Additional evidence for these clusters' capture origins has been compiled by Yoon & Lee (2002), demonstrating that these two low metallicity clusters, along with five others, are aligned in a single highly inclined plane in the outer halo. Confirmation that these clusters are remnants of dwarf galaxies would support a Galactic history which includes recent accretion events. Such evidence may bolster the cold dark matter hierarchical clustering scenario, which postulates the presence of a significant amount of substructure in the Milky Way. Unfortunately, at the metallicity of the target clusters ([Fe/H] = -1.9), the chemical distinction between Galactic stars and known dSph stars is not significant. The low [alpha/Fe] of dSph stars seen at higher metallicity is not apparent at [Fe/H] = -1.9 in either Galactic or dSph stars. Aside from a few mild discrepancies, NGC 5024 and NGC 5466 appear chemically similar to the Galactic field stars and globular clusters compiled by Pritzl et al. (2005). A moderate enhancement in the [Ba/Y] ratios relative to the halo field stars is the only positively detected chemical signature that is typically observed in dSph stars. Comparisons with Galactic GCs of similar age, metallicity and horizontal branch morphology (NGC 2298, NGC 6397 and NGC 5897) reveal a few other differences, but these could be attributed to systematic effects in the different analysis techniques. Although NGC 5024 has a similar metallicity to the GC Arp 2 that was stripped from the merging Sagittarius dwarf, neither Arp 2 (Mottini et al., 2008) nor the clusters in this study show any particularly unusual chemical abundance patterns. Thus, no conclusive evidence in support of or in opposition to the target clusters' proposed extragalactic origins has been discovered.
Author : Zachary Grove Jennings
Publisher :
ISBN 13 : 9780355131499
Total Pages : 272 pages
Book Rating : 4.1/5 (314 download)
Download or read book The Photometric Properties of Extragalactic Globular Cluster Systems written by Zachary Grove Jennings and published by . This book was released on 2017 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Globular Clusters (GCs) are powerful tools for understanding the formation of galaxies. GCs are located in the halos of galaxies and, due to their age and density, have borne witness to the major formation events of a galaxy's lifetime. One may study these objects using a wide array of techniques and datasets, including wide-field ground-based imaging, deep space-based imaging, and spectroscopy. All approaches involve tradeoffs, and in this work we consider a variety of ways to study GC systems in imaging data. We examine a wide-field HST/ACS mosaic of the nearby lenticular galaxy NGC 3115, selecting a high-quality GC sample using the superior resolution of the ACS data. We find strong color bimodality in the GC system of NGC 3115 and examine a number of trends in the properties of the GC system. Next, we consider the situation where one is limited to ground-based imaging, where contaminants to the GC population are a major concern. We detail a novel statistical methodology in which we treat the GC population and the contaminant population as a mixture model, and evaluate the model in a Bayesian context. We demonstrate the performance of the model on mock data, and note some areas where current analysis of GC systems may be missing information using traditional selection techniques. We also apply this Bayesian methodology to a subset of SLUGGS survey galaxies with high-quality photometry from either the MegaCam instrument on the Canada France-Hawaii Telescope or the SuprimeCam instrument on the Subaru Telescope. In most cases, the mixture model recovers the GC system well, often finding the traditional bimodality and providing well-calibrated statistical uncertainties for the global parameters of the GC system. Finally, we examine the object NGC 3628 UCD1, a star cluster slightly more massive than the largest GCs. We identify that UCD1 is located in a stellar stream around the galaxy NGC 3628, and therefore is in the process of being accreted. We characterize UCD1 both in wide-field SuprimeCam imaging and in Keck/ESI spectroscopy, and identify a number of interesting parallels between UCD1 and omegaCen, the largest Milky Way GC.
Author : Markus Kissler-Patig
Publisher : Springer Science & Business Media
ISBN 13 : 9783540404729
Total Pages : 382 pages
Book Rating : 4.4/5 (47 download)
Download or read book Extragalactic Globular Cluster Systems written by Markus Kissler-Patig and published by Springer Science & Business Media. This book was released on 2003-07-21 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dramatic progress is a trademark of the recent study of globular cluster systems. Considerations about the formation and evolution compose the first chapter, followed by a chapter on young star clusters. Then come four chapters reviewing the globular cluster system of early-type, late-type and dwarf galaxies, as well as of groups of galaxies. One chapter is dedicated to stellar population models and their applications to the field. Finally a chapter reviews the kinematics of galaxies derived from globular cluster systems and another their role in the context of galaxy formation and evolution studies. As a whole, the book gives an up-to-date view of the field at the beginning of the new decade, which will without doubt again bring significant progress in our understanding of globular cluster systems and galaxy formation and evolution.
Author : Tom Richtler
Publisher : Springer Science & Business Media
ISBN 13 : 3540769617
Total Pages : 448 pages
Book Rating : 4.5/5 (47 download)
Download or read book Globular Clusters - Guides to Galaxies written by Tom Richtler and published by Springer Science & Business Media. This book was released on 2008-11-23 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principal question of whether and how globular clusters can contribute to a better understanding of galaxy formation and evolution is perhaps the main driving force behind the overall endeavour of studying globular cluster systems. Naturally, this splits up into many individual problems. The objective of the Joint ESO-FONDAP Workshop on Globular Clusters - Guides to Galaxies was to bring together researchers, both observational and theoretical, to present and discuss the most recent results. Topics covered in these proceedings are: internal dynamics of globular clusters and interaction with host galaxies (tidal tails, evolution of cluster masses), accretion of globular clusters, detailed descriptions of nearby cluster systems, ultracompact dwarfs, formations of massive clusters in mergers and elsewhere, the ACS Virgo survey, galaxy formation and globular clusters, dynamics and kinematics of globular cluster systems and dark matter-related problems. With its wide coverage of the topic, this book constitutes a valuable reference of the scientific knowledge of the field.
Author :
Publisher :
ISBN 13 :
Total Pages : 157 pages
Book Rating : 4.:/5 (912 download)
Download or read book Globular Cluster Systems and Their Implications of Galaxy Formation written by and published by . This book was released on 2008 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Andrés Jordán
Publisher :
ISBN 13 :
Total Pages : 224 pages
Book Rating : 4.:/5 (64 download)
Download or read book Studies of Extragalactic Globular Clusters written by Andrés Jordán and published by . This book was released on 2004 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Erin Marie O'Malley
Publisher :
ISBN 13 :
Total Pages : 390 pages
Book Rating : 4.:/5 (1 download)
Download or read book The Mystery of Globular Clusters written by Erin Marie O'Malley and published by . This book was released on 2017 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, evidence has grown for the existence of multiple stellar populations in globular clusters (GCs). However, questions remain regarding the nature of these populations. Photometric observations clearly show discrete populations while spectroscopic observations seem to show a continuous spread. This dissertation provides steps to better understanding GCs and the complexities associated with their evolution. Calibration of stellar evolution models at low metallicity is necessary for comparison to GCs. Accurate abundances of metal-poor subdwarfs are determined and used in this calibration. A Monte Carlo analysis is then performed in order to determine accurate distances, absolute ages, and integrated orbital trajectories for 24 GCs. These results are of critical importance as they not only incorporate the observational uncertainty, but also the uncertainty incurred by the models themselves. Lastly, high resolution spectra of three GCs (NGC 6681, NGC 6584 and NGC 7099) are obtained for a detailed abundance analysis of red giant branch stars. The high resolution and signal-to-noise achieved in these observations allows for the discovery of a statistically significant Na-O anticorrelation in all three clusters, the populations of which agree with those from photometric observations. Although we cannot determine precisely the nature of the polluters that were the predecessors to the enhanced populations, we do know that both s-process and r-process mechanisms contributed to the evolution and these results can be used to help constrain future models of GC polluter candidates
Author : Santi Cassisi
Publisher : John Wiley & Sons
ISBN 13 : 3527665544
Total Pages : 506 pages
Book Rating : 4.5/5 (276 download)
Download or read book Old Stellar Populations written by Santi Cassisi and published by John Wiley & Sons. This book was released on 2013-08-29 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book discusses the theoretical path to decoding the information gathered from observations of old stellar systems. It focuses on old stellar systems because these are the fossil record of galaxy formation and provide invaluable information ont he evolution of cosmic structures and the universe as a whole. The aim is to present results obtained in the past few years for theoretical developments in low mass star research and in advances in our knowledge of the evolution of old stellar systems. A particularly representative case is the recent discovery of multiple stellar populations in galactic globular clusters that represents one of the hottest topics in stellar and galactic astrophysics and is discussed in detail. Santi Cassisi has authored about 270 scientific papers, 150 of them in peer-reviewed journals, and the title Evolution of Stars and Stellar Populations.
Author : Michael John Pierce
Publisher :
ISBN 13 :
Total Pages : 99 pages
Book Rating : 4.:/5 (225 download)
Download or read book Spectroscopy of Extra-galactic Globular Clusters written by Michael John Pierce and published by . This book was released on 2006 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Regina von Berlepsch
Publisher : John Wiley & Sons
ISBN 13 : 3527644393
Total Pages : 270 pages
Book Rating : 4.5/5 (276 download)
Download or read book Zooming in written by Regina von Berlepsch and published by John Wiley & Sons. This book was released on 2013-10-14 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: High resolution is a key element in research in astronomy and cosmology. Advances in instrumentation and new methods are enabling us to constantly make new exciting discoveries, and progress in theoretical modelling allows us to gain a deeper understanding of cosmic physics. One example of this progress in instrumentation and observing strategy have made possible the discovery of a rich population of low-mass planets orbiting solar-type stars (Michel Mayor et al., Karl Schwarzschild Lecture 2010). This 23rd volume in the series Reviews of Modern Astronomy contains 14 invited reviews and highlight contributions presented during the 2010 annual meeting of the Astronomical Society on the topic "Zooming in: The cosmos at high resolution", held in Bonn, Germany, in September 2010.
Author : Bruce Jones Sams
Publisher :
ISBN 13 :
Total Pages : 442 pages
Book Rating : 4.:/5 (26 download)
Download or read book High Resolution Observations of the Globular Cluster NGC 7099 written by Bruce Jones Sams and published by . This book was released on 1991 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Alessia Moretti
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (18 download)
Download or read book Extragalactic Globular Cluster Systems written by Alessia Moretti and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : R. Giacconi
Publisher : Springer Science & Business Media
ISBN 13 : 9400984596
Total Pages : 331 pages
Book Rating : 4.4/5 (9 download)
Download or read book X-Ray Astronomy with the Einstein Satellite written by R. Giacconi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: The meeting of the High Energy Astrophysics Division of the American Astronomical Society, held in Cambridge, Massachusetts on January 28- 30, 1980, marks the coming of age of X-ray astronomy. In the 18 years since the discovery of the first extrasolar X-ray source, Sco X-l, the field has experienced an extremely rapid instrumentation development culminating with the launch on November 13, 1978 of the Einstein Observatory (HEAO-2) which first introduced the use of high resolution imaging telescopes to the study of galactic and extragalactic X-ray sources. The Einstein Observatory instruments can detect sources as faint as 10-7 Sco X-lor about 17 magnitudes fainter. The technological developments in the field have been paralleled by a host of new discoveries: in the early 1960's the detection of 9 "X-ray stars", objects 10 times more luminous in X-rays than the Sun and among the brightest stellar objects at all wavelengths; in the late 1960's and early 1970's the discovery of the nature of such systems which were identified as collapsed stars (neutron stars and black holes) in mass exchange binary systems, and the detection of the first few extragalactic sources.
Author : Edgar Smith
Publisher :
ISBN 13 :
Total Pages : 312 pages
Book Rating : 4.:/5 (466 download)
Download or read book Comparison of Globular Clusters in Formax and Satittarius with Those of the Galaxy and the Calypso High Resolution Telescope written by Edgar Smith and published by . This book was released on 2000 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : C. Martinez Roger
Publisher : Cambridge University Press
ISBN 13 : 9780521770583
Total Pages : 380 pages
Book Rating : 4.7/5 (75 download)
Download or read book Globular Clusters written by C. Martinez Roger and published by Cambridge University Press. This book was released on 1999-10-28 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: An accessible introduction to globular clusters for graduate students, and a comprehensive and up-to-date reference for researchers.
Author : R. J. Hanisch
Publisher :
ISBN 13 :
Total Pages : 632 pages
Book Rating : 4.F/5 ( download)
Download or read book Astronomical Data Analysis Software and Systems II written by R. J. Hanisch and published by . This book was released on 1993 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
