Download or read book Examining Abundance Anomalies in Globular Cluster Red Giant Stars written by Robert Michael Cavallo and published by . This book was released on 1998 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Abundance Anomalies in Globular Cluster Red Giant Stars written by Benedict Bryan Messenger and published by . This book was released on 2000 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Explaining Lithium Enriched Red Giant Branch Stars written by Claudia Aguilera-Gómez and published by Springer. This book was released on 2018-11-28 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis provides new insights into the seemingly anomalous ubiquity of lithium-rich red giant stars. The theory of stellar evolution, one of the most successful models of modern astrophysics, predicts that red giant stars should display negligible levels of lithium (Li) on their surfaces. However, Li-rich giants, defined as those showing more than three times the Li content of the Sun, are found everywhere astronomers look in apparent defiance of established theory. The author addresses this problem, analyzing the different possible explanations for such an anomaly, which include interaction with a binary companion, the production of Li in the interior of the star with its subsequent transport to stellar exteriors, and the stellar interaction with planets. The author focuses on this last possibility, where the Li enrichment may be due to the ingestion of planets or brown dwarfs as the stars in question grew in size while becoming giants. She shows that this process is indeed able to explain an important fraction of giants with Li levels above the three times solar threshold, but that some other mechanism is needed to explain the remaining fraction. While this is an important discovery in its own right, the result that makes this thesis groundbreaking is its demonstration that the threshold between Li-normal and Li-rich is mass dependent rather than a fixed proportion of the Sun’s content. This corrects a fundamental misapprehension of the phenomenon and opens up a new framework in which to understand and solve the problem. Finally, the author presents interesting observational applications and samples with which to test this new approach to the problem of Li enrichment in giants.
Download or read book Deep Mixing in Globular cluster Red Giants written by P. A. Denissenkov and published by Cambridge Scientific Publishers. This book was released on 2004 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents and reviews the results of studies on subjects closely related to the problems of abundance anomalies in globular clusters and covers in particular the problem of deep mixing in globular-cluster red giants and describes a diffusion model and a mechanism for extra mixing in red giants. The author traces the development of scenarios to explain the origin of star-to star variations in elemental abundances in globular clusters: primordial nucleosynthesis and mixing and the background to the proposal of a combined scenario and a model for the chemical evolution of globular clusters. This review provides a useful reference text for graduates and researchers in astrophysics.
Download or read book Abundance Anomalies in Globular Clusters in Light of Models of Rotating Stars written by Thibaut Decressin and published by . This book was released on 2007 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Multiple Populations in Globular Clusters of the Galactic Bulge written by Justin Arras Kader and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Globular clusters are a class of very old, massive, spherical, gravitationally bound star cluster which likely play an important, but as of yet unknown, role in the formation and evolution of galaxies. These clusters had been regarded as the archetypical example of simple stellar populations, with all stars having been born at the same time from the same star-forming gaseous material. One of the major predictions of such a model is that the stars in the cluster should have identical abundances, save for inhomogeneities caused by self-enrichment of red giant atmospheres via mixing of material processed in the inner layers of the evolved stars up to their surface. However, in several pivotal studies at the turn of the 21st century, star-to-star variations in atmospheric chemical abundance were discovered among unevolved stars on the main sequence of several Galactic globular clusters, prompting acceptance of a multiple populations model. It has since been demonstrated that almost all Galactic globular clusters harbor multiple populations. Several of the most popular models envision a first generation of stars forming in the protocluster with primordial abundances, followed by formation of a second generation out of intracluster material polluted with light element products of the CNO cycle (along with the NeNa- and MgAl-chain) processes. In these scenarios, the ejecta of SNe, which include Fe and other heavy elements, attains escape velocity and does not contribute to the abundances of the second generation. However, the complexity of the observed chemical trends has so far eluded comprehensive explanation, and there is still no unified model for the origin of multiple populations in globular clusters.In this dissertation, we seek to provide key constraints on competing models of the origin of multiple populations in globular clusters by studying the relative fraction of stars of different generations, and their distribution, among 14 inner Milky Way clusters which span a wide range in mass, dynamical age, and orbital characteristics. This work was made possible by use of the Blanco DECam Bulge Survey point source catalog, providing deep, wide-field, NUV-NIR broadband photometry for more than 250 million stars toward the southern Galactic bulge. Proper motions for many of the stars were available after cross-matching the photometric catalog with Gaia EDR3, which allowed for the creation of high resolution extinction maps toward the target clusters. The extinction maps allowed us to correct the photometry for the effects of differential reddening, which can be quite severe toward the Galactic bulge. By taking advantage of the de-reddened u-band, we showed that the Blanco photometry is capable of separating cluster red giant stars based on their N (Na) abundance, enabling wide-field studies of the populations in these clusters with large number statistics. With this preferentially metal-rich sample, we were able to test whether the well-known correlations between the properties of the populations and their parent clusters hold true at higher metallicity. We were also able to compare wide-field distributions of the cluster multiple populations with orbital and internal dynamical properties of the parent clusters, which are on preferentially disruptive orbits, in order to test dynamical models of the evolution of multiple populations.
Download or read book Literature 1991 Part 2 written by Astronomisches Rechen-Institut and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Astronomy and Astrophysics Abstracts" appearing twice a year has become oneof the fundamental publications in the fields of astronomy, astrophysics andneighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. The abstrats are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world.
Download or read book Stellar Evolution Stellar Explosions and Galactic Chemical Evolution Proceedings of the Second Oak Ridge Symposium on Atomic and Nuclear Astrophysics Oak Ridge Tennessee 2 6 December 1997 written by Mezzacappa and published by CRC Press. This book was released on 1998-01-01 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bringing together atomic physicists, nuclear physicists, astronomers, and astrophysicists from around the world, Stellar Evolution, Stellar Explosions, and Galactic Chemical Evolution focuses on stellar atmospheres; stellar evolution; stellar explosions, such as novae, supernovae, and x-ray bursters; pregalactic and galactic chemical evolution; the interstellar medium; and atomic and nuclear data for astrophysics. Consisting of invited papers, invited posters, and contributed posters, this volume covers observations, modeling, and atomic and nuclear physics foundations, including data, experiments, and theories, that are essential to understanding these important astrophysical objects and events. It documents a confluence of atomic physics, nuclear physics, and astrophysics and a confluence of data from atomic and nuclear physics experiments from current-generation astronomical instruments-all have helped advance the frontier in our understanding of the universe.
Download or read book The Effects of CNO Abundance Variations and Detailed Boundary Conditions on the Evolution of Globular Cluster Red Giants written by Cynthia Yan-oi Cheung and published by . This book was released on 1980 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cosmic Abundances written by Stephen S. Holt and published by . This book was released on 1996 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Physics of Stars written by Christian Iliadis and published by John Wiley & Sons. This book was released on 2015-04-13 with total page 675 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most elements are synthesized, or "cooked", by thermonuclear reactions in stars. The newly formed elements are released into the interstellar medium during a star's lifetime, and are subsequently incorporated into a new generation of stars, into the planets that form around the stars, and into the life forms that originate on the planets. Moreover, the energy we depend on for life originates from nuclear reactions that occur at the center of the Sun. Synthesis of the elements and nuclear energy production in stars are the topics of nuclear astrophysics, which is the subject of this book. It presents nuclear structure and reactions, thermonuclear reaction rates, experimental nuclear methods, and nucleosynthesis in detail. These topics are discussed in a coherent way, enabling the reader to grasp their interconnections intuitively. The book serves both as a textbook for advanced undergraduate and graduate students, with worked examples and end-of-chapter excercises, but also as a reference book for use by researchers working in the field of nuclear astrophysics.
Download or read book Observational Tests of Deep Mixing in Population II Red Giants written by Matthew D. Shetrone and published by . This book was released on 1996 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Could intermediate mass AGB stars produce star to star abundance variations in globular cluster red giants written by Pavel A. Denisenkov and published by . This book was released on 1996 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Abundance Effects in Classification written by B. Hauck and published by Springer Science & Business Media. This book was released on 1976-09-30 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general discussions of the roles of photometric and spectroscopic classification at Cordoba in 1971 (lAU Symposium No. 50), and of the calibration of classification indices at Geneva in 1972 (IAU Symposium No. 54), revealed clearly the steadily in creasing importance of abundance parameters. The multipliCity of these, however, raised so many new problems that it was logical that the 1975 meeting at Lausanne should be concerned with ways in which differences in abundance affect both spectral types and photometric indices. Commissions 29 and 36 joined with Commission 45 in sponsoring this Symposium. Since the date of the meeting came shortly after the formal retirement of Professor William W. Morgan from the University of Chicago, it was quickly agreed that this meeting should be dedicated to him in recognition of his unique contributions to spectral classification. In the opening paper of the Symposium Dr. Bengt Stromgren has summarized these. To his remarks we should add only that it was about 1940 that Morgan first distinguished the group of G- and K-type stars with weak CN bands and metallic lines - stars which have since been recognized as having the abundance of all metals relative to hydrogen much lower than in stars of the solar population. Spectra of two of these, HD 81192 (Boss 2527) and 8 Lep, were later shown as examples of the group in the Yerkes Atlas of 1943.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2000 with total page 856 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
