Download or read book Understanding the Enrichment of Heavy Elements by the Chemodynamical Evolution Models of Dwarf Galaxies written by Yutaka Hirai and published by Springer. This book was released on 2019-04-30 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the mechanism of enrichment of heavy elements in galaxies, a long standing problem in astronomy. It mainly focuses on explaining the origin of heavy elements by performing state-of-the-art, high-resolution hydrodynamic simulations of dwarf galaxies. In this book, the author successfully develops a model of galactic chemodynamical evolution by means of which the neutron star mergers can be used to explain the observed abundance pattern of the heavy elements synthesized by the rapid neutron capture process, such as europium, gold, and uranium in the Local Group dwarf galaxies. The book argues that heavy elements are significant indicators of the evolutionary history of the early galaxies, and presents theoretical findings that open new avenues to understanding the formation and evolution of galaxies based on the abundance of heavy elements in metal-poor stars.
Download or read book Constraints on Environmental and Secular Effects on the Chemodynamical Evolution of Dwarf Galaxies written by Ryan Leaman and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents observations and analysis relating to the understanding of processes that govern the formation and evolution of low mass galactic systems. In particular we have focused on separating out the contribution to the chemical and dynamical evolution of dwarf galaxies due to solely secular (internal) processes compared to external effects from the local environment a galaxy resides in. Our observational data focus on an extremely isolated dwarf galaxy, WLM, which we demonstrate has had a uniquely quiescent tidal history, thereby making it an excellent test case for such a study. With spectroscopic and photometric observations of the resolved stars and neutral gas in WLM we have been able to characterize the chemical, structural and kinematic properties of this gas rich dwarf galaxy. As WLM has not been subject to strong tidal or ram-pressure stripping of its stellar and gaseous populations, we have been able to compare the dynamical evolution and chemical history of WLM to theoretical models which are environment independent. A differential comparison of WLM to more environmentally processed dwarf galaxies in the Local Group has revealed that WLM's structural and dynamical state is far from the idealized picture of dIrrs as thin gas-rich rotating systems. The stellar component of WLM shows equal parts rotation and dispersion, and both the gaseous and stellar structural properties show an intrinsically thick axisymmetric configuration. The time evolution of the random (dispersion) component of the stellar orbital energy shows an increase with stellar age, which we show is consistent with secular processes alone - such as disk heating from giant molecular clouds and dark matter substructure. While the degree to which the thick structural and dynamically hot configuration for WLM is surprising, its chemical properties show remarkably consistent values with other galaxies of the same halo mass. Comparing the spatial chemical trends in WLM with other dwarf galaxies we identify a correlation between the strength of the radial abundance gradients and the angular momentum content of dwarf galaxies in the Local Group. Finally using a large sample of chemical abundance measurements in the literature for dwarf galaxies and star clusters, we demonstrate that their distributions of chemical elements all exhibit a binomial form, and use the statistical properties of the distributions to identify a new metric for differentiating low luminosity stellar systems. We further apply a simple binomial chemical evolution model to describe the self-enrichment and pre-enrichment in the two classes of objects, and suggest how this may be used to place constraints on the formation environments of globular clusters in particular.
Download or read book Early Chemical Evolution of the Galaxy written by Lamya A. Saleh and published by . This book was released on 2001 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Chemical Evolution of the Galaxy written by Francesca Matteucci and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based partly on a. lecture course given at the University of Tri este, but mostly on my own research experience in the field of galactic chemical evolution. The subject of galactic chemical evolution was started and developed by Beat rice Tinsley in the seventies and now is a flourishing subject. This book is dedi cated to the chemical evolution of our Galaxy and aims at giving an up-to-date review of what we have learned since Tinsley's pioneering efforts. At the time of writing, in fact, books of this kind were not available with the exception of the excellent book by Bernard Pagel on "Nucleosynthesis and Chemical Evolution of Galaxies" (Cambridge University Press, 1997), and the subject of galactic chem ical evolution has appeared only as short chapters in books devoted to other subjects. Therefore, I felt that a book of this kind could be useful. The book summarizes the observational facts which allow us to reconstruct the chemical history of our Galaxy, in particular the abundances in stars and in terstellar medium; in the last decade, a great deal of observational work, mostly abundance determinations in stars in the solar vicinity, has shed light on the pro duction and distribution of chemical elements. Even more recently more abun dance data have accumulated for external galaxies at both low and high redshift, thus providing precious information on the chemical evolution of different types of galaxies and on the early stages of galaxy evolution.
Download or read book Nucleosynthesis in Stellar Models Across Initial Masses and Metallicities and Implications for Chemical Evolution written by Christian Heiko Ritter and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Tracing the element enrichment in the Universe requires to understand the element production in stellar models which is not well understood, in particular at low metallicity. In this thesis a variety of nucleosynthesis processes in stellar models across initial masses and metallicities is investigated and their relevance for chemical evolution explored.Stellar nucleosynthesis is investigated in asymptotic giant branch (AGB) models and massive star models with initial masses between 1 M⊙ and 25 M⊙ for metal fractions of Z = 0.02, 0.01, 0.006, 0.001, 0.0001. A yield grid with elements from H to Bi is calculated. It serves as an input for chemical evolution simulations. AGB models are computed towards the end of the AGB phase and massive star models are calculated until core collapse followed by explosive core-collapse nucleosynthesis. The simulations include convective boundary mixing in all AGB star models and feature efficient hot-bottom burning and hot dredge-up in AGB models as well the predictions of both heavy elements and CNO species under hot-bottom burning conditions. H-ingestion events in the low-mass low-Z AGB model with initial mass of 1M⊙ at Z = 0.0001 result in the production of large amounts of heavy elements. In super-AGB models H ingestion could potentially lead to the intermediate neutron-capture process. To model the chemical enrichment and feedback of simple stellar populations in hydrodynamic simulations and semi-analytic models of galaxy formation the SYGMA module is created and its functionality is verified through a comparison with a widely adopted code. A comparison of ejecta of simple stellar populations based on yields of this work with a commonly adopted yield set shows up to a factor of 3.5 and 4.8 less C and N enrichment from AGB stars at low metallicity which is attributed to complete stellar models, the modeling of the AGB stage and hot-bottom burning in super- AGB stars. Analysis of two different core-collapse supernova fallback prescriptions show that the total amount of Fe enrichment by massive stars differs by up to two at Z = 0.02.Insights into the chemical evolution at very low metallicity as motivated by the observations of extremely metal poor stars require to understand the H-ingestion events common in stellar models of low metallicity. The occurrence of H ingestion events in super-AGB stars is investigated and identified as a possible site for the production of heavy elements through the intermediate neutron capture process. The peculiar abundance of some C-Enhanced Metal Poor stars are explained with simple models of the intermediate neutron capture process. Initial efforts to model this heavy element production in 3D hydrodynamic simulations are presented.For the first time the nucleosynthesis of interacting convective O and C shells in massive star models is investigated in detail. 1D calculations based on input from 3D hydrodynamic simulations of the O shell show that such interactions can boost the production of odd-Z elements P, Cl, K and Sc if large entrainment rates associated with O-C shell merger are assumed. Such shell merger lead in stellar evolution models to overproduction factors beyond 1 dex and p-process overproduction factors above 1 dex for 130,132Ba and heavier isotopes. Chemical evolution models are able to reproduce the Galactic abundance trends of these odd-Z elements if O-C shell merger occur in more than 50% of all massive stars.
Download or read book Nucleosynthesis and Chemical Evolution of Galaxies written by Bernard Ephraim Julius Pagel and published by Cambridge University Press. This book was released on 2009-01-15 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: A lucid introduction for advanced undergraduates and graduate students, and an authoritative overview for researchers and professional scientists.
Download or read book Dwarf Galaxies Keys to Galaxy Formation and Evolution written by Polychronis Papaderos and published by Springer Science & Business Media. This book was released on 2012-04-23 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dwarf galaxy research constitutes an extremely vibrant field of astrophysical research, with many long-standing questions still unsettled and new ones constantly arising. The intriguing diversity of the dwarf galaxy population, observed with advanced ground-based and space-borne observatories over a wide spectral window providing an unprecedented level of detail, poses new challenges for both observers and theoreticians. The aim of this symposium was to bring together these two groups to exchange ideas and new results on the many evolutionary aspects of and open issues concerning dwarf galaxies. The main topics addressed include: the birth of dwarf galaxies: theoretical concepts and observable relics across wavelengths and time, the morphological, structural and chemical evolution of dwarf galaxies, possible evolutionary connections between early-type and late-type dwarfs, the star formation history of dwarf galaxies and its dependence on intrinsic and environmental properties, the origin and implications of starburst activity in dwarf galaxies, the fate of dwarfish systems born out of tidally ejected matter in galaxy collisions.
Download or read book From Lithium to Uranium IAU S228 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2005 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of IAU S228 detailing progress in our knowledge of element production and evolution.
Download or read book Galaxies and their Masks written by David L. Block and published by Springer Science & Business Media. This book was released on 2010-11-12 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Freeman, Fellow of the Royal Society.
Download or read book Origin Of Matter And Evolution Of Galaxies written by Shigeru Kubono and published by World Scientific. This book was released on 1997-05-07 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on nucleosynthesis and chemical evolution of the universe. The discussion on the universe, using a common language of atomic elements and nucleosynthesis, is presented by leading figures from a wide variety of fields — astronomy, astrophysics, cosmology, nuclear physics and particle physics. One of the highlights is the paper on MACHO's by C Alcock, which was the first to be released to the world. Perspectives of the fields are also presented, such as the SUBARU project and the Radioactive Nuclear Beam Project at INS, University of Tokyo.
Download or read book The Galaxy Disk in Cosmological Context IAU S254 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2009-04-16 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paradigm of a dark energy- and dark matter-dominated Universe, with the hierarchical merger scenario for the formation of galaxies, has scored impressive successes in matching the observed Universe. However, the theory fails to explain the difficulty in generating ordinary disk galaxies such as the Milky Way, suggesting that some important physics must be missing in current models. IAU Symposium 254 was organized to address this question, gathering researchers from an unusually broad range of fields, from cosmology to interstellar matter, and the formation and evolution of stars. High-class reviews, lectures and posters combine to define the frontiers in the field and point the way to new avenues of research. This volume presents a unique set of succinct overviews illuminating the full range of topics in this very active field. It also honors Danish astrophysicist Bengt Strömgren (1908-1987), who laid much of the foundation for this entire field.
Download or read book Chemical Evolution of Galaxies written by Francesca Matteucci and published by Springer Science & Business Media. This book was released on 2012-01-05 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term “chemical evolution of galaxies” refers to the evolution of abundances of chemical species in galaxies, which is due to nuclear processes occurring in stars and to gas flows into and out of galaxies. This book deals with the chemical evolution of galaxies of all morphological types (ellipticals, spirals and irregulars) and stresses the importance of the star formation histories in determining the properties of stellar populations in different galaxies. The topic is approached in a didactical and logical manner via galaxy evolution models which are compared with observational results obtained in the last two decades: The reader is given an introduction to the concept of chemical abundances and learns about the main stellar populations in our Galaxy as well as about the classification of galaxy types and their main observables. In the core of the book, the construction and solution of chemical evolution models are discussed in detail, followed by descriptions and interpretations of observations of the chemical evolution of the Milky Way, spheroidal galaxies, irregular galaxies and of cosmic chemical evolution. The aim of this book is to provide an introduction to students as well as to amend our present ideas in research; the book also summarizes the efforts made by authors in the past several years in order to further future research in the field.
Download or read book The Chemical Evolution of the Galaxy written by Francesca Matteucci and published by Springer Science & Business Media. This book was released on 2001-06-30 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based partly on a. lecture course given at the University of Tri este, but mostly on my own research experience in the field of galactic chemical evolution. The subject of galactic chemical evolution was started and developed by Beat rice Tinsley in the seventies and now is a flourishing subject. This book is dedi cated to the chemical evolution of our Galaxy and aims at giving an up-to-date review of what we have learned since Tinsley's pioneering efforts. At the time of writing, in fact, books of this kind were not available with the exception of the excellent book by Bernard Pagel on "Nucleosynthesis and Chemical Evolution of Galaxies" (Cambridge University Press, 1997), and the subject of galactic chem ical evolution has appeared only as short chapters in books devoted to other subjects. Therefore, I felt that a book of this kind could be useful. The book summarizes the observational facts which allow us to reconstruct the chemical history of our Galaxy, in particular the abundances in stars and in terstellar medium; in the last decade, a great deal of observational work, mostly abundance determinations in stars in the solar vicinity, has shed light on the pro duction and distribution of chemical elements. Even more recently more abun dance data have accumulated for external galaxies at both low and high redshift, thus providing precious information on the chemical evolution of different types of galaxies and on the early stages of galaxy evolution.
Download or read book Elements and the Cosmos written by Bernard Ephraim Julius Pagel and published by Cambridge University Press. This book was released on 1992-10-15 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: While there have been many books on cosmology and galactic and stellar evolution in which abundance analysis of astrophysical objects has played some part, this book is the first one for several years where specialists in the various relevant fields discuss the basis and implications of the subject as a whole. The major aim of the book is to bring together the results from high redshift studies and galactic studies in a coherent way and to cover relevant aspects of nuclear and atomic physics.
Download or read book The Evolution of The Milky Way written by F. Matteucci and published by Springer Science & Business Media. This book was released on 2000 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: This review of the most up-to-date observational and theoretical information concerning the chemical evolution of the Milky Way compares the abundances derived from field stars and clusters, giving information on the abundances and dynamics of gas.
Download or read book Dwarf Galaxies written by Springer and published by . This book was released on 2012-04-24 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring Stellar Metallicities in Dwarf Galaxies and Their Implications written by Teresa Lynn Ross and published by . This book was released on 2015 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis I discuss issues involving stellar metallicities in dwarf galaxies. Stars reflect the gas composition at the time they formed, thereby making the metallicity distribution function (MDF - the relative number of stars as a function of metallicity) a record of the chemical evolution within a galaxy. I measure photometric metallicities using Wide Field Camera 3 (WFC3) obervations aboard the Hubble Space Telescope. Advantages of photometric metallicities include measuring every star in the field down to fainter magnitudes than allowed by spectroscopy. I quantified and calibrated the metallicity and temperature sensitivities of colors derived from nine WFC3 filters using Dartmouth isochrones and Kurucz model atmospheres. The photometric metallicities were tested and calibrated with five well studied Galactic clusters spanning three orders of magnitude in metallicity M92, NGC 6752, NGC 104, NGC 5927, and NGC 6791. The greatest accuracy in assigning metallicity was found using the (F390M-F555W) color, with the main advantage being the increased color sensitivity at low metallicity. MDFs for a population, along with chemical evolution models provide evolutionary information about gas flows and enrichment within the galaxy. I measured photometric metallicities in Leo I, Leo II, IC 1613, and Phoenix, and analytical chemical evolution models were fit to their MDFs. The MDF shapes, chemicals evolution models and dynamic histories suggest that the galactic conditions during periods of star formation influenced the metallicities. I find that the narrower MDFs are indicative of interactions occurring in concert with star formation, while a broader MDF indicates a passive evolution. Additionally, I explore ways to combine chemical evolution models and star formation histories (SFH), to quantify the metallicity evolution with time. The SFHs of Weisz et al. (2014) are assessed for their potential to determine MDFs for 40 Local Group dwarf galaxies. The SFH-MDF connection is examined by comparing similar MDFs measured by Kirby et al. (2013) and the SFHs. Galaxies with comparable MDFs show similar characteristics in their SFHs. Overall, I find that the SFH, interaction history, and stellar mass are important contributors to the metallicity enrichment in dwarf galaxies.
