Download or read book Studies of the Globular Cluster NGC 6397 Using Multi wavelength Hubble Space Telescope Images written by Liliana Ivonne Lopez Mendez and published by . This book was released on 2008 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Progress in Globular Cluster Research written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Globular clusters are extreme stellar populations. They have the highest stellar density, and host both the oldest and most metal-poor stellar populations in the Galaxy. Their densities make them excellent testbeds for stellar dynamics, while the properties of their stars allows us to test our understanding of old and metal-poor stellar evolution. This thesis is comprised of three projects studying the two nearest globular clusters, NGC 6397 and Messier 4. By examining high-quality HST photometry of NGC 6397, we have constrained the binary fraction in both the central regions, and beyond the half-light radius. We find a binary fraction of ~0.05 in the core and ~0.015 in the outskirts. In the context of recent N-body simulations by Hurley et al., we interpret the observed binary fraction in the outer field as the primordial binary fraction. This value is lower than typically assumed, and has implications for cluster dynamics and N-body modeling. We report the discovery that young white dwarfs are dynamically hotter than their progenitors. Using the same photometry as mentioned above, and archival HST photometry of Messier 4, we have found that young white dwarfs have an extended radial distribution, and therefore a higher velocity dispersion, compared with older white dwarfs and their progenitors. This implies the existence of a ``natal kick''. Implications for cluster dynamics and stellar evolution are discussed. Finally, we present the spectra of 23 white dwarfs in Messier 4 obtained with the Keck/LRIS and Gemini/GMOS spectrographs. We find that all white dwarfs are of type DA. Assuming the same DA/DB ratio as is observed in the field, the chance of finding no DBs in our sample due to statistical fluctuations is 0.006. This suggests DB formation is suppressed in the cluster environment. Furthermore, we constrain the mass of these white dwarfs by fitting models to the spectral lines. Our best estimate of the masses of the white dwarfs currently forming in Messier 4.
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 Globular Cluster NGC 6397 written by Irving R. Greenbaum and published by . This book was released on 1950 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hubble Focus the Lives of Stars written by NASA and published by . This book was released on 2021-07-19 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: INTRODUCTION This is part of a series called Hubble Focus. Each book presents some of Hubble's more recent and important ob- servations within a particular topic. The subjects span from our nearby solar system out to the horizon of Hubble's ob- servable universe. This book, Hubble Focus: The Lives of Stars, highlights some of Hubble's recent discoveries about the birth, evolution, and death of stars. Hubble's contributions are often in partnership with other space telescopes as well as those on the ground, and they build on decades of discoveries that came before Hubble's launch. Its findings are helping us under- stand how our universe has come to be the way it is today.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1998 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Membership of the Globular Cluster NGC 6397 written by E. A. Mallia and published by . This book was released on 1975 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Science with the Hubble Space Telescope written by Piero Benvenuti and published by . This book was released on 1992 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Newsletter written by and published by . This book was released on 1992 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measuring the Growth of Structure with Multi wavelength Surveys of Galaxy Clusters written by and published by . This book was released on 2008 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current and near-future galaxy cluster surveys at a variety of wavelengths are expected to provide a promising way to obtain precision measurements of the growth of structure over cosmic time. This in turn would serve as an important precision probe of cosmology. However, to realize the full potential of these surveys, systematic uncertainties arising from, for example, cluster mass estimates and sample selection must be well understood. This work follows several different approaches towards alleviating these uncertainties. Cluster sample selection is investigated in the context of arcminute-resolution millimeter-wavelength surveys such as the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT). Large-area, realistic simulations of the microwave sky are constructed and cluster detection is simulated using a multi-frequency Wiener filter to separate the galaxy clusters, via their Sunyaev-Zel'dovich signal, from other contaminating microwave signals. Using this technique, an ACT-like survey can expect to obtain a cluster sample that is 90% complete and 85% pure above a mass of 3 x 10^14 Msun. Cluster mass uncertainties are explored by comparing X-ray and weak-lensing mass estimates for shear-selected galaxy clusters in the Deep Lens Survey (DLS) to study possible biases in using cluster baryons or weak-lensing shear as tracers of the cluster total mass. Results are presented for four galaxy clusters that comprise the top-ranked shear-selected system in the DLS, and for three of these clusters there is agreement between X-ray and weak-lensing mass estimates. For the fourth cluster, the X-ray mass estimate is higher than that from weak-lensing by 2-sigma, and X-ray images suggest this cluster may be undergoing a merger with a smaller cluster, which may be biasing the X-ray mass estimate high. The feasibility of measuring galaxy cluster peculiar velocities using an ACT-like instrument is also investigated. Such a possibility would allow one to measure structure growth via large-scale velocity fields and circumvent the uncertainties associated with measuring cluster masses. We show that such measurements are possible and yield statistical uncertainties of roughly 100 km/sec given either a temperature prior with 1-sigma errors of less than 2 keV or additional lower frequency millimeter-band observations.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamical Evolution of Globular Clusters written by Lyman Spitzer, Jr. and published by Princeton University Press. This book was released on 2014-07-14 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the world's most distinguished astrophysicists presents a comprehensive theoretical treatment of the dynamical evolution of globular clusters. Lyman Spitzer's research in this field established the framework for decades of investigation. Now he summarizes in a unified, systematic way this branch of theoretical astrophysics with its still challenging problems. Originally published in 1988. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stellar Populations written by Alvio Renzini and published by John Wiley & Sons. This book was released on 2012-09-19 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: This up-to-date reference on stellar populations and development models includes coverage of distant galaxies, chemical evolution and supernovae. Written by highly acclaimed authorities in the field, the book makes use of specific problems to reveal the "kitchen secrets."
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.
