The Formation of Molecular Clouds and Stars by Turbulent Compression and Collapse PDF Download

Author: Christoph Federrath
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Christoph Federrath
Publisher: LAP Lambert Academic Publishing
ISBN: 9783838364933
Category :
Languages : en
Pages : 212

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Book Description
Turbulent compression is considered a key process in molecular cloud and star formation. Over the last years, interstellar turbulence has thus been studied both in direct observations and in computer simulations. Apart from Kolmogorov s phenomenological model of incompressible turbulence, however, a complete theory of highly compressible turbulence remains elusive. The goal of this work is to improve our understanding of the role of interstellar turbulence for star formation. In particular, the two limiting cases of turbulence energy injection are investigated in hydrodynamical computer simulations: solenoidal forcing and compressive forcing. It is shown that these two limiting cases yield significantly different turbulence statistics and star formation rates. Different observed regions also show evidence of different mixtures of compressive and solenoidal forcing. This work should be useful for both observational and theoretical astrophysicists, as well as for readers interested in more general properties of interstellar turbulence and star formation, and in how these are modeled in computer simulations.

Author: Anthony Douglas Allen
Publisher:
ISBN:
Category :
Languages : en
Pages : 378

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The formation of Giant Molecular Clouds (GMCs) sets the stage for the formation of protostellar systems by the gravitational collapse of dense regions within the GMC that fragment into smaller core components that in turn condense into stars. Developing a comprehensive theory of star formation remains one of the most elusive, and most important, goals of theoretical astrophysics. Inherent in the difficulty in attaining this goal is that the gravitational collapse depends critically upon initial conditions within the cores which only recently have been known with sufficient accuracy to permit a realistic theoretical attack on the problem. Observations of stars in the vicinity of the Sun show that binary systems are prevalent and appear to be a general outcome of the collapse and fragmentation process. Despite years of progress, theoretical studies have still not determined why binary stars occur with such frequency, or indeed, even what processes determine the transition from single stars to binaries and thence to multiple stellar systems. One of the major goals of this research is to understand the nature of the formation of binary and multiple stellar systems with typical low mass stars 0.2 to 3 M{sub {circle_dot}} and the physical properties of these systems. Basic questions concerning this process remain unanswered. What determines the fraction of an unstable cloud that will fragment into protostellar objects? What determines the pattern of stellar clustering into binaries and multiple systems? Even after fragmentation occurs, we have little understanding of the subsequent collapse. Consequently, it is unclear how the mass distribution of fragments maps onto eventual stellar masses, something we must understand to explain the stellar initial mass function (IMF). We will first discuss the development of the numerical methodology that will contribute to answering these questions. This technology consists of a 3D parallel, adaptive mesh refinement (AMR) self-gravitational, radiation-hydrodynamics code that we have developed. We will present new results for the gravitational collapse and fragmentation of marginally stable turbulent molecular cloud cores and follow the collapse of high mass fragments as they interact with the radiation of the protostars forming at their centers. We will discuss the theoretical difficulties in forming binary stars and the role of turbulence in their formation.

Author: Daisei Abe
Publisher: Springer Nature
ISBN: 9819764149
Category :
Languages : en
Pages : 109

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Author: Bruce T. Draine
Publisher: Princeton University Press
ISBN: 1400839084
Category : Science
Languages : en
Pages : 560

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This is a comprehensive and richly illustrated textbook on the astrophysics of the interstellar and intergalactic medium--the gas and dust, as well as the electromagnetic radiation, cosmic rays, and magnetic and gravitational fields, present between the stars in a galaxy and also between galaxies themselves. Topics include radiative processes across the electromagnetic spectrum; radiative transfer; ionization; heating and cooling; astrochemistry; interstellar dust; fluid dynamics, including ionization fronts and shock waves; cosmic rays; distribution and evolution of the interstellar medium; and star formation. While it is assumed that the reader has a background in undergraduate-level physics, including some prior exposure to atomic and molecular physics, statistical mechanics, and electromagnetism, the first six chapters of the book include a review of the basic physics that is used in later chapters. This graduate-level textbook includes references for further reading, and serves as an invaluable resource for working astrophysicists. Essential textbook on the physics of the interstellar and intergalactic medium Based on a course taught by the author for more than twenty years at Princeton University Covers radiative processes, fluid dynamics, cosmic rays, astrochemistry, interstellar dust, and more Discusses the physical state and distribution of the ionized, atomic, and molecular phases of the interstellar medium Reviews diagnostics using emission and absorption lines Features color illustrations and detailed reference materials in appendices Instructor's manual with problems and solutions (available only to teachers)

Author: Yuan Chi
Publisher: World Scientific
ISBN: 9814550493
Category :
Languages : en
Pages : 330

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This volume is composed of four major in-depth yet pedagogic review chapters on the subject of star formation, written by the foremost researchers in the field. Recent infrared and millimeter radio observations are respectively reviewed by Charlie Lada and Phil Myers, both of Harvard-Smithsonian Center for Astrophysics. The theoretical work is reviewed by Frank Shu of UC-Berkeley on the gravitational collapse of dense cores in a giant molecular cloud to form sunlike stars and Bruce Elmegreen of IBM-Watson on the gravitational instability, leading to large-scale star formation. They have written at a level most suitable for graduate students or young researchers who want to develop their research interest in the field, with the most complete literature survey to date. This volume is not an ordinary conference proceedings, but a textbook to be used in graduate study in astrophysics. The volume also includes other short and interesting contributions from Doug Lin of UC-Santa Cruz, Paul Ho of Harvard-Smithsonian, Masa Hayashi of Tokyo University, Debra Elmegreen of Vassar, Jing-Yao Hu of Beijing Observatory, Guo-Xuan Sung of Shanghai Observatory, Chi Yuan of CCNY and ASIAA, and Wen-Ping Chen of Central University, Taiwan.

Author: José Franco
Publisher: Cambridge University Press
ISBN: 9780521651318
Category : Science
Languages : en
Pages : 304

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This timely volume presents a series of review articles covering every aspect of interstellar turbulence--from accretion disks, molecular clouds, atomic and ionized media, through to spiral galaxies - based on a major international conference held in Mexico City.With advances in observational techniques and the development of more efficient computer codes and faster computers, research in this area has made spectacular progress in recent years. This book provides a comprehensive overview of the most important developments in observing and modelling turbulent flows in the cosmos. It provides graduate student and researchers with a state-of-the-art summary of observational, theoretical and computational research in interstellar turbulence.

Author: C. Harris
Publisher:
ISBN:
Category : Interstellar molecules
Languages : en
Pages : 15

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Author: International Astronomical Union. Symposium
Publisher: Cambridge University Press
ISBN: 9780521863469
Category : Science
Languages : en
Pages : 544

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New stars form in the dense turbulent gas clouds of galaxies, and the formation of these clouds is the subject of the IAU S237. This book is the most up-to-date review of all aspects of cloud and star formation, and one of the few compendiums available on ISM turbulence.