Download or read book The Formation of Molecular Clouds and Stars by Turbulent Compression and Collapse written by Christoph Federrath and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Molecular Cloud and Star Formation written by Christoph Federrath and published by LAP Lambert Academic Publishing. This book was released on 2010-06 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Star Formation in Giant Molecular Clouds and the Gravitational Collapse of Binary and Magnetized Single Star Systems written by Anthony Douglas Allen and published by . This book was released on 2000 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Advances in the Collapse and Fragmentation of Turbulent Molecular Cloud Cores written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Formation and Evolution of Star Forming Filaments in Molecular Clouds written by Daisei Abe and published by Springer Nature. This book was released on with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics of the Interstellar and Intergalactic Medium written by Bruce T. Draine and published by Princeton University Press. This book was released on 2010-12-20 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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)
Download or read book Molecular Clouds And Star Formation Proceedings Of The 7th Guo Shoujing Summer School On Astrophysics written by Yuan Chi and published by World Scientific. This book was released on 1995-11-16 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Interstellar Turbulence written by José Franco and published by Cambridge University Press. This book was released on 1999-05-28 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Star Formation in Turbulent Molecular Clouds written by C. Harris and published by . This book was released on 2011 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Triggered Star Formation in a Turbulent Interstellar Medium IAU S237 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2007-05-28 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Fragmentation of Molecular Clouds and Star Formation written by E. Falgarone and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 557 pages. Available in PDF, EPUB and Kindle. Book excerpt: A few years ago, a motivation for organizing one more IAU Symposium on star for mation in Grenoble, was the anticipated completion of the IRAM interferometer on the Plateau de Bures, close to Grenoble. This choice was also a sort of late celebration of the genius of Joseph Fourier, born in Grenoble, whose work is the very fondation of in terferometry. At the time when we finally announced the advent of this conference, the first reactions we got from the community were expressions of saturation and even reject, the Symposium being unfortunately scheduled almost simultaneously as two other major meetings on closely related topics, and sponsored by different organizations. A wave of disappointment then reached the organizers. Some of us were enthusiastic enough to help the others overcome their discouragement. Let them be thanked here. There was, indeed, a deeper motivation for organizing this conference. It was to trigger the meeting and communication of physicists and astrophysicists since many of the difficulties met now in understanding the physics of the interstellar medium and its evolution toward star formation are common to several, if not most, other fields of physics. They are assigned to one origin: complexity.
Download or read book Outflow Feedback Regulated Massive Star Formation in Parsec Scale Cluster Forming Clumps written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate massive star formation in turbulent, magnetized, parsec-scale clumps of molecular clouds including protostellar outflow feedback using three dimensional numerical simulations of effective resolution 20483. The calculations are carried out using a block structured adaptive mesh refinement code that solves the ideal MHD equations including self-gravity and implements accreting sink particles. We find that, in the absence of regulation by magnetic fields and outflow feedback, massive stars form readily in a turbulent, moderately condensed clump of ≈ 1,600 M{sub {circle_dot}} (containing ≈ 102 initial Jeans masses), along with a cluster of hundreds of lower mass stars. The massive stars are fed at high rates by (1) transient dense filaments produced by large-scale turbulent compression at early times, and (2) by the clump-wide global collapse resulting from turbulence decay at late times. In both cases, the bulk of the massive star's mass is supplied from outside a 0.1 pc-sized 'core' that surrounds the star. In our simulation, the massive star is clump-fed rather than core-fed. The need for large-scale feeding makes the massive star formation prone to regulation by outflow feedback, which directly opposes the feeding processes. The outflows reduce the mass accretion rates onto the massive stars by breaking up the dense filaments that feed the massive star formation at early times, and by collectively slowing down the global collapse that fuel the massive star formation at late times. The latter is aided by a moderate magnetic field of strength in the observed range (corresponding to a dimensionless clump mass-to-flux ratio [lambda] ≈ a few); the field allows the outflow momenta to be deposited more efficiently inside the clump. We conclude that the massive star formation in our simulated turbulent, magnetized, parsec-scale clump is outflow-regulated and clump-fed (ORCF for short). An important implication is that the formation of low-mass stars in a dense clump can affect the formation of massive stars in the same clump, through their outflow feedback on the clump dynamics. In a companion paper, we discuss the properties of the lower mass cluster members formed along with the massive stars, including their mass distribution and spatial clustering.
Download or read book The Formation and Early Evolution of Stars written by Norbert S. Schulz and published by Springer Science & Business Media. This book was released on 2012-05-24 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Starburst regions in nearby and distant galaxies have a profound impact on our understanding of the early universe. This new, substantially updated and extended edition of Norbert Schulz’s unique book "From Dust to Stars" describes complex physical processes involved in the creation and early evolution of stars. It illustrates how these processes reveal themselves from radio wavelengths to high energy X-rays and gamma–rays, with special reference towards high energy signatures. Several sections devoted to key analysis techniques demonstrate how modern research in this field is pursued and new chapters are introduced on massive star formation, proto-planetary disks and observations of young exoplanets. Recent advances and contemporary research on the theory of star formation are explained, as are new observations, specifically from the three great observatories of the Spitzer Space Telescope, the Hubble Space Telescope and the Chandra X-Ray Observatory which all now operate at the same time and make high resolution space based observing in its prime. As indicated by the new title two new chapters have been included on proto-planetary disks and young exoplanets. Many more colour images illustrate attractive old and new topics that have evolved in recent years. The author gives updates in theory, fragmentation, dust, and circumstellar disks and emphasizes and strengthens the targeting of graduate students and young researchers, focusing more on computational approaches in this edition.
Download or read book The Role of Magnetic Fields in the Formation of Stars written by Derek Ward-Thompson and published by Frontiers Media SA. This book was released on 2020-06-29 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolution of Interstellar Dust Grains in Molecular Cloud Envelopes written by Leire Beitia Antero and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Star formation takes place inside cold, dense clouds of molecular material (molecularclouds) that experience a hierarchical fragmentation process. Inside these clouds the material organises itself in lamentary structures, with a density increasing at smaller scales where stars are eventually formed. The evolution ofthese clouds is aected by the injection of energy into the system. It is now widely accepted that magnetohydrodynamic turbulence contributes to sustain a molecular cloud against collapse and in consequence, directly inuences the star formation eciency. Magnetic elds, therefore, are a fundamental shaping agent of molecular clouds. The most external layers of these clouds, the so-called molecular cloud envelopes, are partially ionised due to their exposure to the ambient radiation field and hence are eectively coupled to the magnetic field. This coupling favours the propagation of hydromagnetic waves inside the clouds, increasing the turbulent state of the gas...
Download or read book The Birth of Stars and Planets written by John Bally and published by Cambridge University Press. This book was released on 2006-08-24 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher description
Download or read book Principles of Star Formation written by Peter Bodenheimer and published by Springer Science & Business Media. This book was released on 2011-07-10 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding star formation is one of the key fields in present-day astrophysics. This book treats a wide variety of the physical processes involved, as well as the main observational discoveries, with key points being discussed in detail. The current star formation in our galaxy is emphasized, because the most detailed observations are available for this case. The book presents a comparison of the various scenarios for star formation, discusses the basic physics underlying each one, and follows in detail the history of a star from its initial state in the interstellar gas to its becoming a condensed object in equilibrium. Both theoretical and observational evidence to support the validity of the general evolutionary path are presented, and methods for comparing the two are emphasized. The author is a recognized expert in calculations of the evolution of protostars, the structure and evolution of disks, and stellar evolution in general. This book will be of value to graduate students in astronomy and astrophysics as well as to active researchers in the field.
