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On The Radiation Problem Associated With Massive Star Formation
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Book Synopsis On the Radiation Problem Associated with Massive Star Formation by : Golden Gadzirayi Nyambuya
Download or read book On the Radiation Problem Associated with Massive Star Formation written by Golden Gadzirayi Nyambuya and published by LAP Lambert Academic Publishing. This book was released on 2010-12 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: That our present understanding of the birth of massive stars is lacking is without doubt. This is because of the existing acrimony between observations and theory. Sharply, theory predicts that at ten times the mass of the Sun, the radiation field of the nascent massive star should be powerful enough to cause in-fall reversal on a global scale; the corollary of which is that massive stars should not exist. Unfortunately, this is not what we see when our telescopes are pointed to the heavens. Observations thereof, indicate that stars with mass well in excess of this, do exist. Because observations take precedence over all our understanding, clearly, our theories must be at fault somehow. We revisit our understanding of the radiation problem at its most fundamental and basic level and demonstrate that indeed, we have misunderstood the matters at hand. We show that if we use the Azimuthally Symmetric Theory of Gravitation (ASTG), this problem is solved. We also show that the ASTG-model can in principle explain outflows and as-well, the fragmentation of clouds leading to the rise of the Initial Mass Function.
Book Synopsis Foundations of Radiation Hydrodynamics by : Dimitri Mihalas
Download or read book Foundations of Radiation Hydrodynamics written by Dimitri Mihalas and published by Courier Corporation. This book was released on 2013-04-10 with total page 753 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excellent, informative volume focuses on dynamics of nonradiating fluids, problems involving waves, shocks and stellar winds, physics of radiation, radiation transport, and the dynamics of radiating fluids. 1984 edition.
Book Synopsis Ionization Feedback in Massive Star Formation by : Thomas Peters
Download or read book Ionization Feedback in Massive Star Formation written by Thomas Peters and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2010-11 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the origin of high-mass stars is central to modern astrophysics. We shed light on this problem using novel radiation-hydrodynamic simulations that consistently follow the gravitational collapse of a massive molecular cloud, the subsequent build-up and fragmentation of the accretion disk surrounding the nascent star, and, for the first time, the interaction between its intense UV radiation field and the infalling material. We show that ionization feedback can neither stop protostellar mass growth nor suppress fragmentation. We present a consistent picture of the formation and evolution of H II regions that explains the observed morphology, time variability, and ages of ultracompact H II regions, solving the long-standing lifetime problem.
Book Synopsis Radiative Feedback and Massive Star Formation by : R. G. Edgar
Download or read book Radiative Feedback and Massive Star Formation written by R. G. Edgar and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Open Issues in Local Star Formation by : Jacques Lépine
Download or read book Open Issues in Local Star Formation written by Jacques Lépine and published by Springer Science & Business Media. This book was released on 2006-04-18 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: The international colloquium Open Issues in Local Star Formation and Early Stellar Evolution was focused on: the physics of young stellar objects, which are observed with increasing angular resolution by the new generation of telescopes; and the processes that triggered large scale star formation in the solar neighbourhood. The scientific presentations were not limited to these two main topics as many new and interesting results related to star formation have been obtained.; The participants presented new findings in the fields of stellar groups and associations; young stellar objects; disks; outflows and jets; the ISM conditions for star formation; and early stages of star formation. The discussions on open issues, representing problems and unanswered questions, should make this book particularly useful for researchers and PhD students.
Book Synopsis Star Formation in Galaxy Evolution: Connecting Numerical Models to Reality by : Nickolay Y. Gnedin
Download or read book Star Formation in Galaxy Evolution: Connecting Numerical Models to Reality written by Nickolay Y. Gnedin and published by Springer. This book was released on 2015-09-09 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the elaborated and updated versions of the 24 lectures given at the 43rd Saas-Fee Advanced Course. Written by four eminent scientists in the field, the book reviews the physical processes related to star formation, starting from cosmological down to galactic scales. It presents a detailed description of the interstellar medium and its link with the star formation. And it describes the main numerical computational techniques designed to solve the equations governing self-gravitating fluids used for modelling of galactic and extra-galactic systems. This book provides a unique framework which is needed to develop and improve the simulation techniques designed for understanding the formation and evolution of galaxies. Presented in an accessible manner it contains the present day state of knowledge of the field. It serves as an entry point and key reference to students and researchers in astronomy, cosmology, and physics.
Author :Space Telescope Science Institute (U.S.). Symposium Publisher :Cambridge University Press ISBN 13 :0521762634 Total Pages :253 pages Book Rating :4.5/5 (217 download)
Book Synopsis Massive Stars by : Space Telescope Science Institute (U.S.). Symposium
Download or read book Massive Stars written by Space Telescope Science Institute (U.S.). Symposium and published by Cambridge University Press. This book was released on 2009-11-12 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents observational and theoretical papers from world experts addressing the important role in astrophysics of massive stars.
Download or read book The First Stars written by Volker Bromm and published by Springer. This book was released on 2016-09-07 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation of the first stars (Pop III stars) and galaxies is one of the great outstanding challenges in modern astrophysics and cosmology. The first stars are likely key drivers for early cosmic evolution and will be at the center of attention over the next decade. The best available space and ground-based telescopes like the Hubble Space Telescope probe the Universe to high redshifts and provide us with tantalizing hints; but they cannot yet directly detect the first generation of stars and the formation of the first galaxies. This is left as key science for future telecopes like the James Webb Space Telescope. This book is based in part on classroom tested lectures related to Pop III stars, but also draws from the author's review articles of the main physical principles involved. The book will thus combine pedagogical introductory chapters with more advanced ones to survey the cutting-edge advances from the frontier of research. It covers the theory of first star formation, the relation between first stars and dark matter, their impact on cosmology, their observational signatures, the transition to normal star formation as well as the assembly of the first galaxies. It will prepare students for interpreting observational findings and their cosmological implications.
Book Synopsis Limiting Accretion Onto Massive Stars by Fragmentation-Induced Starvation by :
Download or read book Limiting Accretion Onto Massive Stars by Fragmentation-Induced Starvation written by and published by . This book was released on 2010 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly understood. Two widely discussed models are monolithic collapse of molecular cloud cores and competitive accretion. To learn more about massive star formation, we perform simulations of the collapse of rotating, massive, cloud cores including radiative heating by both non-ionizing and ionizing radiation using the FLASH adaptive mesh refinement code. These simulations show fragmentation from gravitational instability in the enormously dense accretion flows required to build up massive stars. Secondary stars form rapidly in these flows and accrete mass that would have otherwise been consumed by the massive star in the center, in a process that we term fragmentation-induced starvation. This explains why massive stars are usually found as members of high-order stellar systems that themselves belong to large clusters containing stars of all masses. The radiative heating does not prevent fragmentation, but does lead to a higher Jeans mass, resulting in fewer and more massive stars than would form without the heating. This mechanism reproduces the observed relation between the total stellar mass in the cluster and the mass of the largest star. It predicts strong clumping and filamentary structure in the center of collapsing cores, as has recently been observed. We speculate that a similar mechanism will act during primordial star formation.
Book Synopsis Star Formation by : Mark R. Krumholz
Download or read book Star Formation written by Mark R. Krumholz and published by World Scientific Publishing Company. This book was released on 2017 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observing the cold interstellar medium -- Observing young stars -- Chemistry and thermodynamics -- Gas flows and turbulence -- Magnetic fields and magnetized turbulence -- Gravitational instability and collapse -- Stellar feedback -- Giant molecular clouds escales -- The star formation rate at galactic scales: observations -- The star formation rate at galactic scales: theory -- Stellar clustering -- The initial mass function: observations -- The initial mass function: theory -- Protostellar disks and outflows: observations -- Protostellar disks and outflows: theory -- Protostar formation -- Protostellar evolution -- Massive star formation -- The first stars -- Late-stage stars and disks -- The transition to planet formation
Book Synopsis The Formation of Stars by : Steven W. Stahler
Download or read book The Formation of Stars written by Steven W. Stahler and published by John Wiley & Sons. This book was released on 2008-07-11 with total page 865 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text for physics and astronomy graduate students, and as a reference for professional scientists.
Book Synopsis The Physics and Chemistry of the Interstellar Medium by : A. G. G. M. Tielens
Download or read book The Physics and Chemistry of the Interstellar Medium written by A. G. G. M. Tielens and published by Cambridge University Press. This book was released on 2005-08-25 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Book Synopsis Astrophysical Masers and Their Environments (IAU S242) by : International Astronomical Union. Symposium
Download or read book Astrophysical Masers and Their Environments (IAU S242) written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2008-02-14 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical masers, naturally occurring microwave and radio-wave emissions, provide an important tool to investigate astrophysical environments. Several thousand maser sources have been observed in the interstellar medium and star formation regions, in the expanding winds from evolved stars, in the compressed shells of supernovae remnants, in comets and in the centers of galaxies. Masers are also useful for studying the structure and dynamics of our own galaxy, while masers in other galaxies are now used for cosmological studies and studies of galactic nuclei. This volume contains the latest research on the topic as presented at IAU Symposium 242, only the third international symposium on astrophysical masers. Over 125 astronomers from 18 different countries gathered in Alice Spring, Australia, for discussions on maser research.
Book Synopsis Massive Stars, Their Lives in the Interstellar Medium by : Joseph P. Cassinelli
Download or read book Massive Stars, Their Lives in the Interstellar Medium written by Joseph P. Cassinelli and published by . This book was released on 1993 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Destructive Birth of Massive Stars & Massive Star Clusters by : Anna L. Rosen
Download or read book The Destructive Birth of Massive Stars & Massive Star Clusters written by Anna L. Rosen and published by . This book was released on 2017 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: The injection of energy and momentum into the interstellar medium by young massive stars' intense radiation fields and their fast, radiatively driven winds can have a profound influence on their formation and environment. Massive star forming regions are rare and highly obscured, making the early moments of their formation difficult to observe. Instead, we must turn to theory to elucidate the physics involved in the formation of massive stars and massive star clusters (MSCs), which can host thousands of massive stars. In my thesis, I developed analytical and numerical techniques to study the formation of massive stars and how stellar wind feedback affects the dynamics of gas that surrounds MSCs. To estimate the initial rotation rates of massive stars at birth, I developed a protostellar angular momentum evolution model for accreting protostars to determine if magnetic torques can spin down massive stars during their formation. I found that magnetic torques are insufficient to spin down massive stars due to their short formation times and high accretion rates. Radiation pressure is likely the dominate feedback mechanism regulating massive star formation. Therefore detailed simulation of the formation of massive stars requires an accurate treatment of radiation. For this purpose, I developed a new, highly accurate radiation algorithm that properly treats the absorption of the direct radiation field from stars and the re-emission and processing by interstellar dust. With this new tool, I performed a suite of three-dimensional adaptive mesh refinement radiation-hydrodynamic simulations of the formation of massive stars from collapsing massive pre-stellar cores. I found that mass is channeled to the massive star via dense infalling filaments that are uninhibited by radiation pressure and gravitational and Rayleigh-Taylor instabilities. To determine the importance of stellar wind feedback in young MSCs, I used observations to constrain a range of kinetic energy loss channels for the hot gas produced by the shock-heating of stellar winds to explain the low X-ray luminosities observed in Hii regions. I demonstrated that the energy injected by stellar winds is not a significant contributor to stellar feedback in young MSCs.
Book Synopsis Principles of Star Formation by : Peter Bodenheimer
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.
Book Synopsis Cores to Clusters by : M.S. Nanda Kumar
Download or read book Cores to Clusters written by M.S. Nanda Kumar and published by Springer Science & Business Media. This book was released on 2008-04-07 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: It was with pleasure that CAUP became for three days the core to the cloud of star formation experts all over the world. Close to the celebration of its 15th anniversary – therefore still in the early stages of institutional evolution – we are proud of our multiple activities in Astronomy: a productive research centre, classi?ed as “Institution of excellence” within the Portuguese research units, but also an “Institution of Public Utility” as recognised by the Government. Fifteen years ago we choose to play a role not only in research, as expected from any research centre but also in the training of the future astronomers and the promotion of science and scienti?c culture. This choice is clearly stated in our by-laws and also in the multiple activities we have carried out since. Along the years we have organized on a regular basis international Workshops similar to “Cores to Clusters”. Sometimes we have chosen to organize int- national conferences of a larger size. On other occasions the choice has been for smaller and more informal discussion meetings. Or even doctoral schools with very different objectives. In common all those meetings have always had, besides the formal registered participants, a group of informal participants, our undergraduate students of Astronomy, so eager to be in touch with the real world.
