Download or read book The Role of Disks in the Angular Momentum Evolution of Young Low mass Stars written by Thompson S. Le Blanc and published by . This book was released on 2012 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Angular Momentum Evolution of Young Stars written by Santo Catalano and published by Springer Science & Business Media. This book was released on 1991 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: I. Initial Angular Momentum Distribution.- Angular Momentum Effects in Star Formation.- Evolutionary Properties of Intermediate-Mass Protostar.- Small-Scale Structure and Angular Momentum Transfer in Protostellar Environments.- Ekman Pumping in a Rotating Protostar.- Rotation in Pre-Main Sequence Stars; Properties and Evolution.- Disks Associated with Intermediate Mass Stars.- Differential Rotation of Fully Convective Pre-Main Sequence Stars.- The X-ray Emission from PMS Stars in Taurus-Auriga, and the Relationship with Other Diagnostics of Activity.- Multifrequency Monitoring of RU Lupi; Observational Results and a Model.- Polarimetry and CCD Imaging of Herbig Ae/Be Stars and Star Forming Regions.- II: Angular Momentum Evolution.- Rotational Velocities of Low Mass Stars in Young Clusters.- Rotation of Young Stars in the Orion Nebula Region.- Rotational Velocities of Stars in Open Clusters; the Time-Dependence Revisited.- Main Sequence Angular Momentum Loss in Low-Mass Stars.- The Angular Momentum Evolution of Young and Old Binary Components.- Ages of Spotted Late-Type Stars.- Rotation of Evolved Stars.- Rotational Discontinuity of Evolved Stars; What Interpretation?.- III: Consequence of Rotation.- Magnetic Activity and Rotation.- Lithium, Rotation and Age.- Rotation, Chromospheric Activity, and Lithium Abundances in G and K Dwarfs of the Pleiades.- Lithium Abundance and Rotation in Southern Chromospherically Active Stars.- Lithium Depletion Induced by Rotation in Young Stars.- Rotational Mixing and Lithium in Young Stars.- IV: Internal Rotation and Models.- Internal Solar Rotation.- Stellar Activity Belts as Potential Indicators of Internal Rotation and Angular Momentum Distribution.- Dynamics of Spot Groups and Rotation of the External Convective Layers in the Sun and Magnetically Active Stars.- Theory of Magnetic Braking of Late-Type Stars.- Pre-Main Sequence and Main Sequence Rotational Evolution; Constraints on Models Derived from Observations.- Evolutionary Models of Rotating Stars.- The Internal Rotation of the Sun; Implications on the History of its Angular Momentum.- Angular Momentum Transport, Rotational Instabilities, Magnetic Fields and Mixing.- The Spin-Down of Main Sequence Stars Based on Observed Magnetic Field Strength.- Session V: Observational Perspectives.- Observational Perspectives.- PRISMA: a Space Facility for Studying Rotation and Activity.- The Spectrum-UV Project.- Summary of the Workshop.- Panel Discussion: Initial Angular Momentum.- Panel Discussion: Dynamos and Internal Rotation.- Author Index.- Object Index.
Download or read book Formation and Evolution of Low Mass Stars written by A.K. Dupree and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book represents the Proceedings of the NATO Advanced Study Insti tute on Formation and Evolution of Low Mass Stars held from 21 September to 2 October 1987 at Viana do Castelo, Portugal. Holding the meeting in Portugal recognized both the historical aspects and the bright future of astronomy in Portugal. In the early sixteenth century, the Portugese played an important role in the critical diffusion of classical and medieval knowledge which formed so large a part of scientific activity at that time. Navigation and course setting, brought to a high level by Portugese explorers, relied on mathematics and astronomy to produce precise tables of solar positions. In contemporary Portu gal, astronomy is the focus of renewed interest and support at the universities. It is thus particularly appropriate that the NATO Advanced Study Institute was held on the coast of the Atlantic Ocean in the friendly surroundings of the Costa Verde.
Download or read book Angular Momentum Evolution of Young Stars written by S Catalano and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports the Proceedings of the NATO Advanced Research Workshop on "An gular Momentum Evolution of Young Stars" held from 17 to 21 September 1990 at Noto, Italy. The workshop had its immediate origin in a discussion about the availability of stel lar rotation data, that took place in 1987 at Viana do Castelo Portugal during the NATO meeting, Formation and Evolution of Low Mass Stars. We recognized that nearly 20 years had passed since the last meeting on stellar rotation and that significant progress in the observation of rotation rates in low mass stars had been made. During the last 20 years, new efficient instrumentation (CCD and photon counting de tectors and echelle spectrographs) and new analysis techniques (profile Fourier analysis) have allowed us to measure rotational velocities as low as 1-2 km/s and to reach low mass stars in young clusters. Even with these advances, rotational velocities of low mass stars would have remained challenging to determine if all single, low mass stars later than GO had rotational velocities of order or less than 10 km/sec. Evidence that this is not always the case was first provided by the photometric variability data obtained by van Leeuwen and Alphenaar for K dwarfs in the Pleiades and more recently by the vsini measurements of low mass stars in several young clusters.
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 Star Disk Interaction in Young Stars IAU S243 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2007 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews latest star-disk interaction region in young stars for graduate students and researchers.
Download or read book The Physics of Star Formation and Early Stellar Evolution written by Charles J. Lada and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 779 pages. Available in PDF, EPUB and Kindle. Book excerpt: The origin of stars is one of the principle mysteries of nature. During the last two decades advances in technology have enabled more progress to be made in the quest to understand stellar origins than at any other time in history. The study of star formation has developed into one of the most important branches of mod ern astrophysical research. A large body of observational data and a considerable literat ure now exist concerning this topic and a 1arge community of international astronomers and physicists devote their efforts attempting to decipher the secrets of stellar birth. Yet, the young astronomerjphysicist or more advanced researcher desiring to obtain a basic background in this area of research must sift through a very diverse and sometimes bewildering literature. A literature which includes research in many discip1ines and sub discip1ines of classical astrophysics from stel lar structure to the interstellar medium and encompasses the entire range of the electromagnetic spectrum from radio to gamma rays. Often, the reward of a suc cessfu1 foray through the current literature is the realization that the results can be obsolete and outdated as soon as the ink is dry in the journal or the conference proceeding in which they are published.
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 Open Issues in Local Star Formation written by Jacques Lépine and published by Springer Science & Business Media. This book was released on 2003-12-31 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 (i) the physics of young stellar objects, which are observed with increasing angular resolution by the new generation of telescopes, and (ii) 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. Indeed, 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, will make this book particularly useful for researchers and PhD students.
Download or read book A Search for Pulsation in Young Brown Dwarfs and Very Low Mass Stars written by Ann Marie Cody and published by Universal-Publishers. This book was released on 2013-08 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2005, Palla & Baraffe proposed that brown dwarfs and very low mass stars (
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.
Download or read book A Test of Star Formation Theory written by Keivan Guadalupe Stassen and published by . This book was released on 2000 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book From Dust To Stars written by Norbert S. Schulz and published by Springer Science & Business Media. This book was released on 2007-03-06 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of stellar formation in galaxies have a profound impact on our understanding of the present and the early universe. The book describes complex physical processes involved in the creation of stars and during their young lives. 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.
Download or read book Very Low Mass Stars and Brown Dwarfs written by Rafael Rebolo and published by Cambridge University Press. This book was released on 2000-11-27 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides a state-of-the-art review of our current knowledge of brown dwarfs and very low-mass stars. The hunt for and study of these elusive objects is currently one of the most dynamic areas of research in astronomy for two reasons. Brown dwarfs bridge the gap between stars and planets, and they may constitute an important part of the 'dark matter' of the Universe. This volume presents review articles from a team of international authorities who gathered at a conference in La Palma to assess the spectacular progress that has been made in this field in the last few years.
Download or read book The Origin of Stars and Planetary Systems written by Charles J. Lada and published by Springer Science & Business Media. This book was released on 1999-07-31 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Study Institute, The Physics of Star Formation and Early Evolution-II, held in Crete, Greece, 24 May-5 June, 1998
Download or read book Accretion Disks and the Formation of Stellar Systems written by Kaitlin Michelle Kratter and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we examine the role of accretion disks in the formation of stellar systems, focusing on young massive disks which regulate the flow of material from the parent molecular core down to the star. We study the evolution of disks with high infall rates that develop strong gravitational instabilities. We begin in chapter 1 with a review of the observations and theory which underpin models for the earliest phases of star formation and provide a brief review of basic accretion disk physics, and the numerical methods which we employ. In chapter 2 we outline the current models of binary and multiple star formation, and review their successes and shortcomings from a theoretical and observational perspective. In chapter 3 we begin with a relatively simple analytic model for disks around young, very massive stars, showing that instability in these disks may be responsible for the higher multiplicity fraction of massive stars, and perhaps the upper mass to which they grow. We extend these models in chapter 4 to explore the properties of disks and the formation of binary companions across a broad range of stellar masses. In particular, we model the role of global and local mechanisms for angular momentum transport in regulating the relative masses of disks and stars. We follow the evolution of these disks throughout the main accretion phase of the system, and predict the trajectory of disks through parameter space. We follow up on the predictions made in our analytic models with a series of high resolution, global numerical experiments in chapter 5. Here we propose and test a new parameterization for describing rapidly accreting, gravitationally unstable disks. We find that disk properties and system multiplicity can be mapped out well in this parameter space. Finally, in chapter 6, we address whether our studies of unstable disks are relevant to recently detected massive planets on wide orbits around their central stars.
Download or read book High Angular Resolution Studies of the Structure and Evolution of Protoplanetary Disks written by Joshua Eisner and published by Universal-Publishers. This book was released on 2005 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Young stars are surrounded by massive, rotating disks of dust and gas, which supply a reservoir of material that may be incorporated into planets or accreted onto the central star. In this dissertation, I use high angular resolution observations at a range of wavelengths to understand the structure, ubiquity, and evolutionary timescales of protoplanetary disks. First, I describe a study of Class I protostars, objects believed to be at an evolutionary stage between collapsing spherical clouds and fully-assembled young stars surrounded by protoplanetary disks. I use a Monte Carlo radiative transfer code to model new 0.9 micron scattered light images, 1.3 mm continuum images, and broadband spectral energy distributions. This modeling shows that Class I sources are probably surrounded by massive protoplanetary disks embedded in massive infalling envelopes. For the best-fitting models of the circumstellar dust distributions, I determine several important properties, including envelope and disk masses, mass infall rates, and system inclinations, and I use these results to constrain the evolutionary stage of these objects. Second, I discuss observations of the innermost regions of more evolved disks around T Tauri and Herbig Ae/Be stars, obtained with the Palomar Testbed and Keck Interferometers. I constrain the spatial and temperature structure of the circumstellar material at sub-AU radii, and demonstrate that lower-mass stars are surrounded by inclined disks with puffed-up inner edges 0.1-1 AU from the star. In contrast, the truncated inner disks around more massive stars may not puff-up, indicating that disk structure depends on stellar properties. I discuss the implications of these results for disk accretion, terrestrial planet formation and giant planet migration. Finally, I put these detailed studies of disk structure into a broader context by constraining the mass distribution and evolutionary timescales of circumstellar disks. Using the Owens Valley Millimeter Array, I mapped the millimeter continuum emission toward >300 low-mass stars in the NGC 2024 and Orion Nebula clusters. These observations demonstrate that the average disk mass in each cluster is comparable to the "minimum-mass protosolar nebula," and that there may be disk evolution on one million year timescales.
