Download or read book Structure and Evolution of Circumstellar Disks a Spitzer View written by Lucas Alejo Cieza-Gonzalez and published by . This book was released on 2007 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is the sum of five studies of the structure and evolution of circumstellar disks, the birthplace of planets. These studies are all based on Infrared data from the Spitzer Space Telescope, and taken together trace the evolution of disks from the optically thick primordial stage to the optically thin debris disk stage. The five projects included in this dissertation are diverse but they are all interconnected and have a common underlying motivation: to impose observational constraints on different aspects of planet formation theories. In the first project, we study the near and mid-IR (1.2-24 [mu]m) emission of Classical T Tauri Star (CTTS), which are low-mass pre-main sequence (PMS) stars that show clear evidence for accretion. We discuss the implications of our results on the structure of their inner disks and their estimated ages. In the second project, we study the incidence as a function of age of disks around weak-line T Tauri stars (low-mass PMS stars that are mostly coeval with CTTS but that do not show clear evidence for accretion) and explore the structure of these disks. We estimate the dissipation timescale of the planet-forming region of primordial disks and discuss the implications for planet formation theories. The third and fourth projects deal with the evolution of angular momentum of PMS stars. We search for observational evidence for the connection between stellar rotation and the presence of a disk predicted by the current disk-braking paradigm, according to which the rotational evolution of PMS stars is regulated through magnetic interactions between the stellar magnetosphere and the inner disk. The last project deals with debris disks, which are second-generation disks where the dust is continuously replenished by collisions between planetesimals. We search for debris disks in the far-IR (24-160 [mu]m) around a sample of Hyades Cluster members. We discuss the implications of our results on the evolution of debris disks and on the Late Heavy Bombardment in the Solar System.
Download or read book Physical Processes in Circumstellar Disks Around Young Stars written by Paulo J. V. Garcia and published by University of Chicago Press. This book was released on 2011-05-15 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Circumstellar disks are vast expanses of dust that form around new stars in the earliest stages of their birth. Predicted by astronomers as early as the eighteenth century, they weren’t observed until the late twentieth century, when interstellar imaging technology enabled us to see nascent stars hundreds of light years away. Since then, circumstellar disks have become an area of intense study among astrophysicists, largely because they are thought to be the forerunners of planetary systems like our own—the possible birthplaces of planets. This volume brings together a team of leading experts to distill the most up-to-date knowledge of circumstellar disks into a clear introductory volume. Understanding circumstellar disks requires a broad range of scientific knowledge, including chemical processes, the properties of dust and gases, hydrodynamics and magnetohydrodynamics, radiation transfer, and stellar evolution—all of which are covered in this comprehensive work, which will be indispensable for graduate students, seasoned researchers, or even advanced undergrads setting out on the study of planetary evolution.
Download or read book The Evolution of Circumstellar Disks written by Alexander Richert and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Angular momentum conservation during protostellar collapse leads to long-lived, gas-rich circumstellar disks where planets form through the concentration of gas and dust by one or both of gravitational agglomeration and aerodynamic concentration of dust. In this dissertation, I summarize four projects aimed at understanding the evolution of planet-forming disks and the debris-dominated disks that remain after the primordial gas has been depleted. The first two projects make use of X-ray and near-infrared point source data to explore the longevity of young circumstellar disks, providing constraints on the timescales available for planet formation; the first is a study of disk depletion rates in 69 young stellar clusters, while the second examines the role of external photoevaporation by massive stars in accelerating disk depletion. Next, I discuss numerical simulations of planet--disk interactions in gas-rich, optically thick disks, with implications for the observability of newly-formed massive planets. Lastly, I present numerical simulations of gas--dust interactions in optically thin disks in order to explore their effect on disk morphology, with potential consequences for identifying embedded planets.
Download or read book Evolution of Circumstellar Disks in Binary Star Systems written by Charles Guo and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Evolution of Dust in the Terrestrial Planet Region of Circumstellar Disks Around Young Stars written by Diane Dutkevitch and published by . This book was released on 1995 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Physical Processes in Circumstellar Disks around Young Stars written by Paulo J. V. Garcia and published by University of Chicago Press. This book was released on 2011-04-15 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Circumstellar disks are vast expanses of dust that form around new stars in the earliest stages of their birth. Predicted by astronomers as early as the eighteenth century, they weren’t observed until the late twentieth century, when interstellar imaging technology enabled us to see nascent stars hundreds of light years away. Since then, circumstellar disks have become an area of intense study among astrophysicists, largely because they are thought to be the forerunners of planetary systems like our own—the possible birthplaces of planets. This volume brings together a team of leading experts to distill the most up-to-date knowledge of circumstellar disks into a clear introductory volume. Understanding circumstellar disks requires a broad range of scientific knowledge, including chemical processes, the properties of dust and gases, hydrodynamics and magnetohydrodynamics, radiation transfer, and stellar evolution—all of which are covered in this comprehensive work, which will be indispensable for graduate students, seasoned researchers, or even advanced undergrads setting out on the study of planetary evolution.
Download or read book From Disks to Planets written by Michel Blanc and published by Springer. This book was released on 2019-01-30 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume discusses the evolutionary paths linking planets and their atmospheres to their origin within circumstellar disks. It reviews the main phases of this evolution, summarizes what we understand and what are the important open questions, and suggests ways towards solutions. Dust accretion within disks generates planet cores, while gas accretion on these cores leads to the diversity of their fluid envelopes. The formation of planetary proto-atmospheres and oceans is an essential product of planet formation. A fraction of the planets retain their primary proto-atmosphere, while others lose it and may form a “secondary” atmosphere. When the disk finally dissipates, it leaves us with the combination of a planetary system and a debris disk. Using the next generation of observing facilities, we will be able to reconstruct more accurately the evolutionary paths linking stellar genesis to the possible emergence of habitable worlds. Originally published in Space Science Reviews, Volume 205, Issue 1-4, December 2016
Download or read book Properties and Evolution of Circumstellar Disks and Envelopes Around Young Low mass Stars in the Taurus Star forming Region written by Elise Furlan and published by . This book was released on 2006 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Submillimeter Constraints on the Evolution of Circumstellar Disks written by Sean M. Andrews and published by . This book was released on 2007 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Observational Constraints on Circumstellar Disk Evolution and Terrestrial Planet Formation written by Thayne Michael Currie and published by . This book was released on 2008 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Circumstellar Disk Structure and Evolution Through Resolved Submillimeter Observations written by Alanna Meredith Hughes and published by . This book was released on 2010 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Circumstellar disks provide the reservoirs of raw material and determine conditions for the formation of nascent planetary systems. This thesis presents observations from millimeter-wavelength interferometers, particularly the Submillimeter Array, that address the following outstanding problems in the study of protoplanetary disks: (1) constraining the physical mechanisms driving the viscous transport of material through the disk, and (2) carrying out detailed studies of "transitional" objects between the gas-rich protoplanetary and tenuous, dusty debris disk phases to better understand how gas and dust are cleared from the system. We study accretion processes in three complementary ways: using spatially resolved observations of molecular gas lines at high spectral resolution to determine the magnitude and spatial distribution of turbulence in the disk; using polarimetry to constrain the magnetic properties of the outer disk in order to evaluate whether the MRI is a plausible origin for this turbulence and investigating the gas and dust distribution at the outer disk edge in the context of self-similar models of accretion disk structure and evolution. The studies of transition disks use spatially resolved observations to study the detailed structure of the gas and dust in systems that are currently in the process of clearing material. We obtain snapshots of the inside-out clearing of gas and dust in several systems, and compare our observations with the theoretical predictions generated for different disk clearing mechanisms. Our observations are generally consistent with the characteristics predicted for viscous transport driven by the magnetorotational instability and disk clearing accomplished through the dual action of giant planet formation and photoevaporation by energetic radiation from the star.
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 Evolution of Gas and Dust in Protoplanetary Accretion Disks written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dust constitutes only about one percent of the mass of circumstellar disks, yet it is of crucial importance for the modeling of planet formation, disk chemistry, radiative transfer and observations. The initial growth of dust from sub-μm sized grains to planetesimals and also the radial transport of dust in disks around young stars is the topic of this thesis. Circumstellar dust is subject to radial drift, vertical settling, turbulent mixing, collisional growth, fragmentation and erosion. We approach this subject from three directions: analytical calculations, numerical simulations, and comparison to observations. We describe the physical and numerical concepts that go into a model which is able to simulate the radial and size evolution of dust in a gas disk which is viscously evolving over several million years. The resulting dust size distributions are compared to our analytical predictions and a simple recipe for obtaining steady-state dust size distributions is derived. With the numerical model at hand, we show that grain fragmentation can explain the fact that circumstellar disks are observed to be dust-rich for several million years. Finally, we investigate the challenges that observations present to the theory of grain evolution, namely that grains of millimeter sizes are observed at large distances from the star. We have found that under the assumption that radial drift is ineffective, we can reproduce some of the observed spectral indices and fluxes. Fainter objects point towards a reduced dust-to-gas ratio or lower dust opacities.
Download or read book Protoplanetary Dust written by Dániel Apai and published by Cambridge University Press. This book was released on 2010-01-21 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive overview of planet formation for students and researchers in astronomy, cosmochemistry, laboratory astrophysics and planetary sciences.
Download or read book From Protoplanetary Disks to Planet Formation written by Philip J. Armitage and published by Springer. This book was released on 2019-02-02 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Is the Sun and its planetary system special? How did the Solar system form? Are there similar systems in the Galaxy? How common are habitable planets? What processes take place in the early life of stars and in their surrounding circumstellar disks that could impact whether life emerges or not? This book is based on the lectures by Philip Armitage and Wilhelm Kley presented at 45th Saas-Fee Advanced Course „From Protoplanetary Disks to Planet Formation“ of the Swiss Society for Astrophysics and Astronomy. The first part deals with the physical processes occurring in proto-planetary disks starting with the observational context, structure and evolution of the proto-planetary disk, turbulence and accretion, particle evolution and structure formation. The second part covers planet formation and disk-planet interactions. This includes in detail dust and planetesimal formation, growth to protoplanets, terrestrial planet formation, giant planet formation, migration of planets, multi-planet systems and circumbinary planets. As Saas-Fee advanced course this book offers PhD students an in-depth treatment of the topic enabling them to enter on a research project in the field.
Download or read book Meteorites Comets and Planets written by A.M. Davis and published by Elsevier. This book was released on 2005-11-21 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 1 provides a broad overview of the chemistry of the solar system. It includes chapters on the origin of the elements and solar system abundances, the solar nebula and planet formation, meteorite classification, the major types of meteorites, important processes in early solar system history, geochemistry of the terrestrial planets, the giant planets and their satellite, comets, and the formation and early differentiation of the Earth. This volume is intended to be the first reference work one would consult to learn about the chemistry of the solar system. Reprinted individual volume from the acclaimed Treatise on Geochemistry (10 Volume Set, ISBN 0-08-043751-6, published in 2003)
