Download or read book Constraining Turbulence in Protoplanetary Disks written by Erik Thomas Weaver and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Our understanding of the formation of planets hinges on the study of protoplanetary disks. These disks of dust and gas form alongside young stars, and are the birthplace of planetary systems. Critical to understand- ing the myriad physical mechanisms governing the formation of planets is the turbulence in protoplanetary disks, which has thus far remained difficult to measure. Observations using the Atacama Large Millimeter Array (ALMA) offer an unprecedented view into the physical environment surrounding stars and planets as they form. This thesis presents new methods for work- ing with ALMA observations to determine important disk parameters, particularly the turbulence and temperature profiles. New software is presented which provides a powerful new tool for modeling and fitting protoplanetary disk structure, which combines state of the art ray tracing with Markov Chain Monte Carlo techniques to offer a fast and scalable modeling and fitting framework. This software is used for several projects related to disk turbulence measurement. First, it is used to demonstrate how best to determine tem- perature in protoplanetary disks from optically thick molecular emission lines observed with ALMA. Techniques are presented to avoid potential problems which lead to incorrect measurement of brightness temperature due to inclusion of optically thin emission, and improperly applied contin- uum subtraction. Application of these techniques is shown for the specific case of HD 142527, a disk which has a significant asymmetric feature, whose temperature must be determined with care. The fitting and modeling framework is also used to determine the turbulence present in a set of inclined protoplanetary disks, HD 163296, DoAr 25, and HD 142666, by determining how the vertical dust structure of these disks has settled relative to the gas structure. The models are based on observations of these disks from the ALMA Disk Substructures at High Angular Resolution Project (DSHARP) project, which provided high angular and spectral resolution observations of the continuum, as well as CO rotational transitions. In two of the cases, HD 163296 and DoAr 25, the disk turbulence appears to be quite low, and in the case of HD 142666, we place an upper bound. These fits also provide detailed models of the structure of these disks, in both gas and dust, as well as higher accuracy than before in measurements of the stellar masses.
Download or read book Probing Giant planet Forming Zones Around Solar like Stars with CO written by Mo Yu (Ph. D.) and published by . This book was released on 2017 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Protoplanetary disks are dusty disks around young stars where planets are formed. The evolution and composition of protoplanetary disks determine the time, environments and materials available for planet formation. However fundamental properties of protoplanetary disks such as mass, composition, and the angular momentum transfer mechanism are poorly constrained by observations. In this dissertation, we discuss the thermal and chemical evolution of protoplanetary disks around Solar-type stars, and evaluate methods to measure two key parameters - disk mass and turbulent velocity in the framework of an evolving disk system. We first build a chemical evolution model based on an MRI-active disk around a Solar-type star, and discuss the chemical depletion of CO due to the formation of complex organic molecules (Chapter 2). We then investigate the challenges one faces when measuring disk masses with CO due to the chemical depletion of CO and optical depth effects (Chapter 3). We propose strategies to correct for the CO depletion effect and constrain the disk mass within factor of a few accuracy. We also investigate the possibility of constraining turbulent velocities with CO line profiles in Chapter 4. Peak-to-trough ratios of CO rotational lines have been proposed as a robust probe for turbulent velocity. However we show that the peak-to-trough ratio could vary by $25\%$ due uncertainties in effects of CO depletion. One would underestimate the degree of turbulence if the chemical depletion of CO is not properly accounted for.
Download or read book From Protoplanetary Disks to Planet Formation written by Philip J. Armitage and published by . This book was released on 2019 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 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 Angular Momentum Transport by Nonlinear Hydrodynamic Turbulence in Protoplanetary Disks written by Andreas Drecker and published by . This book was released on 1998 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Accretion Disks written by F. Meyer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the advent of space observatories and modern developments in ground based astronomy and concurrent progress in the theoretical understanding of these observations it has become clear that accretion of material on to compact objects is an ubiquitous mechanism powering very diverse astrophysical sources ranging in size and luminosity by many orders of magnitude. A problem common to these systems is that the material accreted must in general get rid of its angular momentum and this leads to the formation of an Accretion Disk which allows angular momentum re-distribution and converts potential energy into radiation with an efficiency which can be higher than the nuclear burning yield. These systems range in size from quasars and active galactic nuclei to accretion disks around forming stars and the early solar system and to compact binaries such as cataclysmic variables and low-mass X-ray binaries. Other objects that should be mentioned in this context are 88433, the black hole binary candidates, and possibly gamma-ray burst sources. Observations of these systems have provided important constraints for theoretical accretion disk models on widely differing scales, lumi nosities, mass-transfer rates and physical environments.
Download or read book Chondrules and the Protoplanetary Disk written by R. H. Hewins and published by Cambridge University Press. This book was released on 1996-06-20 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 1996 text reviews current ideas about the formation of chondrules in meteorites.
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 Astrophysical Disks written by S. F. Dermott and published by . This book was released on 1992 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: A companion to earlier volumes (497, 536, 596, 617 and 631) of the Annals, this entry in the nonlinear astronomy series has contributions by most of the acknowledged experts in the field. They write on many topics, all of current interest. As several hold strong opposing views, this is a lively, important and timely publication.
Download or read book Dust Gas Instabilities in Protoplanetary Disks written by Ryosuke Tominaga and published by Springer Nature. This book was released on 2022-04-25 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: How planets form is one of the long-standing questions in astrophysics. In particular, formation scenarios of planetesimals which are kilometer-sized bodies and a precursor of planets are still unclear and under debate although some promising mechanisms have been proposed. This book highlight disk instabilities that have the potential to explain the origin of planetesimals. Using linear analyses and numerical simulations, it addresses how a disk evolves through the development of instabilities, and also presents a new instability driven by dust coagulation. As a result, the simulation demonstrates a scenario of planetesimal formation: A successive development of multiple instabilities triggers planetesimal formation in resulting dusty rings.
Download or read book High Resolution Simulations of Structure Formation in Turbulent Protoplanetary Disks written by Natascha Manger and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Protostars and Planets VI written by Henrik Beuther and published by University of Arizona Press. This book was released on 2014-12-18 with total page 945 pages. Available in PDF, EPUB and Kindle. Book excerpt: The revolutionary discovery of thousands of confirmed and candidate planets beyond the solar system brings forth the most fundamental question: How do planets and their host stars form and evolve? Protostars and Planets VI brings together more than 250 contributing authors at the forefront of their field, conveying the latest results in this research area and establishing a new foundation for advancing our understanding of stellar and planetary formation. Continuing the tradition of the Protostars and Planets series, this latest volume uniquely integrates the cross-disciplinary aspects of this broad field. Covering an extremely wide range of scales, from the formation of large clouds in our Milky Way galaxy down to small chondrules in our solar system, Protostars and Planets VI takes an encompassing view with the goal of not only highlighting what we know but, most importantly, emphasizing the frontiers of what we do not know. As a vehicle for propelling forward new discoveries on stars, planets, and their origins, this latest volume in the Space Science Series is an indispensable resource for both current scientists and new students in astronomy, astrophysics, planetary science, and the study of meteorites.
Download or read book Magnetorotational Turbulence in Protoplanetary Discs written by Markus Flaig and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Formation Evolution and Dynamics of Young Solar Systems written by Martin Pessah and published by Springer. This book was released on 2017-12-04 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book's interdisciplinary scope aims at bridging various communities: 1) cosmochemists, who study meteoritic samples from our own solar system, 2) (sub-) millimetre astronomers, who measure the distribution of dust and gas of star-forming regions and planet-forming discs, 3) disc modellers, who describe the complex photo-chemical structure of parametric discs to fit these to observation, 4) computational astrophysicists, who attempt to decipher the dynamical structure of magnetised gaseous discs, and the effects the resulting internal structure has on the aerodynamic re-distribution of embedded solids, 5) theoreticians in planet formation theory, who aim to piece it all together eventually arriving at a coherent holistic picture of the architectures of planetary systems discovered by 6) the exoplanet observers, who provide us with unprecedented samples of exoplanet worlds. Combining these diverse fields the book sheds light onto the riddles that research on planet formation is currently confronted with, and paves the way for a comprehensive understanding of the formation, evolution, and dynamics of young solar systems. The chapters ‘Chondrules – Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk’, ‘Dust Coagulation with Porosity Evolution’ and ‘The Emerging Paradigm of Pebble Accretion’ are published open access under a CC BY 4.0 license via link.springer.com.
Download or read book Protostars and Planets V written by Bo Reipurth and published by University of Arizona Press. This book was released on 2007 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'Protostars and Planets V' builds on the latest results from recent advances in ground and space-based astronomy and in numerical computing techniques to offer the most detailed and up-to-date picture of star and planet formation - including the formation and early evolution of our own solar system.
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 Treatise on Geochemistry written by and published by Newnes. This book was released on 2013-10-19 with total page 14787 pages. Available in PDF, EPUB and Kindle. Book excerpt: This extensively updated new edition of the widely acclaimed Treatise on Geochemistry has increased its coverage beyond the wide range of geochemical subject areas in the first edition, with five new volumes which include: the history of the atmosphere, geochemistry of mineral deposits, archaeology and anthropology, organic geochemistry and analytical geochemistry. In addition, the original Volume 1 on "Meteorites, Comets, and Planets" was expanded into two separate volumes dealing with meteorites and planets, respectively. These additions increased the number of volumes in the Treatise from 9 to 15 with the index/appendices volume remaining as the last volume (Volume 16). Each of the original volumes was scrutinized by the appropriate volume editors, with respect to necessary revisions as well as additions and deletions. As a result, 27% were republished without major changes, 66% were revised and 126 new chapters were added. In a many-faceted field such as Geochemistry, explaining and understanding how one sub-field relates to another is key. Instructors will find the complete overviews with extensive cross-referencing useful additions to their course packs and students will benefit from the contextual organization of the subject matter Six new volumes added and 66% updated from 1st edition. The Editors of this work have taken every measure to include the many suggestions received from readers and ensure comprehensiveness of coverage and added value in this 2nd edition The esteemed Board of Volume Editors and Editors-in-Chief worked cohesively to ensure a uniform and consistent approach to the content, which is an amazing accomplishment for a 15-volume work (16 volumes including index volume)!
