Protoplanetary Disk Dynamics in High Dust-to-gas Ratio Environments PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Protoplanetary Disk Dynamics in High Dust-to-gas Ratio Environments PDF full book. Access full book title Protoplanetary Disk Dynamics in High Dust-to-gas Ratio Environments by Matías Gárate Silva. Download full books in PDF and EPUB format.
Author: Matías Gárate Silva
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Matías Gárate Silva
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Dániel Apai
Publisher: Cambridge University Press
ISBN: 0521517729
Category : Science
Languages : en
Pages : 397
Get Book Here
Book Description
The first comprehensive overview of planet formation for students and researchers in astronomy, cosmochemistry, laboratory astrophysics and planetary sciences.
Author: Jiaqing Bi
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Dust and gas in protoplanetary disks are the building blocks of planets. In this thesis, we study the dynamics of the gas and dust, which are crucial for the planet formation theory, using observational and numerical approaches. The observational part contains the case study of a rare circumtriple disk around the GW Ori hierarchical triple system. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of 1.3 mm dust continuum and 12CO J = 2-1 molecular gas emission of the disk. For the first time, we identify three dust rings in the GW Ori disk at ~46, 188, and 338 au, with the outermost ring being the largest dust ring ever found in protoplanetary disks. We use visibility modeling of the dust continuum and kinematics modeling of CO lines to show that the disk has misaligned parts, and the innermost dust ring is eccentric. We interpret these substructures as evidence of ongoing dynamical interactions between the triple stars and the circumtriple disk. In the numerical part, we study whether or not dust around gas gaps opened by planets can remain settled by performing three-dimensional, dust-plus-gas simulations of protoplanetary disks with an embedded planet. We find planets that open gas gaps 'puff up' small, sub-mm-sized grains at the gap edges, where the dust scale-height can reach 80% of the gas scale-height. We attribute this dust 'puff-up' to the planet-induced meridional gas flows previously identified by Fung and Chiang. We thus emphasize the importance of explicit 3D simulations to obtain the vertical distribution of sub-mm-sized grains around planet gaps. We caution that the gas-gap-opening planet interpretation of well-defined dust rings is only self-consistent with large grains exceeding mm in size.
Author: Diana Hernandez Juarez Madera
Publisher:
ISBN:
Category : Cosmic dust
Languages : en
Pages : 160
Get Book Here
Book Description
Author: Ana-Maria Adriana Piso
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The composition of planets is determined by and tightly linked to the composition of the protoplanetary disk in which they form. In the first part of my thesis, I study giant planet formation through core accretion. I show how the minimum core mass required to form a giant planet during the lifetime of the protoplanetary disk depends on the location in the disk, the equation of state of the nebular gas and dust opacity. This minimum applies when planetesimal accretion does not substantially heat the core's atmosphere. The minimum core mass decreases with semimajor axis, and may be significantly lower than the typically quoted value of 10 Earth masses, thus challenging previous studies that core accretion cannot operate in the outer disk. In the second part, I explore how the composition and evolution of protoplanetary disks may affect the formation and chemical composition of giant planets. Volatile snowlines are highly important in the planet formation process. I thus show how the snowline locations of the main carbon, oxygen and nitrogen carriers, as well as the C/N/O ratios, are affected by disk dynamics and ice morphology. Compared to a static disk, disk dynamics and ice morphology combined may change the CO and N_2 snowline locations by a factor of 7. Moreover, the gas-phase N/O ratio is highly enhanced throughout most of the disk, meaning that wide-separation giants should have an excess of nitrogen in their atmospheres which may be used to trace their origins. The large range of possible CO and N_2 snowline locations, and hence of regions with highly enhanced N/O ratios, implies that snowline observations at various stages of planet formation are crucial in order to use C/N/O ratios as beacons for planet formation zones.
Author: Joshua Eisner
Publisher: Universal-Publishers
ISBN: 1581122802
Category : Science
Languages : en
Pages : 240
Get Book Here
Book Description
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.
Author: Andrew W. Blain
Publisher: Springer Science & Business Media
ISBN: 3540316361
Category : Science
Languages : en
Pages : 320
Get Book Here
Book Description
This book contains the expanded lecture notes of the 32nd Saas-Fee Advanced Course. The three contributions present the central themes in modern research on the cold universe, ranging from cold objects at large distances to the physics of dust in cold clouds.
Author: Isaac Backus
Publisher:
ISBN:
Category :
Languages : en
Pages : 173
Get Book Here
Book Description
In this thesis I present my research on the early stages of planet formation. Using advanced computational modeling techniques, I study global gas and gravitational dynamics in proto- planetary disks (PPDs) on length scales from the radius of Jupiter to the size of the solar system. In that environment, I investigate the formation of gas giants and the migration, enhancement, and distribution of small solids—the precursors to planetesimals and gas giant cores. I examine numerical techniques used in planet formation and PPD modeling, especially methods for generating initial conditions (ICs) in these unstable, chaotic systems. Disk simulation outcomes may depend strongly on ICs, which may explain results in the literature. I present the largest suite of high resolution PPD simulations to-date and argue that direct fragmentations of PPDs around M-Dwarfs is a plausible path to rapidly forming gas giants. I implement dust physics to track the migration of centimeter and smaller dust grains in very high resolution PPD simulations. While current dust methods are slow, with strict resolution and/or time-stepping requirements, and have some serious numerical issues, we can still demonstrate that dust does not concentrate at the pressure maxima of spiral arms, an indication that spiral features observed in the dust component are at least as well resolved in the gas. Additionally, coherent spiral arms do not limit dust settling. We suggest a novel mechanism for disk fragmentation at large radii driven by dust accretion from the surrounding nebula. We also investigate self induced dust traps, a mechanism which may help explain the growth of solids beyond meter sizes. We argue that current apparent demonstrations of this mechanism may be due to numerical artifacts and require further investigation.
Author: Henrik Beuther
Publisher: University of Arizona Press
ISBN: 0816531242
Category : Science
Languages : en
Pages : 945
Get Book Here
Book Description
Proceedings of a conference held in Heidelberg, Germany, July 15-20, 2013.
Author: Ratko K. Janev
Publisher: Springer Science & Business Media
ISBN: 364271935X
Category : Science
Languages : en
Pages : 322
Get Book Here
Book Description
Atomic and molecular processes play an important role in laboratory and astrophysical plasmas for a wide range of conditions, and determine, in part, their electrical, transport, thermal, and radiation properties. The study of these and other plasma properties requires a knowledge of the cross sections, reaction rate coefficients, and inelastic energy transfers for a variety of collisional reactions. In this review, we provide quantitative information about the most important collision processes occurring in hy drogen, helium, and hydrogen-helium plasmas in the temperature range from 0. 1 eV to 20 keY. The material presented here is based on published atomic and molecular collision data, theoretical calculations, and appro priate extrapolation and interpolation procedures. This review gives the properties of each reaction, graphs of the cross sections and reaction rate coeffiCients, and the coefficients of analytical fits for these quantities. We present this information in a form that will enable researchers who are not experts in atomic physics to use the data easily. The authors thank their colleagues at the Princeton Plasma Physics Laboratory and in the atomic physics community who have made many useful suggestions for the selection and presentation o. f t. he material. We gratefully acknowledge the excellent technical assistance of Elizabeth Carey for the typing, and Bernie Giehl for the drafting. This work was supported in part by the U. S. Department of Energy Contract No. DE-AC02-76-CHO-3073. Princeton, USA R. K. Janev W. D. Langer September, 1987 K. Evans, Jr. , D. E.
