Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 390 for “"disks"”.
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Dust in circumstellar disks
… distribution of dust particles in circumstellar disks. Using millimetre interferometric observations of optically thick disks around T Tauri stars, I provide conclusive evidence for the presence of millimetre- to centimetre-sized dust aggregates. These findings demonstrate that dust grain growth …
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Thermal shock of graphite disks
Includes bibliographical references.
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Magnetohydrodynamical phenomena in gaseous disks
… and influence of magnetic fields in gaseous disks. It builds mainly on the work of Vainstein and Ruzmaiken (1972) on the generation of galactic magnetic fields. Emphasis here is on application to accretion disks in the cataclysmic variables (CVs). These include novae, dwarf novae and …
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Magnetically torqued thin accretion disks
We consider geometrically thin accretion disks around millisecond X-ray pulsars. We start with the Shakura-Sunyaev thin disk model as a basis and modify the disk equations with a magnetic torque from the central neutron star. Disk solutions are computed for a range of neutron star magnetic fields. …
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High-resolution studies of protoplanetary disks
… mid-IR, mm) for previously unknown circumstellar disks and a study of those disk candidate objects which are not yet well characterised in the literature. 22 candidate stars, most of these constituting known exoplanet systems, were examined for circumstellar material using the Adaptive Optics …
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Accretion disks in the cataclysmic variables
… structure of gaseous circumstellar disks in vertical hydrostatic equilibrium are derived. The possibility of turbulent instablilty and the resulting viscosity laws are discussed.
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Resistive magnetohydrodynamic jets from protostellar accretion disks
Astrophysikalische Jets sind ausgedehnte, kollimierte Massenausflüsse von verschiedenen astronomischen Objekten. Zeitabhängige magnetohydrodynamische (MHD) Simulationen der Jet-Entwicklung müssen den Akrretionsprozess in der Scheibe berücksichtigen, da der Jet aus der Scheibenmaterie gespeist wird. …
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Scheduling policies for disks and disk arrays
… (i.e. a router sends the requests to one of the disks as soon as these requests arrive) versus a shared queue (i.e. the requests are held in a common queue at the router and are scheduled to be served); normal data layout versus transposed data layout (i.e. the data stored on the inner cylinders …
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Streaming Instabilities in Class 0/I Disks
… it is clear that planets form in protoplanetary disks, fragmentation and the radial drift of pebbles inhibit the growth of grains to planetesimals. To overcome these barriers, effective localized dust clumping on a short enough time scale is required. One promising solution to this problem is the …
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Magnetospheres of neutron stars accreting from disks
… strongly magnetic neutron stars accreting from disks. It may also be relevant to the luminous galactic bulge X-ray sources that display quasi-periodic oscillations in intensity. These QPO sources are thought by some to be weakly magnetic neutron stars accreting from disks. In constructing these …
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Probing planetary disks: from birth to protoplanets
Protoplanetary disks set the physical and chemical conditions for the planets that will eventually form inside of them. While the exact details of the process remain a large area of research, it is the gas and dust in these disks that will grow into planets. By the Class II phase of a protostar’s …
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Hydrodynamic and Magnetohydrodynamic Convection in Accretion Disks
… perpendicular to the plane of accretion disks have been discussed for several decades. Recent simulations combining convection and the magnetorotational instability have given fresh impetus to the debate, as the interplay of the two processes can enhance angular momentum transport, at …
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The Inner Gaseous Disks Of Herbig Be Stars
… the density structure of each inner gaseous disks was determined and estimates of the disk masses and sizes were obtained. In the modeling, the photoionizing radiation of the central B star was assumed to be disk's sole source of energy input. For the four Herbig B2e stars, BD+65 1637, HD …
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Hydrodynamical simulations of dust traps in protoplanetary disks
Las teorías actuales de formación planetaria concuerdan que los planetas se forman dentro de discos de gas y polvo alrededor de una estrella jóven. Sin embargo, no es claro cuál es el mecanismo detrás de la formación planetaria. Entre los mecanismos propuestos podemos encontrar que se podrían …
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Lattice points in disks and strongly convex domains
… number of lattice points inside a disk and that disks area, otherwise known as the lattice point discrepancy. First we state some of the required definitions and properties from Fourier analysis that will be used throughout. In particular, we establish asymptotic results for oscillatory integrals …
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Shear instabilities between accretion disks and nova objects
Classical novae are thermonuclear explosions on the surface of white dwarfs caused by accretion from a companion star. Most studies focus on modelling the explosive phase (thermonuclear runaway), while this thesis, instead, focuses on the pre-explosion stage, investigating how shear instabilities …
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Multiwavelength studies of accretion disks around compact objects
(cont.) to the XPS in SNR RCW 103. The multiple IR band measurements of 1E 1048.1-5937 provide marginal evidence for spectral flattening, and cannot rule out an accretion disk scenario for AXPs.
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Modeling Exomoon Formation in Circumplanetary Disks Using Dustpy
This study presents one-dimensional simulations of a viscously evolving, gas-starved circumplanetary disk (CPD) modeled around a Jupiter-like planet. The simulations investigate the conditions under which satellites may form, with a particular focus on identifying physical mechanisms that create …
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Magneto-centrifugal Wind with Applications to Astrophysical Accretion Disks
… potential solution at low mass loading. Gaseous disks in star-forming galaxies and active galactic nuclei may contain dynamically important magnetic fields and significant flux of cosmic rays. In contrast with radiation-pressure dominated disks, a much weaker energy input in cosmic rays is …
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