Global ETD Search
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Showing 1 to 17 of 17 for “"self-gravity"”.
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Dynamical instabilities in disc-planet interactions
… migration. I then examine the role of disc self-gravity on the vortex instabilities. It can be shown that self-gravity has a stabilising effect. Linear numerical calculations confirms this. When applied to disc-planet systems, modes with small azimuthal wavelengths are preferred with …
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The role of magnetic braking and ambipolar diffusion in the formation of interstellar cloud cores and protostars
… thermal-pressure as a source of support against self-gravity in interstellar molecular clouds, are an important regulator of star-formation. We study the formation and contraction of fragments (or cores) in isothermal, rotating, magnetic molecular clouds. Initial states are exact equilibria with …
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Star formation in the presence of magnetic fields: Molecular cloud core formation and dynamical contraction due to ambipolar diffusion; a simulation with axial symmetry
… pressure in supporting these objects against self-gravity. The magnetic force is transferred to the neutrals through collisions with ions. Because the degree of ionization drops as the density increases, redistribution of the mass-to-flux ratio in a cloud's central flux tubes (ambipolar …
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Phase Space Structure of Disequilibrium in the Milky Way
… their formation and evolution in the presence of self gravity. In doing so, we have demonstrated the first application of DMD to collisionless, self-gravitating systems. We show by comparison of self-gravitating and independent-particle simulations in a realistic Milky Way model, that the …
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The Role of MHD Waves and Ambipolar Diffusion in the Formation of Interstellar Cloud Cores and Protostars
… fields are the dominant means of support against self-gravity and, therefore, important in regulating the rate at which stars form. We formulate the problem of the self-initiated formation and contraction of cloud cores due to ambipolar diffusion in isothermal, magnetic molecular clouds in the …
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The role of ambipolar diffusion in the formation of interstellar cloud cores and protostars
… forces in supporting these objects against self-gravity. The anisotropy of the Lorentz force, which is always perpendicular to the magnetic field, allows a simplified treatment of the dynamics involving motion along the magnetic field. We derive a reduced system of non-linear, non-ideal …
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The role of ambipolar diffusion in the formation of interstellar cloud cores and protostars
… forces in supporting these objects against self-gravity. The anisotropy of the Lorentz force, which is always perpendicular to the magnetic field, allows a simplified treatment of the dynamics involving motion along the magnetic field. We derive a reduced system of non-linear, non-ideal …
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Dynamics of dense gas-star systems : Black holes and their precursors
… in the evolution of a spherical cluster, like self-gravity, two-body relaxation etc, the interaction with a central black hole and the role of a mass spectrum. Not only embark we upon this subject, but we set about an analysis on super-massive stars. How these stars could power the quasar …
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Observable signatures of general relativistic dynamics in compact binaries
… calculations of this effect have used Newtonian self-gravity, which is inappropriate for a neutron star; we correct this by using relativistic perturbation theory.
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Stellar Spiral Structures in Realistic Dark Matter Haloes
… transient multi-armed spiral structures if the self-gravity in disc is strong enough. Evolution of spiral structures is similar when the disc and the halo are misaligned, although warps develop additionally. I further find a strong correlation between the torque strength from the halo and the …
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Zonal flows in accretion discs and their role in gravito-turbulence
… focuses on the evolution of zonal flows in self-gravitating accretion discs and their resulting effect on disc stability; it also studies the process of disc gravito-turbulence, with particular emphasis given to the way the turbulent state is able to extract energy from the background flow …
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The effects of stochastic forces on the evolution of planetary systems and Saturn's rings
… that allows for the correct treatment of self-gravity for a marginally collisional system by taking into account the relevant small scale processes. Interestingly, this system is dynamically very similar to Saturn’s rings.
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The Chemical and Dynamical Evolution of Simulated Late-Type Galaxies
… (photometric, effective temperature and surface gravity). Incorporating these factors within the simulation data, we find that simply taking a spatial cut alone within a simulation model is not sufficient to match simulated abundances like for like with observational surveys. For complete …
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Mapping the interstellar magnetic field: Observations of the Goldreich-Kylafis effect towards late-type evolved stars and star-forming regions
… that support the cloud from collapsing against self gravity (Krumholz and Tan, 2007). We studied the massive star-forming region G10.6-0.4 in ALMA Band 3 polarization observation. G10.6-0.4 is one of the most luminous HII regions with embedded OB stars and thus is a good template for …
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Planet formation and evolution in protoplanetary disc
… that can later collapse under the action of self-gravity. In this thesis, we investigate the emission of systems undergoing streaming instability that we simulate through 2D local simulations using the hybrid code ATHENA. By comparing the simulated systems before and after particle clumping …
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Present and early star formation : a study on rotational and thermal properties
We investigate the rotational and thermal properties of star-forming molecular clouds using hydrodynamic simulations. Stars form from molecular cloud cores by gravoturbulent fragmentation. Understanding the angular momentum and the thermal evolution of cloud cores thus plays a fundamental role in …
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Magnetized models for the formation of the moon
… subject to a planetary equation of state with self-gravity. Herein, we have implemented various extensions to the Athena++ framework (Stone et al., 2020) that enable (1) fully conservative self-gravitating (magneto)hydrodynamics (Mullen et al., 2021), (2) super-time-stepping algorithms for …