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 50 for “"molecular clouds"”.
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Fragmentation of magnetically-supported, weakly-ionized molecular clouds
… weakly- ionized, self-gravitating molecular clouds in three dimensions. Although the model clouds are supported by the magnetic field, high-density, magnetically-supercritical fragments form due to the drift between the ions and the neutrals, ambipolar diffusion. To follow the …
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Molecular clouds and star formation in the Inner Galaxy
… Stars form from the gravitational collapse of molecular gas clouds; it is the process by which cold molecular gas is transformed into the stars and planets that make up the many billions of galaxies in the observable Universe. However, there are a number of open questions that have yet to be …
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Observations of protostellar systems across sub/millimeter wavelengths in nearby molecular clouds
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms
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The Effects of Fractal Molecular Clouds on the Dynamical Evolution of Oort Cloud Comets
… of perturbing objects - enormous complexes of molecular gas called giant molecular clouds (GMCs). Recent evidence has shown that the classical picture of Oort Cloud formation is inadequate to describe certain properties of the OC. To re-investigate the dynamical evolution of the Oort Cloud, we …
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Submillimetre Studies of Pre-stellar and Starless Cores in the Ophiuchus, Taurus and Cepheus Molecular Clouds
… cores in the Ophiuchus, Taurus and Cepheus molecular clouds. We identify sources in SCUBA-2 850-μm emission, and determine temperatures by fitting a modified blackbody model to their spectral energy distributions, measured using SCUBA-2, PACS and SPIRE data. We construct convolution kernels …
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From Large-scale Molecular Clouds to Filaments and Cores : Unveiling the Role of the Magnetic Fields in Star Formation
… fields in characterizing the structure of molecular clouds. We run three-dimensional turbulent non-ideal magnetohydrodynamic simulations (with ambipolar diffusion) to see the effect of magnetic fields on the evolution of the column density probability distribution function (PDF). Our …
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The effects of ambipolar diffusion, dust, and ultraviolet radiation in the formation of cores and protostars in interstellar molecular clouds
… place within magnetically supported interstellar molecular clouds. The observed inefficiency of star formation in molecular clouds, in which only a small fraction of a cloud's mass is converted into stars, is explained naturally by magnetic support of the envelope and slow, inward drift of neutral …
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High-Resolution Imaging of Dense Gas Structure and Kinematics in Nearby Molecular Clouds with the CARMA Large Area Star Formation Survey
… thesis utilizes new observations of dense gas in molecular clouds to develop an empirical framework for how clouds form structures which evolve into young cores and stars. Previous observations show the general turbulent and hierarchical nature of clouds. However, current understanding of the star …
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Propagation of molecular outflows into inhomogeneous media
Molecular clouds have inhomogeneous density profiles and have been observed to be `clumpy' in nature, containing dense cores, rarefied filaments and cocoons. Energetic mass-ejection phenomena created during the gravitational collapse of dense cores are thought to be responsible for the molecular …
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The role of magnetic braking and ambipolar diffusion in the formation of interstellar cloud cores and protostars
The means by which parent molecular clouds give birth to stars constitutes a fundamental unsolved problem in astrophysics. Magnetic fields, which dominate thermal-pressure as a source of support against self-gravity in interstellar molecular clouds, are an important regulator of star-formation. We …
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The Next Generation Balloon-Borne Large Aperture Submillimeter Telescope (blast-Tng)
… posed by submillimeter polarimetry, the study of molecular cloud dynamics and star formation remain stunted. Previously, polarimetry data was limited to a few vectors on only the brightest areas of molecular clouds. This made drawing statistically-driven conclusions a daunting task. However, the …
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The morphology and kinematics of star forming regions
… formation, it is necessary to understand the molecular clouds from which they form. The physical properties of these clouds and the interactions between their gas and solid constituents are not well known. This thesis presents an observational study of the morphology and kinematics of carbon …
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The environmental impact of high- and low-mass stars: from formation to main sequence
… the interplay of magnetic fields and collapsing clouds, and (2) the effects of radiation from massive stars. We first compare polarization measurements of 52 Galactic star-forming regions with their locations in the Galaxy. In particular, we find that there is no correlation between the average …
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New Molecular Probes of Astronomical Sources (Interstellar Sources, Comets)
… for refining the knowledge of astronomical molecular sources. The primary project involved HCO in interstellar molecular clouds. The observational results include the verification of the identity of interstellar HCO, the confirmation of the C('+)-HCO correlation first suggested by Snyder, …
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Initial Conditions and Collapse of Prestellar Cores
… and gravity. On large scales turbulence supports molecular clouds against gravity. But on small scales turbulence is able to create dense structures by locally converging flows. Eventually these structures may be captured by their own gravity and decouple from the turbulent flow. This mechanism …
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A comparison of the HI and CO velocity dispersions of nearby galaxies
… large-scale turbulence, despite stars forming in molecular clouds and the inner regions of galaxies being dominated by molecular gas. Carbon monoxide (CO) has been used as a tracer for molecular gas. In this work HI and CO dispersions were determined for a sample of nearby galaxies and they were …
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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
Interstellar molecular clouds are generally believed to be the sites of active star formation in our galaxy. Observed densities, temperatures, and magnetic field strengths imply that well-ordered magnetic fields dominate thermal pressure in supporting these objects against self-gravity. The …
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Probing the Role Played by Magnetic Fields in Star Formation with BLASTPol
… order to map magnetic field morphology in nearby molecular clouds. The role played by magnetic fields in providing support against gravitational collapse of clouds and cores and in forming observed cloud morphology is a key outstanding question in our understanding of star formation. BLASTPol has …
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