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 20 for “"Stellar winds"”.
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Polarized Bow Shock Nebulae Reveal Features of the Winds and Environments of Massive Stars
… their surroundings through their energetic stellar winds during their lifetime and through their energetic deaths as supernovae. When a stellar wind interacts with the local interstellar medium (ISM), if the relative velocity between wind and ISM is supersonic, then a stellar wind bow shock …
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Multidimensional diffusive shock acceleration in the Winds from massive stars
Nonthermal radio emission has been seen in the winds around a quarter of all O-stars. The emission is attributed to shock accelerated cosmic rays. The shocks thought to be causing the acceleration are either wind-embedded shocks due to radiative line driving instabilities in the stellar wind, or …
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Investigating Extended Gamma-Ray Sources with ASTRI and CTAO: Observation, Analysis and Modelling
… results show that the mechanical efficiency of stellar winds influences the gamma-ray morphology, and that some of the extended sources observed by LHAASO may be consistent with a YMSC origin. In summary, the thesis has: validated the ASTRI analysis pipeline with simulations; introduced refined …
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Investigating Extended Gamma-Ray Sources with ASTRI and CTAO: Observation, Analysis and Modelling
… results show that the mechanical efficiency of stellar winds influences the gamma-ray morphology, and that some of the extended sources observed by LHAASO may be consistent with a YMSC origin. In summary, the thesis has: validated the ASTRI analysis pipeline with simulations; introduced refined …
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Comprehensive analyses of massive binaries and implications on stellar evolution
Via their powerful radiation, stellar winds, and supernova explosions, massive stars (Mini & 8 M☉) bear a tremendous impact on galactic evolution. It became clear in recent decades that the majority of massive stars reside in binary systems. This thesis sets as a goal to quantify the impact of …
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Circumstellar Distribution of Dust Grains Around Proto -Planetary Nebulae: Observational Evidence for Axisymmetry and 2.5-D Radiative Transfer Model Calculations
… (PN) phase. Largely spherically symmetric circumstellar dust shells of AGB stars are known to evolve into mostly axisymmetric PNs. Since the PPN phase predates the period of final PN shaping due to interacting stellar winds, the PPN shells preserve pristine records of AGB mass loss histories. …
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Multi-dimensional simulations of bow shocks of massive, high-velocity runaway stars
Stellar bow shocks result from the supersonic collision of stellar winds ejected by runaway stars and the interstellar medium (ISM). Studying their properties provides constraints on mass-loss rates, stellar wind velocities and the properties of the ISM. In this work, we study the formation of bow …
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Testing stellar models with observations from AGB and post-AGB stars
… loss, convective mixing, and grain formation in stellar winds. From an observational point of view it is difficult to determine stellar parameters such as the initial mass and metallicity. This makes it hard to constrain theoretical models with observations. The objective of my Ph.D. thesis is to …
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Testing stellar models with observations from AGB and post-AGB stars
… loss, convective mixing, and grain formation in stellar winds. From an observational point of view it is difficult to determine stellar parameters such as the initial mass and metallicity. This makes it hard to constrain theoretical models with observations. The objective of my Ph.D. thesis is to …
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Celestial Paleontology: The Legacy of Dying Stars
… dole out their atmospheric material to the interstellar medium in dramatic stellar winds and spectacular explosions. The details of this profound metamorphosis, from star to remnant, play a key role in the next generation of star formation as well as the energetic and chemical evolution of …
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Dwarf Galaxies in a Cosmological Context: A Testbench for Galaxy Modeling
… of supernova feedback on galactic enrichment and winds. Our models include a wide range of physical effects, including metal cooling, molecular hydrogen formation and cooling, photoionization and photodissociation from a metagalactic (but not local) background, a simple prescription for …
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SALT and TESS monitoring of central stars of planetary nebulae
… (WR) CSs that commonly exhibit fast, dense stellar winds. All exhibit multipolarity in their young nebulae, Hen3-1333 has a disk and dual-dust chemistry, while the other two have central stars offset from the geometric centre of their nebulae. The objects were chosen because most of these …
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A spectral and timing study of MAXI J1820+070 during outburst
… a unique class of astrophysical systems where a stellar-mass black hole accretes matter from a companion star via accretion disks. The accretion disk emits in X-ray and UV because of the radiative losses. The transfer of matter can occur through continuous donor supply or episodic capturing of …
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Study of supernovae and massive stars and prospects with the 4m International Liquid Mirror Telescope
… energetic ionization radiation and powerful stellar winds. Furthermore, the formation of low- and intermediate-mass stars are also being regulated by them. The Carina nebula region, which hosts a large population of massive stars and several young star clusters, provides an ideal target for …
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Investigating the A-type stars using Kepler data
… the literature. Many λ Boo stars also have circumstellar material, suggesting they are potential planet hosts. This, and the use of asteroseismology to study their interiors, are two excellent reasons to adopt them as prime targets for detailed investigation with Kepler. Pulsation is a common …
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Molecular clouds and star formation in the Inner Galaxy
… to erode their natal molecular clouds via their stellar winds, ionizing radiation and supernovae. It has been proposed that the shock fronts at the edges of expanding HII regions might trigger subsequent generations of star formation (e.g. Elmegreen & Lada, 1977; Bertoldi, 1989), and there are …
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The Galactic Starburst Region NGC 3603 : exciting new insights on the formation of high mass stars
… amounts of gas and dust through their circumstellar envelopes and/or disks. Second, high mass stars form by repeated collisions (coalescence) of protostars of lower masses. Both scenarios bear difficulties which impose strong constrains on the final mass of the young star. To find evidences …
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The Magnetic Field of Protostar-Disk-Outflow Systems
Recent observations of protostellar cores reveal complex magnetic field configurations that are distorted in the innermost disk region. Unlike the prestellar phase, where the magnetic field geometry is simpler with an hourglass configuration, magnetic fields in the protostellar phase are sculpted …