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Showing 1 to 18 of 18 for “"Protostellar"”.
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Describing protostellar disk structure in Ophiuchus
… and only a few disks at the younger protostellar stage have known substructures to date. In this thesis, we present a detailed analysis of 1.3 and 0.87 mm observations of ten protostellar disks in the Ophiuchus star-forming region in a search for the origins of the substructure. Of …
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Modelling Of Protostellar Jets Using Intense Lasers
Using telescopes such as the Hubble Space Telescope, astronomers observe parsec-scale plasma jets emerging from Young Stellar Objects and colliding with the interstellar medium, generating shock structures. A set of mathematically rigorous scaling transformations exists allowing dynamic scaled …
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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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THE IMPACT OF TRIPLE STELLAR SYSTEMS ON PROTOSTELLAR DISC DYNAMICS
Theoretical challenges in modelling multiple stellar systems are mirrored by observational limitations, with multiplicity often concealed within disc cavities and hidden by surrounding material. Nevertheless, advancements in observational instruments are steadily revealing multiple stellar systems …
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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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Observations of disks around the youngest protostars: Characterizing frequency, dust properties, and magnetic fields at the earliest times
… Class I protostars have made detection of young protostellar disks difficult; before this work, only ∼15 total Class 0 and 10 Class I disks were known. While work has begun with Class 0 disks, due to their deeply enshrouded nature, there is still much left to examine regarding disk frequency, …
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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 …
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Multifluid Kelvin-Helmholtz instability in weakly ionised astrophysical plasmas
… the momentum transfer between the bowshock of a protostellar jet and its surrounding molecular cloud. In particular, changes to the development of the KH instability as a result of including the multlifluid effects of ambipolar diffusion and the Hall effect are isolated and individually studied …
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The Nonisothermal Stage of Magnetic Star Formation
… network. The thermal evolution of the protostellar core and its affect on the dynamics are followed by employing the grey flux-limited diffusion approximation. Realistic temperature-dependent grain opacities are used that account for a variety of grain compositions. We have augmented …
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Properties of turbulent star-forming clusters : models versus observations
… of the entire cluster. It is demonstrated that protostellar mass accretion is a highly dynamical and time-variant process. The peak accretion rate is reached shortly after the formation of the protostellar core. It is about one order of magnitude higher than the constant accretion rate predicted …
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Present and early star formation : a study on rotational and thermal properties
… show how the angular momentum of prestellar and protostellar cores evolves and compare our results with observed quantities. The specific angular momentum of prestellar cores in our models agree remarkably well with observations of cloud cores. Some prestellar cores go into collapse to build up …
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Circumstellar environments around the youngest protostars: interferometric observations and modeling
… nearby embedded sources in the earliest stage of protostellar evolution, i.e., Class 0 young stellar objects, using interferometric data of the Berkeley-Illinois-Maryland Association array and the Combined Array for Research in Millimeter-wave Astronomy. Protostars form through gravitational …
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Initial Conditions and Collapse of Prestellar Cores
… and the impact of interactions with other protostellar objects are analysed. In this way an ensemble of 22 individual simulations was analysed. The statistical characterisation of the resulting stellar population is consistent with the current observational data and yields a natural …
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Submillimeter heterodyne spectroscopy of star forming regions
… vibrationally excited HCN emission to probe the protostellar accretion disk in a sample of nearby high and low mass protostars of varying ages. While these observations are difficult with single dish telescopes, we show the promise of the technique, and report results on 4 sources.
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A molecular line and continuum study of water maser sources
… a class of very deeply embedded, possibly protostellar, sources which are not associated with any of the traditional indicators of star formation, such as HII regions and near-infrared emission, but which do lie close to otherwise isolated H2O masers. This thesis describes a search, based …
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Nonlinear Dynamics of Warped Astrophysical Discs
… consider a simplified model for warps in young protostellar discs, where small dust grains are coupled to the gas. By using a two-fluid approach we find the internal shearing flows associated with the warp and then perform a stability analysis in the terminal velocity approximation. This reveals …
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An unbiased infrared H2 search for embedded flows from young stars in Orion A
… ist, um die typischen Eigenschaften protostellarer Ausströmungen und deren Entwicklung festzustellen, sowie um die Rückwirkung der Ausströmungen auf die umgebende Wolke zu untersuchen. Das erste Ergebnis ist, dass Ausströmungen in Sternentstehungsgebieten tatsächlich sehr häufig sind: …