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 21 for “"Young stellar objects"”.
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Characterization of Radio Emission from Young Stellar Objects
… results of detecting radio emissions from young stellar objects (YSOs), primarily using the Very Large Array (VLA). The findings are discussed in the context of likely physical mechanisms that produce the observed signals, which would inform us of the energetic phenomena that occur at a …
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Radio Observations of Discs around Young Stellar Objects
In this thesis we study the disc surrounding the Young Stellar Object DG Tau B. We present observations at both cm and mm wavelengths using e-MERLIN and the EVLA respectively. We study the cold dust in the disc of DG Tau B by looking at its spectral energy distribution (SED). We also analyse the …
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The characterization of volatiles associated with young stellar objects
… H₂O at 15 µm and 6 µm, respectively, toward 28 Young Stellar Objects (YSOs). We found that more than 50% of the YSOs studied contained a portion of crystalline CO₂ ice. We also found that some sources with Flat or borderline Class II Spectral Energy Distributions (SEDs) have a larger abundance …
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The Evolution of Massive Young Stellar Objects in the Large Magellanic Cloud
… catalog to date of infrared spectra of massive young stellar objects in the Large Magellanic Cloud. Evidenced by their very different spectral features, the luminous objects span a range of evolutionary states from those most embedded in their natal molecular material to those that have …
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Circumstellar Structure Properties of Young Stellar Objects: Envelopes, Bipolar Outflows, and Disks
… properties of the three main structures in young stellar objects (YSOs), envelopes, bipolar outflows, and circumstellar disks, have been studied using radio interferometers: the Berkeley-Illinois-Maryland Association (BIMA) array and the Combined Array for Research in Millimeter-wave …
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High resolution studies of early type emission line stars
… presents a study of early type, emission line objects on small angular scales. Spectroastrometry is used to separate the spectra of unresolved Herbig Ae/Be binary systems. The separated spectra allow the mass ratio of the systems to be established. The separation and mass ratio distribution of …
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High Spatial Resolution Observations of Young Stellar Binaries
… with magnitude cutoff (m_K <= 10.5 mag) of 158 young stellar objects located in the Ophiuchus molecular clouds is presented. All companions in the separation range 0.13 arcsec to 6.4 arcsec with flux ratios >= 0.1 at the diffraction limit could be detected by using speckle techniques. The degree …
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Circumstellar environments around the youngest protostars: interferometric observations and modeling
… 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 collapse …
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The environmental impact of high- and low-mass stars: from formation to main sequence
… are involved which complicates studies of stellar interaction. This thesis focuses on two different physical phenomena associated with stars: (1) the interplay of magnetic fields and collapsing clouds, and (2) the effects of radiation from massive stars. We first compare polarization …
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Modelling Of Protostellar Jets Using Intense Lasers
… 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 models of radiative, yet otherwise ideal, hydrodynamic flows to be …
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Optical spectroscopic studies of two star forming regions
… The goals of this study were to identify young stellar objects (YSOs) and estimate ages and masses in order to infer an initial mass function (IMF), investigate disk evolution, and determine the star-forming history. Optical spectroscopic surveys of an unbiased sample of candidate young …
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Laboratory Experiments of High-Energy-Density Shocks in Magnetized Supersonic Plasma Flows
… radiating shocks. Some examples include extrastellar jets from radio galaxies, relativistic jets from quasars and blazars, Herbig-Haro jets from Young Stellar Objects, and shocks in core-collapse supernovae and supernova remnants. In this study, we mimic these extreme astrophysical …
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Understanding the Earliest Stages of High-mass Star Formation
… study of the W3 GMC comprises an analysis of the young stellar objects (YSO), the regions currently hosting on-going high-mass star formation, the environment, history, and compact source population. Spitzer data were used to identify, classify, and investigate the clustering properties of the YSO …
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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
… 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 formation pathway is limited by existing data that do not combine angular resolution needed to …
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Star Formation in OB Associations and Clusters
… examined. We used the resolved massive stars and young stellar objects (YSOs) in N 44 to study star formation at both levels with extended coverage in space and time. Our study of massive stars showed that the present-day mass functions (PDMFs) of four star formation regions do not have obvious …
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Development of an automated alignment system for the Magdalena Ridge Observatory Interferometer
… complete, it will study active galactic nuclei, young stellar objects and mass transfer in dynamical systems at visible and near infrared wavelengths with sub-milliarcsecond angular resolution. The facility will gradually grow to include ten relocatable 1.4 metre diameter unit telescopes with …
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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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SHEDDING NEW LIGHT ON OLD DATA: FINDING NEW RESULTS FOR EXOPLANET SCIENCE IN ARCHIVAL DATA
… water. In Chapter 4 I discuss my work with the stellar spectra from WFC3, which utilise the sub-pixel shifts in target position to oversample the spectra and increase the resolution. I have compared these exoplanet host stellar spectra with stellar models to investigate how well stellar …
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Interpreting the 10um astronomical silicate feature
… Cyg 0B2 no. 12 and towards field and embedded objects in the Taurus Molecular Cloud (TMC) were obtained with CGS3 at the United Kingdom Infrared Telescope (UKIRT). Cold molecular-cloud silicates are sampled in quiescent lines of sight towards the field stars Taurus-Elias 16 and Elias 13, whilst …
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A COMPARISON OF STAR FORMATION WITHIN THE GALACTIC CENTRE AND GALACTIC DISC
… to be untouched by the disruptive effects of stellar feedback, such that the natal conditions of the gas – e.g. kinematics and chemistry – are not destroyed. Quiescent regions that are expected to form low-mass stars have been well studied over the past few decades, and the general process of …
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