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 8 of 8 for “"Pre-main sequence stars"”.
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Lithium and age of pre-main sequence stars
… sulla base della dinamica, quindi senza precedenti ipotesi. La medesima metallicità e età delle componenti di un sistema binario rappresenta un forte vincolo nella determinazione delle soluzioni. In una prima fase ho svolto una campagna spettroscopica allo scopo di ottenere dati …
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Coronal properties of pre-main sequence stars in the Orion Trapezium Cluster
Most of the young stars in the Orion Trapezium Cluster are much more peculiar in X-rays than expected, considering their structure, environment, and age. Highly resolved X-ray spectra provide many more details in order to study these peculiarities, specifically with respect to abundances and …
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Spectroscopic and spectro-astrometric analysis of T Tauri Stars
… analogs to the early solar system called T Tauri stars. These objects are low-mass, pre-main sequence stars surrounded by circumstellar disks of material from which planets are believed to form. We present high-resolution, near-infrared spectroscopic data for the T Tauri stars DR Tau and AA Tau …
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High-resolution studies of protoplanetary disks
This work presents a multi-wavelength search (near-IR, mid-IR, mm) for previously unknown circumstellar disks and a study of those disk candidate objects which are not yet well characterised in the literature. 22 candidate stars, most of these constituting known exoplanet systems, were examined for …
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Dust in circumstellar disks
This thesis presents observational and theoretical studies of the size and spatial distribution of dust particles in circumstellar disks. Using millimetre interferometric observations of optically thick disks around T Tauri stars, I provide conclusive evidence for the presence of millimetre- to …
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A technique for astronomical spectroscopy with a multi-aperture telescope
… its manipulation, display and storage presented a major research effort which were largely overcome by the use of cheap, digital micro-computers. To achieve rapid and flexible data handling the i.E.E.E. bus was used as the communication medium between control and data collecting …
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Optical spectroscopic studies of two star forming regions
… surveys of an unbiased sample of candidate young stars have been completed. Optical images taken in different photometric bands were used to create color-magnitude diagrams from which sources were selected for spectroscopic observation. In combination with published data, 135 association members …
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The Inner Gaseous Disks Of Herbig Be Stars
Herbig Ae/Be stars are intermediate mass (~2 to 20Msun) pre-main sequence stars that inherit a circumstellar disk of dust and gas from their formation phase. The region of this disk closest to the star is entirely gaseous because dust evaporates at the high temperatures there, and this gaseous …