並列タイトル等Exploring high precision VLBI astrometry of hydroxyl and water masers to study late stellar evolution
学位博士(理学)
Doctor of Philosophy in Science
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This PhD thesis has two main topics: technical studies of VLBI astrometry at L-band and astrometric measurements of OH and H2O masers to study late stellar evolution. The technical studies focus on mitigating spatial systematic errors caused by the ionosphere, the bane of VLBI measurements at low-frequencies, which hinder the astrometric applicability of one of the best stellar tracers, 1.6 GHzOH masers. We need to figure out how to do precise astrometry of OH masers; doing this would make it possible to measure accurate distances to evolved stars with heavy dust shells and high mass loss rates, the lack of which impeded on the better understanding of stellar evolution for far too long. This work provides an overview of relative VLBI astrometry from the point of view of error analysis, then goes on to demonstrate new calibration and analysis methods to achieve high precision astrometry at L-band. Some OH maser parallaxes are also measured in the process, but their application to study stellar evolution is ongoing. Additionally, the first results related to H2O masers in the fast outflows of water fountain stars are also presented, with a focus on better understanding the evolutionary process between evolved stars and planetary nebulae.
コレクション（個別）国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
受理日（W3CDTF）2017-09-02T15:28:24+09:00
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