SYNOPSIS Included in this work, is a general historical overview of the development of astronomical knowledge in the West from the realms of Greek scholarship in classical times through to the Renaissance and the threshold of modern physics. The subject matter of both the Irish Tract and this review extends beyond the strict confines of astronomy, encompassing the physical sciences in general. The extent of astronomical knowledge in medieval Ireland is given specific attention with a review of scholarly works in Latin since the seventh century. This includes a number of specialist studies on astronomical topics and related cosmographical fields. Also included are numerous incidental references to astronomical matters from both Irish and Latin literature during the Middle Ages. Attention is devoted to the surviving manuscript copies of the Tract and the question of its sources, origin and purpose. A possible Dominican context for the compilation and dissemination of the Tract is considered. A detailed commentary of the technical content of each chapter is presented, together with reference to contemporary developments in the West and to the occasional clues as to the institutional, geographical and chronological origins of the Tract. A study of the technical terminology used by the Irish compiler is presented in detail. Reference is made both to earlier Irish terminology where appropriate, as well as to the limitations imposed by the fact that many of the scientific concepts were yet to attain clarity that came with the advent of Newtonian physics, Copernican astronomy and post-Colombian geography. The data entries on ms Stowe B are evaluated and compared with computer generated data of astronomical movements in the 14th and 15th centuries with a view to ascertaining the time of compilation of the Tract and its working life. A A revised English translation of the Tract is included in the appendices together with Maxwell Close's unpublished commentary to relevant portions. An Irish edition, closely following the ITS edition of 1914 is also included. Corruptions to the text are footnoted together with the likely run of the original text.

Thesis (Ph. D.)--Texas Christian University, 2007. / Title from dissertation title page (viewed Dec. 10, 2007). Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 1984. / Vita. Includes bibliographical references (leaves 141-142).

Thesis (Ph. D.)--University of California, San Diego, 1984. / Vita. Includes bibliographical references (leaves 141-142).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 110-113). Available also in a digital version from Dissertation Abstracts.

The post-asymptotic giant branch (post-AGB) phase is a short episode in the life of a star with mass between 0.8 to 8 M⊙. It comes after the AGB phase, and before the planetary nebula phase. A rapid change in many physical properties of a star is suggested to happen in this phase, for example the onset of jets. However, a lot of details are still unknown. In this thesis, three major problems are addressed: insufficient samples of post-AGB stars, identification of post-AGB stars, and the true status of a special class of objects called the “water fountains (WFs)”. WFs are evolved stars associated with high velocity collimated bipolar jets that can be traced by H2O maser emissions. For the first two problems, new searching criteria are introduced with two new maser surveys on oxygen-rich post-AGB stars. It is necessary to collect more samples of post-AGB stars for further studies. Nonetheless, there has been no systematic searching method because most of the post-AGB stars are dim in optical and near-infrared wavelengths, which increases the difficulty in identification. Maser thus becomes a good alternative tool. In the first survey which focused only on H2O masers, over 200 AGB or post-AGB star candidates have been selected and observed. Those candidates were mainly chosen by new colour criteria with the far-infrared AKARI data. In particular, four characteristic maser sources were found, and they are currently suggested as possible very young post-AGB stars. In the second survey, another 100 objects were observed in OH and/or H2O masers. Three possible high velocity objects were discovered, including a new rare member of WFs. The colour criteria are proved to be quite sensitive in distinguishing post-AGB stars from AGB stars or other types of objects, even though there are still some contamination from young stellar objects. A follow-up study shows that the Q-parameters are effective in isolating objects with spherical or aspherical envelopes, which are also useful in finding post-AGB stars. Regarding the third problem, one-dimensional radiative transfer models have been used to study the spectral energy distributions (SEDs) of all known WFs. Owing to the young dynamical ages of the WF jets, it has been suggested that WFs represent the very early post-AGB phase, when the circumstellar envelopes started to depart from spherical symmetry. However, it is shown from the present SED study that WFs in fact could have various form of morphologies, some of them are even spherical which resemble the AGB stars. It implies that WFs do not necessary belong to the very early post-AGB phase, and the present interpretation on the WF status may not be entirely correct. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy

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No description available.

SYNOPSIS Included in this work, is a general historical overview of the development of astronomical knowledge in the West from the realms of Greek scholarship in classical times through to the Renaissance and the threshold of modern physics. The subject matter of both the Irish Tract and this review extends beyond the strict confines of astronomy, encompassing the physical sciences in general. The extent of astronomical knowledge in medieval Ireland is given specific attention with a review of scholarly works in Latin since the seventh century. This includes a number of specialist studies on astronomical topics and related cosmographical fields. Also included are numerous incidental references to astronomical matters from both Irish and Latin literature during the Middle Ages. Attention is devoted to the surviving manuscript copies of the Tract and the question of its sources, origin and purpose. A possible Dominican context for the compilation and dissemination of the Tract is considered. A detailed commentary of the technical content of each chapter is presented, together with reference to contemporary developments in the West and to the occasional clues as to the institutional, geographical and chronological origins of the Tract. A study of the technical terminology used by the Irish compiler is presented in detail. Reference is made both to earlier Irish terminology where appropriate, as well as to the limitations imposed by the fact that many of the scientific concepts were yet to attain clarity that came with the advent of Newtonian physics, Copernican astronomy and post-Colombian geography. The data entries on ms Stowe B are evaluated and compared with computer generated data of astronomical movements in the 14th and 15th centuries with a view to ascertaining the time of compilation of the Tract and its working life. A A revised English translation of the Tract is included in the appendices together with Maxwell Close's unpublished commentary to relevant portions. An Irish edition, closely following the ITS edition of 1914 is also included. Corruptions to the text are footnoted together with the likely run of the original text.

Thesis (Ph. D.)--McMaster University, 2006. / Supervisor: William E. Harris.