Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Astronomy

Supervisor

C. E. Jones

Abstract

A series of B-emission (Be) stars was observed interferometrically and numerically modelled to be consistent with the observations. Uniform geometrical disks were used to make first-order inferences about the configuration of the disk systems’ extended structures and their extent on the sky. Later, the Bedisk-Beray-2dDFTpipeline was used to make sophisticated non-local thermodynamic equilibrium (LTE) calculations of the conditions within the disks. In the first instance, sixteen stars were observed in the near-infrared (K-band, 2.2 micron) with the Palomar Testbed Interferometer (PTI). The Bedisk portion of the pipeline was used to model disk temperature and density structures for B0, B2, B5 and B8 spectral types, which were then compared to observations of stars most closely matching one of these types. This is the first time such an extensive set of Be stars observed with long-baseline interferometry has been analyzed with self-consistent non-LTE numerical disk models. The subsequent studies were focussed specifically on 48 Per and Per. Both stars were observed with the Navy Precision Optical Interferometer (NPOI) in 2006-November and December, with additional observations taken of Per in 2010-January and 2011-February. H-alpha spectra for both stars were recorded contemporaneously with the 2006 NPOI observations. Models were calculated with the full Bedisk-Beray-2dDFT pipeline to produce spectral line profiles and synthetic images which were constrained via direct comparison with published studies including Quirrenbach et al. (1997) and Delaa et al. (2011). The results of these comparisons were generally favourable. The pipeline output was also used to estimate the mass of the 48 Per disk and to compute spectral energy distributions which were compared with those in Touhami et al. (2010). Although 48 Per is largely quiescent, psi Per shows considerable variability over the epochs in which it was observed. The use of interferometry to probe the effects of variability on the extended structure is novel.

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