Type of Document Dissertation Author Boyajian, Tabetha Suzanne URN etd-07172009-085607 Title Sizing Up the Stars Degree Ph.D. Department Physics and Astronomy Advisory Committee
Advisor Name Title Harold McAlister Committee Chair Douglas Gies Committee Member Gerard van Belle Committee Member Nikolaus Dietz Committee Member Paul Wiita Committee Member Russel White Committee Member Todd Henry Committee Member Keywords
- Interferometry
- Infrared
- Stellar Astronomy
- Fundamental Properties
- Effective Temperatures
- Stellar Radii
Date of Defense 2009-07-03 Availability unrestricted Abstract For the main part of this dissertation, I have executed a survey of nearby, main sequence A,F, and G-type stars with the CHARA Array, successfully measuring the angular diameters
of forty-four stars to better than 4% accuracy. The results of these observations also yield
empirical determinations of stellar linear radii and effective temperatures for the stars observed. In addition, these CHARA-determined temperatures, radii, and luminosities are fit to Yonsei-Yale isochrones to constrain the masses and ages of the stars. These quantities are
compared to the results found in Allende Prieto & Lambert (1999), Holmberg et al. (2007), and Takeda (2007), who indirectly determine these same properties by fitting models to observed photometry. I find that for most cases, the models underestimate the radius of the star by ~12%, while in turn they overestimate the effective temperature by ~ 1.5 - 4%, when compared to my directly measured values, with no apparent correlation to the star's metallicity or color index. These overestimated temperatures and underestimated radii in these works appear to cause an additional offset in the star's surface gravity measurements, which consequently yield higher masses and younger ages, in particular for stars with masses greater than ~ 1.3 M_sol. Alternatively, these quantities I measure are also compared to direct measurements from a large sample of eclipsing binary stars in Andersen (1991), and excellent agreement is seen within both data sets. Finally, a multi-parameter solution is found to fit color-temperature-metallicity values of the stars in this sample to provide a new calibration of the effective temperature scale for these types of stars. Published work in the field of stellar interferometry and optical spectroscopy of early-type stars are presented in Appendix D and E, respectively.
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