Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Paul R. Shapiro. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2002. / Includes bibliographical references. Also available on microfiche.

Paper discusses the expected uncertainty of orbital parameters of binary stars as measured by the space-based gravitational wave observatory LISA (Laser Interferometer Space Antenna) and how the inclusion of spin in the model of the binary stars affects the uncertainty. The uncertainties are found by calculating the received gravitational wave from a binary pair and then performing a linear least-squares parameter estimation. The case of a 1500 solar mass black hole that is 20 years from coalescing with a 1000 solar mass black hole--both of which are 50 x 10^6 light years away--is analyzed, and the results show that the inclusion of spin has a negligible effect upon the angular resolution of LISA but can increase the accuracy in mass and distance measurements by factors of 15 and 65, respectively.

The potential for luminosity functions (LFs) of post-turnoff stars to constrain basic cluster parameters such as age, metallicity, and helium abundance is examined in this dissertation. A review of the published LFs for the globular cluster (GC) M92 suggests that the morphology of the transition from the main sequence to the red giant branch (RGB) is sensitive to these parameters. In particular, a small bump in this region may provide an important age discriminant for GCs. A significant deficiency in the number of stars over a 2 mag interval, just below the turnoff, remains unexplained. A method of interpolating isochrones and LFs accurately from evolutionary sequences, from the lower main sequence to the RGB tip, is discussed. The interpolation scheme is based on primary interpolation points which are identified by the behaviour of the derivative [special characters omitted] along an evolutionary sequence. New BV CCD observations, calibrated with Landolt and Graham standard stars, for the old open cluster NGC 2243 and for the bright stars in the GCs NGC 288 and NGC 7099 are presented. The colour magnitude diagram (CMD) of NGC 2243 contains a strong binary star component. Comparisons with the fiducial sequences of the GC 47 Tuc (Hesser et al. 1987) indicate that the two clusters have similar abundances, while comparisons with the new oxygen-enhanced isochrones (Bergbusch & VandenBerg 1992) suggest that NGC 2243 has an age of 4-5 Gyr, and a metallicity [special characters omitted]. The morphology of both the CMD and the LF through the turnoff region cannot be attributed to the merging of the binary and single star sequences, but convective overshooting works in the correct sense to account for the differences between the isochrones and the CMD. For NGC 288 and NGC 7099, excellent overall consistency among the Zero-Age Horizontal Branch, isochrone, and LF fits is obtained for cluster ages of 14-16 Gyr. The manifestation of the transition bump in NGC 288's LF provides a particularly strong constraint on the age, since this feature becomes more prominent as the metallicity increases. R-method helium abundance estimates give Y ≈ 0.23 for NGC 288 and Y ≈ 0.31 for NGC 7099. The 2nd parameter problem is discussed in light of these results. The RGB bump, present in canonical LFs, is only weakly identified in the cumulative LF (CLF) of NGC 288, and may not be present at all in NGC 7099's CLF. However, the brightest RGB stars in both clusters are found within ≈ 0.2 mag of the RGB tip predicted by the oxygen-enhanced models. / Graduate

No description available.

The underlying theme of this thesis is the application of electronography to the study of stars in globular clusters through the use of both broad and intermediate-band photometric systems. Introductions to both the study of globular clusters and to the use of electronography are given in Chapter 1. In Chapters 2 and 3 observations based upon electronographic exposures are presented for two little-studied clusters, NGC 5053 and NGC 6366. Both are loose, sparsely populated clusters but despite their similarity in appearance, the photometry shows that NGC 5053 is an unreddened, metal-poor globular, while NGC 6366 is found to be a highly reddened metal-rich cluster. One variable star in NGC 6366 is shown to be an a-type RR Lyrae - an unusual occurrence in a cluster of high metallicity. Chapter 4 describes developments in the reduction of stellar electronographs made by the author. An automatic method of fitting Gaussian profiles to the density volumes is shown to produce photometry as accurate and linear as previous manual techniques, but with a much increased efficiency. This work is extended to investigate the use of more flexible profiles which are then shown to be useful for allowing photometry of crowded images. Finally, an application of the Gaussian profile fitting routines to photographic stellar photometry is discussed. Chapter 5 reports the use of this reduction scheme on photographic plates of the globular cluster M 15. Using the David Dunlap Observatory (DDO) intermediate-band photometric system, cluster members are easily distinguished from foreground dwarfs. Chapter 6 describes the results of a programme of DDO electronography of the globular clusters M 5 and M 13. An accuracy of 0.03 is obtained for the DDO colours which, although comparable with some earlier photoelectric work, shows that, with the observational and reduction techniques employed, electronographic stellar photometry has not yet attained its potential as two-dimensional photoelectric photometry.

Observations of four massive x-ray binary stars are presented, based on data accumulated between February 1989 and August 1991. Using modern techniques of spectroscopic data analysis, velocity curves are derived for three of these systems. Two of these curves (SMC X-1, QV Nor) yield very precise mass estimates for the component stars, while the third (Cen X-3) offers a constraint on the possible masses. The fourth system (X Per) is not shown to exhibit periodic variations, despite an extensive study conducted over more than two years. For the two systems that yielded precise masses, the component neutron stars are shown to lie within the theoretical mass range based on theories of their formation via the supernova explosion of a helium star in a close binary system. This is a marked improvement on previous studies where both stars had estimated masses which lay well outside of the expected range. The derivation of these masses incorporates the use of non-Keplerian velocity corrections, arising from the non-spherical, asymmetrically illuminated primary stars. A study of the line profiles showed that the temperatures around both primary stars were consistent with the parameters in these calculations. For the third system, the inaccuracy of the published ephemeris resulted in a lack of observations at the times of maximum and minimum velocity. The semi-amplitude is thus not well constrained, but it is shown that the observations are consistent with the assumption of a normal mass neutron star secondary. The system is shown to have undergone a gradual decrease in its orbital period which follows a parabolic trend, suggesting substantial mass-transfer. For the fourth system, a periodicity analysis of 130 spectroscopic velocity measurements of a Be star, via Fouriergram and string-length techniques, failed to highlight any strong periodicity. The scatter in the data appears larger than would be expected for a non-variable B star. The absence of periodic velocity variations at the expected period is discussed in terms of the binarity (or otherwise) of the Be star. A transition from Be to shell-star or ordinary B star phase occurred during the study, which is not evident from the spectral variations observed in the blue.

Spectroscopic and photometric observations of eight contact/near-contact binaries are presented and analysed. Spectroscopic observations were obtained at 4200 Å (radial velocity spectra) and 6563 Å (hydrogen-alpha line profiles). New photometric observations were obtained at visual and infrared wavelengths, and other previously published light curves are also re-analysed. Absolute dimensions have been obtained for five systems; TY Boo, VW Boo, BX And, SS Ari and AG Vir, and their evolutionary positions discussed. Four of the systems are found to be in marginal but poor thermal contact, exhibiting regions of apparent "excess luminosity" in their light curves. A qualitative analysis of these "hot spot" regions has been attempted for the first time using spot models now incorporated into a light curve synthesis programme. Substantial time for this project was awarded on telescopes funded by the United Kingdom Science and Engineering Research Council (SERC), comprising 14 nights at the Issac Newton Telescope (INT) on La Palma, and 4 nights at the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea. Additional observations were made during an 8 night commissioning run on the Jacobus Kapteyn Telescope (JKT) on La Palma, and extensive observations were made with the Twin Photometric Telescope (TPT) at St Andrews University Observatory between 1985 and 1989. These resulted in over 100 spectra at 4200 Å and over 50 spectra at 6563 Å (INT and JKT observations), over 300 infrared photometric observations (UKIRT), and over 3500 visual photometric observations (TPT). Of the five systems analysed in detail in this work, TY Boo appears to be a normal shallow-contact W-type system. Both VW Boo and BX And exhibit regions of "excess luminosity" around the ingress and egress of secondary minimum which are well modelled by a warm spot on the cooler component sitting symmetrically around the neck joining the pair. Such a phenomenon may be expected to arise naturally in systems which have come into contact but are not yet/currently in thermal contact, exhibiting a temperature difference between the components. BXAnd like other B-type systems seems to be reaching this contact state for the first time, but the position of VW Boo is uncertain, and whilst evidence that it could be in the "broken contact" state predicted by the TRO Theory is far from conclusive, its lower orbital angular momentum clearly marks the system as worthy of further study. SS Ari and AG Vir exhibit light curves with unequal quadrature heights. Attempts to treat the higher quadrature as a region of "excess luminosity" due to an energy transfer "warm spot" does not however provide a good model of this phenomenon. Since invoking a dark starspot model also does not provide a good explanation for such systems, it may be that this form of light curve distortion is due to an entirely different form of distorting surface phenomenon. Like BX And, AG Vir appears to be just reaching contact for the first time, but like VW Boo, the slightly lower angular momentum of SS Ari warrants further study.