In this thesis I take a close look at the far-infrared radio - correlation, a puzzlingly persistent and tight relationship identified between the far-infrared and radio luminosities of star forming galaxies. Two disparate processes are attributed to this phenomenon. In the first, starlight from massive stars is reprocessed by dust to be re-emitted in the infrared and secondly, radio emission in the form of synchrotron radiation originating in shocks driven by these same high mass stars as they end their lives as supernovae. Cosmic ray electrons are accelerated by these shocks, their paths subsequently spiralling in their host galaxies magnetic fields, produce a continuum of synchrotron radiation. I investigate this far-infrared radio correlation for a large sample of IRAS galaxies and compare my results to previous studies. I look at the effect of peak galaxy dust temperature on the correlation, dividing my sample into ‘warm' and ‘cool' bins and find a lower flux ratio in the warm sample. The correlation at low radio frequencies is tested, probing the constancy of the dominant synchrotron radiation where absorption or other effects are expected to lead to a divergence from the linear continuum spectrum. Finally I look at a smaller sample of galaxies in the ELAIS-N1 field using HerMES and GMRT data to investigate the correlation to higher redshifts. The interest and rational for investigating this correlation is its evident link to star formation. Any deviation for example will imply an evolution in one or both of these processes which are closely linked to star formation. With the advent of new dedicated low frequency array radio telescopes such as LOFAR it is increasingly necessary to trust the correlation at these longer wavelengths if observational data is to be used as a reliable predictive tool in the study of star formation.

The formation and growth of galaxies through star formation is an unsolved problem in astrophysics. Emission from galaxies in the far-infrared is known to be strongly correlated with obscured star formation and makes up a significant fraction of the cosmic infrared background. The Herschel Space Observatory was designed to cover the wavelengths where this background peaks and gave an unprecedented view of the Universe at this part of the electromagnetic spectrum. This thesis uses observations conducted for the Herschel Multi-tiered Extragalactic Survey (HerMES) by the Herschel Space Observatory's SPIRE instrument to catalogue sources of far infrared emission at 250μm, 350μm and 500μm which will allow models of galaxy evolution to be constrained. Source detection and extraction is performed with both blind and prior-driven algorithms on two newly constructed maps and, for the first time, on the largest of the HerMES' maps, HeLMS. Modifications are made to the algorithms to compensate for cirrus contamination. The accuracy and completeness of both algorithms are assessed and compared. In addition, emission from a galaxy across the three SPIRE bands is known to be strongly correlated. The extent of the covariance between the SPIRE images is explored using Principal Component Analysis, finding that up to 95% of the variance in the SPIRE maps can be explained by one linear combination of the three SPIRE bands. This new projection of data could allow previously unfeasible multi-dimensional probability of deflection analyses to be performed through a reduction of the data dimensionality. Looking forward, the Herschel Extragalactic Legacy Project (HELP) will be using Herschel observations from both HerMES and the H-ATLAS collaboration to create homogenous, multi-wavelength data products. In the final chapter, a comparison between datasets to test the homogeneity was undertaken, leading to a preliminary recalculation of the HerMES angular correlation function, a result that has been in contention between collaborations. Catalogues created as part of this thesis are available at hedam.lam.fr/HerMES/.

The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in 2008 and completed in 2013, the project was supported by three Large Program allocations, as well as various programmes initiated by independent principal investigators, and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada–France–Hawaii Telescope, Narval at the Télescope Bernard Lyot and HARPSpol at the European Southern Observatory La Silla 3.6 m telescope, making MiMeS by far the largest systematic investigation of massive star magnetism ever undertaken. In this paper, the first in a series reporting the general results of the survey, we introduce the scientific motivation and goals, describe the sample of targets, review the instrumentation and observational techniques used, explain the exposure time calculation designed to provide sensitivity to surface dipole fields above approximately 100 G, discuss the polarimetric performance, stability and uncertainty of the instrumentation, and summarize the previous and forthcoming publications.

This report will first give a brief background on asymptotic giant branch (AGB) stars and the characteristics that make them interesting to study. Some methods and tools used in the field are then introduced, before the photometric variability of these stars is investigated. This is achieved by using data from dynamical models of AGB stars with differing chemical abundances. The R, J and K bands of the UBVRI system are specifcally investigated to explore whether these are good candidates for AGB photometric and spectroscopic research. Lastly, the molecular features at these wavelengths are investigated to understand the impact that they have on the photometric variability during the pulsation cycle and which molecules are most prominent in this.

Observations were made of 309 binary systems between RA 17h - 07h and Dec -70 degrees to -60 degrees. The images were calibrated against pairs measured for CCD astometry. Measurements were made of separations, position angles and differential magnitudes. Uncertainties in position angle and separation were 7.8o/p and 0.16 arcseconds respectively. The position angles, separations and differential V magnitudes were compared with WDS figures. It was determined that only 29% _+ 5% of the observed pairs had undergone significant movement since the last previous measurement, which agrees with the results of a survey of the WDS. A statistical study of 1q77 pairs found that the spread of calculated separations agreed with those found by other authors, while the distribution of periods, while falling within the range(s) calculated by other authors, were significantly longer. A short-arc fitting program was tested using data derived from the published orbit of Centauri before being applied to seven observed pairs. Orbits could be calculated for six of the seven pairs. For four of these pairs the observed movement may be due to proper motion rather than orbital motion / Master of Science (Hons)

No description available.

Thesis (Ph. D.)--University of Chicago, Dept. of Astronomy and Astrophysics, 2001. / Includes bibliographical references. Also available on the Internet.

Inaug.-diss.-Göttingen. / Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 132-136).

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 110-114).