Available from UMI in association with The British Library. This thesis investigates the derivation and use of radial velocity curves of the secondary star to determine the component masses in cataclysmic variables. The first Chapter contains a brief review of these objects, especially their observational properties and possible evolutionary history. This highlights the uncertain state of understanding in this area and shows the need for accurate component masses. Chapter 2 is a critical review of the various methods which have been employed for mass determinations. The observational procedure and data reduction methods are covered in Chapter 3. CCD spectroscopy in the near infra-red is used to detect the spectrum of the secondary star in four systems (IP Peg, CN Ori, AM Her and U Gem), the first two of which are new detections. Radial velocity curves are produced by cross-correlation against the spectra of field stars. The observed spectra and radial velocity curves are reported in Chapter 4, together with the results of orbital fits to the curves. In three systems, a significant apparent eccentricity is detected. This may be due to irradiation of the inner face of the secondary or contamination by disc emission. To correct the orbital parameters for the effect of irradiation as well as tidal distortion and variation in surface gravity, a computer simulation of the secondary radial velocity curve was developed. Chapter 5 describes the assumptions and methods used to produce simulated spectra and derive radial velocity curves from them. Chapter 6 investigates the observational consequences of the above effects ruling out all but the reduction of line strength by irradiation as significant sources of eccentricity (contamination from the disc was not included). In Chapter 7 the corrections derived from the simulation are applied to the observations to produce masses for the four systems. Chapter 8 summarizes the main findings and suggests further work needed in this field.
- Pub Date:
- MASS DETERMINATION;
- Physics: Astronomy and Astrophysics