Transference of angular momentum by collective motions occurs even in an inviscid disc. Their results, plotted in the r n - £ diagram, are given in Figure 3. The observed large linear polarizations are greatly in excess of what is predicted for scattering in a disc and are therefore almost certainly interstellar. The evolution from optically thick envelope to optically thin shell has been followed in 0. The ordinate is magnitude difference from a comparison star.
These are minimum values of M d during outburst. When observed, the Hell A4686 and A4650 emissions are generally wider e. His computations of the M d -M v relationships offer a helpful first estimate for Af d from Afv that are an improvement over use of more restrictive relationships e. For Roche lobefilling secondaries the mean density is given by equations 2. As already noted, the boundary layer may emit as much radiation as the entire disc, so a significant amount of heating of the disc, and consequent departure from the temperature distribution specified in equation 2. Hell A4686 is occasionally seen in emission. It is clear that the fluxes do not continue to rise below A ~ 1300 A, as extrapolated 2.
From the lowest spectrum upwards these were obtained 1. The singular appearance of the lines in some of these high M A systems is accompanied by an absence of rotational disturbance at eclipse, which Williams 1989 interprets as implying a lack of any true disc-like structure - possibly non-disc accretion caused by a large magnetic field on the primary discussed in detail in Section 7. Solid curves show the predicted luminosities from reprocessing of soft X-rays and hard X-rays. The Osaki model does not require such fine tuning. It appears, therefore, that optically thin emission is not adequate to account for the lines in low Af d systems.
Wood et al 1986; 3. The author then goes on to give an up-to-date review of both the observations at all wavelengths, and over all time-scales , the theories, the models of the structures and accretion processes believed to be involved. High temperatures are deduced Table 2. Its distance is not well determined, but lies in the range 0. Enhanced line emission originates from the region where the stream impacts the disc near the primary Section 2.
The results are also shown in Figure 3. However, as seen in Figure 3. The mean rate of decay is 0. The study of cataclysmic variables - interacting binary stars containing a white dwarf accreting from an orbiting companion - is undergoing an exciting renaissance, as it embraces observations at all wavelengths. Similar results are obtained for other novae V1370 Aql: 2. The implications of these have not been fully worked out. Results similar to Whitehurst's 1988a: Figure 2.
This timely volume provides the first comprehensive survey of cataclysmic variable stars, integrating theory and observation at all wavelengths and on all time-scales into a single, synthesised text. Weaker lines of other elements are difficult to detect because of the considerable line broadening from disc rotation. The left hand panel is from Hf3 emission and the right hand one from H7 emission. None appears in two-dimensional simulations Kaisig 1989a. As expected, there does not appear to be a dependence of Tn on P or b. The interpretation of this is discussed in Section 3.
Cataclysmic variables allow, in particular, the direct and detailed study of equilibrium and non-equilibrium accretion discs; in turn these developments also help in our understanding of X-ray binaries, black holes and active galactic nuclei. This constitutes indirect evidence for increased M 2 during the maximal development of a superoutburst. A sample result is shown in Figure 3. . It will become evident in Section 3. The observation of hard X-rays 5 d after the discovery of V838 Her Lloyd et al 1992 supports the latter view. It has long been supposed Kraft 1964b; Warner and van Citters 1974 that these may be in effect Z Cam stars in extended standstills.
An implication of equation 3. For example, it has become evident that accretion discs are one of the most commonly occurring structures - probably all stars form from disc-like configurations, with material left over to provide planetary systems. In optically thin discs the density in the emission-line forming regions can be far greater than in chromospheres. The dashed curve is an optically thin model; the light solid curve is Tylenda's 1981b model and the heavy solid curve is the model including a vertical density gradient. This timely volume provides the first comprehensive survey of cataclysmic variable stars, integrating theory and observation into a single, synthesised text. Furthermore, in the high state the 10-20 d low amplitude waves that occur in Z Cam stars at standstill Section 3. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.
The solid line represents equation 3. Penny was guided out of some of the software problems by generous help from Jacqui King. The temperature stratification is clearly very different from that of a stellar atmosphere. Similarly, soft X-rays are not observed from Z Cha Harlaftis et al 1992 , although hard X-rays were detected at quiescence by Einstein, and diminished during outburst Becker 1981. In their late development they often split into multiple narrow components. The author then goes on to give an up-to-date review of both the observations at all wavelengths, and over all time-scales , the theories, the models of the structures and accretion processes believed to be involved.
In the z direction, for a disc of negligible mass there is a hydrostatic balance between the pressure gradient and the z component of the primary's gravitational field: dP d 2. This timely volume provides the first comprehensive survey of cataclysmic variable stars, integrating theory and observation into a single, synthesised text. Two interpretations are offered: the 'cooler' continuum and the dips may indicate obscuration of the central part of the disc by vertical disc structure caused i by increased mass transfer, or ii by increased disc thickness in the regions of tidal dissipation Section 3. These show respectively typical principal phis diffuse-enhanced, Orion, and early nebular spectra. Z Cha Harlaftis et al 1992 measured 3. The global treatment confirms that the thermal limit cycle apparent in individual annuli can affect the whole disc.