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No description available.

In this thesis, a hydrodynamical model for the 2006 outburst of the recurrent nova RS Ophiuchi (RS Oph) has been created. RS Oph is a close binary system comprising a white dwarf (WD) and a red giant (RG).

There are many questions about the properties of Classical Novae (CNe) that remain unanswered including their use as distance indicators and the possible relationship between the nova rate in a host galaxy and its Hubble type. To answer these and other questions the Liverpool Telescope Extragalactic Nova Survey, LENS, the largest dedicated CNe search, was undertaken to observe M81, M64 and NGC2403. LENS made of difference imaging techniques to increase the sensitivity of the survey and to allow variables to be sampled in areas of high surface brightness, which would not have been possible to observe using standard photometric techniques. Unidentified problems with the technique resulted in difference image lightcurves that were of insufficient quality to identify CNe within the dataset. Unsuccessful remedial action was undertaken to improve the quality of the difference image lightcurves.

Cataclysmic variables (CVs) are a class of closely interacting binary system that undergo mass transfer from a Roche lobe filling secondary star to a white dwarf primary star, usually via a gas stream and an accretion disc. A bright spot is formed where the gas stream meets the edge of the accretion disc. The light curves of CVs can be complex, with the accretion disc, white dwarf and bright spot all being eclipsed in rapid succession. When observed with time resolutions of the order of a few seconds, this eclipse structure allows the system parameters to be determined to a high degree of precision, with relatively few assumptions. In this thesis I present new, high-speed photometry of 20 eclipsing CVs. For 6 objects, I am able to determine the system parameters by fitting a parameterised model to the observed eclipse light curve (the photometric method). In addition, I perform an updated analysis of 11 CVs that were previously analysed by my group, bringing the total sample size of eclipsing CVs with precise mass determinations in this thesis to 17. I find the secondary stars in CVs are oversized in comparison to standard models. I show that this can be explained by either enhancing the mass-transfer rate, or by modifying the stellar physics of the secondary stars. Distinguishing between these two possibilities is not possible given the available data. I perform an independent check of the photometric method by deriving system parameters for one object using well known spectroscopic methods. The parameters derived are found to be consistent with the photometric method, thus supporting its accuracy and validity. Finally, I look at the infrared spectra of a short period CV. I am able to make a direct detection of the secondary star and place some constraints on the spectral type of the secondary star.

This thesis presents several case studies of disc winds from high-state cataclysmic variable stars, based on multi-wavelength time-series spectroscopy. The research presented here primarily focuses on three low-inclination, nova-like systems: RW Sextansis, V592 Cassiopeiae and BZ Camelopardalis. The aim was to derive and compare key spectral line diagnostics of the outflows, spanning a wide range of ionisation and excitation using (new) FUSE, HST, IUE and optical data. Analysis of the far-UV time-series of RW Sex reveals the wind to be highly variable but generally confined to between ~ -1000 and ~ 0 km/s for all ionisation states; no evidence of the wind at red-shifted velocities is found. This wind is modulated on the orbital period of the system and it is argued that the observed variability is due to changes in the blue-shifted absorption rather than a variable velocity emission. The Balmer profiles observed in the optical time-series of V592 Cas were found to be characterised by three components: a broad, shallow absorption trough, a narrow central emission and a blue-shifted absorption from the disc wind. The wind is also found to be modulated on the systems orbital period, although this modulation is slightly out of phase with the Balmer emission radial velocities. The wind of BZ Cam was found to behave very differently to that of RW Sex and V592 Cas. At times, it was seen (in the Balmer lines and some of the He I lines) to be extremely strong and variable but at other times is was seemingly not present; there was no evidence to suggest that it is modulated on the orbital or any other period. This study is an immense source of data on CV disc winds and importantly tries to parameterise three nova-like CVs to understand the similarities and differences between them and their winds.

Classical and Recurrent novae (CNe/RNe) are interacting close binary systems in which mass is transferred from a donor star to the surface of an accreting compact companion resulting in an outburst. Their study is important for our understanding of several branches of modern day astrophysics. The work presented in this thesis has focused on three particular topics: (i) Nova V458 Vulpeculae and its surrounding planetary nebula; (ii) Detailed nova light curves from the Solar Mass Ejection Imager (SMEI); and (iii) Vl721 Aquilae, an usually fast, luminous, and highly extinguished nova. A brief account is also given of more generalised work on novae in M31, and areas for future investigation are discussed. Nova V458 Vulpeculae is one of only two novae observed to lie within a planetary neb- ula (PN). Due to the outburst a light echo effect within the PN is experienced. Using Ha data taken over four years the illumination of the PN with time has been examined and a 3D visualisation obtained. Comparison of light echo data from PN models gen- erated with the morphokinematical modelling tool XS5 to observed PN light echo data indicate the presence of a PN with a bipolar external shell and an elliptical internal shell. Results have also confirmed that the PN is at a distance of 13 kpc. SMEI is a space-borne instrument based on-board the Coriolis satellite. It provides precision visible-light photometry of point sources down to 8th magnitude and near complete sky-map coverage at 102-minute cadence. Using SMEI data detailed light curves of novae have been obtained which offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the nova eruption normally not covered by ground-based observations. They have allowed the exploration of fun- damental parameters for individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt, the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust for- mation. The SME1 data archive undoubtedly holds a plethora of transient events and variable stars. A code designed to search for such events has been created and imple- mented on four years of SME1 data from one of its three cameras generating over 1500 variable objects, some of which were un-catalogued and are potentially very interest- mg. Finally data on the unusually fast and luminous Nova Vl721 Aquilae has been exam- ined. Pre-outburst N1R images from the 2MASS catalogue revealed the presence of a progenitor system, the absolute magnitudes and colours of which suggested the object to have a sub-giant secondary, and so belong to the U Sco class of RNe. Post-outburst spectra of the object revealed the presence of triple-peaked Ha and 01 profiles. Spec- tral fitting of these profiles indicated a high ejection velocity of 3350 km S-l. The triple-peaked nature of the Ha profile suggested that the accretion disc of the system is viewed face-on. This is supported by models created in XS5, which also indicated an axis ratio of rv 1.4 for the ejecta.