The Evolution of Nova Remnants

In this review I concentrate on describing the physical characteristics and evolution of the nebular remnants of classical novae. I also refer as appropriate to the relationship between the central binary and the ejected nebula, particularly in terms of remnant shaping. Evidence for remnant structure in the spectra of unresolved novae is reviewed before moving on to discuss resolved remnants in the radio and optical domains. As cited in the published literature, a total of 5 remnants have now been resolved in the radio and 44 in the optical. This represents a significant increase since the time of the last conference. We have also made great strides in understanding the relationship of remnant shape to the evolution of the outburst and the properties of the central binary. The results of various models are presented. Finally, I briefly describe new results relating to the idiosyncratic remnant of GK Per (1901) which help to explain the apparently unique nature of the evolving ejecta before concluding with a discussion of outstanding problems and prospects for future work.Comment: 12 pages, 8 figures. Invited review in the Proceedings of the Conference "Classical Nova Explosions" (Sitges, May 2002), M. Hernanz and J. Jose eds., published by the American Institute of Physic

Classical and Recurrent Nova Outbursts

Over the last 40 years, multi-frequency observations, coupled with advances in theoretical modelling, have led to a much fuller understanding of the nova phenomenon. Here I give a brief review of the current state of knowledge of Classical and Recurrent Novae including their central systems; the causes and consequences of their outbursts; sub-types, and possible relationships to Type Ia Supernovae. Particular attention is paid to the Recurrent Nova RS Ophiuchi as it shows a wealth of phenomena associated with its 2006 outburst. Finally, some open questions and avenues for future work are summarised.Comment: 10 pages, 2 figures. Review paper submitted to the proceedings of the 11th Asian-Pacific Regional IAU Meeting 2011, NARIT Conference Series, Vol. 1, 2012. S. Komonjinda, Y. Kovalev, and D. Ruffolo, ed

Statistics of Quasars Multiply Imaged by Galaxy Clusters

We compute the expected number of quasars multiply imaged by cluster size dark halos for current wide field quasar surveys by carrying out a large ensemble of ray tracing simulations through clusters from a cosmological N-body simulation of the LCDM cosmology. Our calculation predicts ~ 4 quasar lenses with splittings theta > 10" in the SDSS spectroscopic quasar sample, consistent with the recent discovery of the wide separation lens SDSSJ1004+4112 which has theta=14.6". The SDSS faint photometric quasar survey will contain ~12 multiply imaged quasars with splittings theta > 10". Of these, ~ 2 will be lenses with separations theta > 30", and ~ 2 will be at high redshift (z ~ 4).Comment: 6 pages, 3 Figures, submitted to Ap

Flickering variability of T Coronae Borealis

We present electro-photometric UBV and high-speed U-band flickering observations of the recurrent nova T CrB during a period when its U brightness varies by more than 2 mag. The V band is dominated by the ellipsoidal variability of the red giant, however, the variability of the hot component also causes 0.15 mag variations in V. We define a set of parameters which characterise the flickering. The Fourier spectra of all 27 nights are similar to each other. The power spectral density of the variations has a power law component (f^{-1.46} on average). We do not detect a dependence of the Fourier spectra and autocorrelation function on the brightness of the object. Having subtracted the contribution of the red giant, we show that the flickering amplitude correlates with the average flux of the accreting component. A comparison with CH Cyg and MWC 560 indicates that the flickering of T CrB is more stable (at least during the time of our observations), than that in the jet-ejecting symbiotic stars. The data are available in electronic form from the authors.Comment: 8 pages, 6 figures, 2 tables, accepted for publication in MNRA

Liverpool Telescope Optical Photometry Following the 2006 Outburst of RS Ophiuchi

We present a preliminary report on the broadband optical photometry of the 2006 outburst of the recurrent nova RS Ophiuchi. These data were obtained using the robotic 2m Liverpool Telescope and cover the outburst from day 27 through day 548.Comment: 3 pages, 2 figures, to appear in ASP conference proceedings Volume 401 "RS Ophiuchi (2006) and the recurrent nova phenomenon

On the Evolution of the Late-time {\it Hubble Space Telescope} Imaging of the Outburst of the Recurrent Nova RS Ophiuchi (2006)

We modelled the late-time {\it Hubble Space Telescope} imaging of RS Ophiuchi with models from Ribeiro et al. (2009), which at the time due to the unknown availability of simultaneous ground-based spectroscopy left some open questions as to the evolution of the expanding nebular from the early to the late time observations. Initial emission line identifications suggest that no forbidden lines are present in the spectra and that the emission lines arising in the region of the WFPC2 F502N images are due to N{\sc ii} and He{\sc i} + Fe{\sc ii}. The best model fit to the spectrum is one where the outer faster moving material expands linearly with time while the inner over-density material either suffered some deceleration or did not change in physical size. The origin of this inner over-density requires further exploration.Comment: 6 pages, 3 figures, to appear in Stella Novae: Past and Future Decades, P. A. Woudt & V. A. R. M. Ribeiro (eds), ASPCS 49

The Evolution of Nova Ejecta

In this paper I review the basic parameters of Classical Novae and then move on to describe the evolution of their ejected envelopes. The early shaping of the remnant, thought to be a consequence of a common envelope phase, and with analogies to what may occur in PNe with binary star nuclei, is then described. Finally, the curious case of Nova GK Persei (1901) and its potential to aid our understanding of both nova and long-term PN evolution is discussed.Comment: To be submitted to the Proceedings of Asymmetrical Planetary Nebulae III, eds. M. Meixner, J. H. Kastner, and N. Soker, ASP Conf. Series; 7 pages, 4 figures; Draft: will be revised according to comments by readers and other papers submitted to the Proceeding

High Spatial Resolution Optical and Radio Imagery of the Circumbinary Environment

In this review, I concentrate on describing observations of spatially resolved emission in symbiotic stars at sub-arcsecond scales. In some of the closer objects, the highest resolutions discussed here correspond to linear dimensions similar to the supposed binary separation. A total of 17 stars well accepted as symbiotics are now observed to show sub-arcsecond structure, almost twice the number at the time of the last review in 1987. Furthermore, we now have access to HST imagery to add to radio interferometry. From such observations we can derive fundamental parameters of the central systems, investigate the variation of physical parameters across the resolved nebulae and probe the physical mechanisms of mass loss and interactions between ejecta and the circumstellar medium. Suggestions for future work are made and the potential of new facilities in both the radio and optical domains is described. This review complements that by Corradi (this volume) which mainly considers the larger scale emission from the ionized nebulae of these objects.Comment: 17 pages, 9 figures, to appear in "Symbiotic Stars Probing Stellar Evolution", eds. R. L. M. Corradi, J. Mikolajewska, and T. J. Mahoney, ASP Conference Serie

Spectroscopic and Photometric Development of T Pyxidis (2011) from 0.8 to 250 Days After Discovery

We investigated the optical light curve of T Pyx during its 2011 outburst through compiling a database of SMEI and AAVSO observations. The SMEI light curve, providing unprecedented detail with high cadence data during t=1.5-49 days post-discovery, was divided into four phases based on the idealised nova optical light curve; the initial rise, the pre-maximum halt (or the 'plateau'), the final rise, and the early decline. Variation in the SMEI light curve reveals a strongly detected period of 1.44\pm0.04 days before the visual maximum. The spectra from the LT and SMARTS telescopes were investigated during t=0.8-80.7 and 155.1-249.9 days. The nova was observed very early in its rise and a distinct high velocity ejection phase was evident. A marked drop and then gradual increase in derived ejection velocities were present. Here we propose two different stages of mass loss, a short-lived phase occurring immediately after outburst followed by a more steadily evolving and higher mass loss phase. The overall spectral development follows that typical of a Classical Nova and comparison to the photometric behaviour reveals consistencies with the simple evolving pseudo-photosphere model of the nova outburst. The optical spectra are also compared to X-ray and radio light curves. Weak [Fe X] 6375A emission was marginally detected before the rise in X-ray emission. The middle of the plateau in the X-ray light curve is coincident with the appearance of high ionization species detected in optical spectra and the peak of the high frequency radio flux.Comment: 6 pages, 4 figure

On the M31 Nova Progenitor Population

We present a survey of M31 novae in quiescence. This is the first catalogue of extragalactic systems in quiescence and contains 37 spectroscopically confirmed novae from 2006 to 2013. We used Liverpool Telescope and Faulkes Telescope North images taken during outburst to identify accurate positions for each system. These positions were then transformed to archival Hubble Space Telescope (HST) images and we performed photometry on any resolvable source that was consistent with the transformed positions. As red giants in M31 will be resolvable in the HST images, we can detect systems with red giant secondaries. There are only a few confirmed examples of such systems in our Galaxy (e.g. RS Oph and T CrB). However, we find a much higher portion of the nova population in M31 may contain red giant secondaries. For some novae, coincident HST images had been taken when the nova was still fading, allowing us to produce light curves that go fainter than is possible to achieve for most extragalactic systems. Finally, we compare the M31 and Galactic quiescent nova populations.Comment: 6 pages, 3 figures, to appear in Stella Novae: Future and Past Decades, P. A. Woudt & V. A. R. M. Ribeiro (eds), ASPC