SW Sex stars, old novae, and the evolution of cataclysmic variables

The population of cataclysmic variables with orbital periods right above the period gap are dominated by systems with extremely high mass transfer rates, the so-called SW Sextantis stars. On the other hand, some old novae in this period range which are expected to show high mass transfer rate instead show photometric and/or spectroscopic resemblance to low mass transfer systems like dwarf novae. We discuss them as candidates for so-called hibernating systems, CVs that changed their mass transfer behaviour due to a previously experienced nova outburst. This paper is designed to provide input for further research and discussion as the results as such are still very preliminary.Comment: 4 pages. conference: The Golden Age of Cataclysmic Variables and Related Objects II, Palermo 2013. Accepted for publication in Acta Polytechnic

Life after eruption, II : the eclipsing old nova V728 Scorpii

The old nova V728 Sco has been recently recovered via photometric and spectroscopic observations, 150 yr after the nova eruption. The spectral properties pointed to a high-inclination system with a comparatively low mass-transfer rate. In this paper, we show that the object is an eclipsing system with an orbital period of 3.32 h. It has enhanced long-term variability that can be interpreted as `stunted' dwarf-nova-type outbursts. Using the ingress and egress times of the eclipsed components we calculate the radius of the central object. The latter turns out to be significantly larger than a white dwarf and we identify it with a hot inner disc. The implications for models on the behaviour of post-novae are discussed

The pre-cataclysmic variable, LTT 560

Aims. System parameters of the object LTT560 are determined in order to clarify its nature and evolutionary status. Methods. We apply time-series photometry to reveal orbital modulations of the light curve, time-series spectroscopy to measure radial velocities of features from both the primary and the secondary star, and flux-calibrated spectroscopy to derive temperatures of both components. Results. We find that LTT 560 is composed of a low temperature (T ∼ 7500 K) DA white dwarf as the primary and an M5.5±1 mainsequence star as the secondary component. The current orbital period is Porb = 3.54(07) h.We derive a mass ratio Msec/Mwd = 0.36(03) and estimate the distance to d = 25–40 pc. Long-term variation of the orbital light curve and an additional Hα emission component on the white dwarf indicate activity in the system, probably in the form of flaring and/or accretion events

Unveiling the 3D structure of nova shells with MUSE -- The case of RR Pic

Nova eruptions occur in cataclysmic variables when enough material has been accreted onto the surface of the white dwarf primary. As a consequence, the material that has been accumulated until then is expelled into the interstellar medium, forming an expanding nova shell around the system. Understanding the physical process that shapes the morphology of nova shells is essential to fully comprehend how the ejection mechanism operates during nova eruptions. Because of its closeness and age, the nova shell around the classical nova RR Pic (Nova Pic 1925) is an ideal target for studying the evolving morphology of nova shells. In this work, we present an IFS study of the RR Pic nova shell, with a particular emphasis on the extraction of the 3D morphology of the shell. The nova shell was observed by the Multi-Unit Spectroscopic Explorer (MUSE) instrument placed at the ESO-VLT. The MUSE datacube confirms the presence of the nova shell in H$\rm\alpha$, H$\rm\beta$ and [OIII], and very faintly in [NII]. A comparison with previous observations suggests that the shell continues in its free-expansion phase but with the different parts of the shell apparently expanding at different rates. The data analysis corroborates the previous vision that the shell is composed of an equatorial ring and polar filaments. At the same time, the new data also reveal that [OIII] is confined in gaps located in the tropical regions of the shell where no Hydrogen is observed. The flux measurements indicate that ~99% of the shell flux is confined to the equatorial ring, while the polar filaments show a flux asymmetry between the NE and SW filaments. We have estimated the mass of the shell to be ~5x10$^{-5}$M$_\odot$. From the analysis of the 3D-extracted data, we determine that the ring structure extends ~8,000 au from the central binary, and has a position angle of ~155 deg and an inclination of ~74 deg.Comment: 18 pages, 12 figures. Accepted for publication in A&A. Waiting for production offic

Structure of the accretion flow of IX Velorum as revealed by high-resolution spectroscopy

Context: Several high-mass transfer cataclysmic variables show evidence for outflow from the system, which could play an important role in their evolution. We investigate the system IX Vel, which was proposed to show similar characteristics. Aims: We study the structure of the IX Vel system, particularly the structure of its accretion flow and accretion disc. Methods: We use high-resolution time-resolved spectroscopy to construct radial velocity curves of the components in IX Vel, we compute Doppler maps of the system which we use to estimate the temperature distribution maps. Results: We improve the spectroscopic ephemeris of the system and its orbital period P_orb = 0.19392793(3) d. We construct Doppler maps of the system based on hydrogen and helium emission lines and the Bowen blend. The maps show features corresponding to the irradiated face of the secondary star, the outer rim of the accretion disc, and low-velocity components located outside the accretion disc and reaching towards L3. We constructed a temperature distribution map of the system using the Doppler maps of Balmer lines. Apart from the features found in the Doppler maps, the temperature distribution map shows a region of high temperature in the accretion disc connecting the expected position of a bright spot and the inner parts of the disc. Conclusions: We interpret the low-velocity emission found in the Doppler map as emission originating in the accretion disc wind and in an outflow region located in the vicinity of the third Lagrangian point L3. This makes IX Vel a member of the RW Sex class of Cataclysmic Variables