SW Sex Stars Then and Now: A Review

SW Sextantis stars are a class of cataclysmic variables originally defined via certain peculiar properties that they all have in common. In this article, I review our knowledge of these stars and show the way from a phenomenological classification to a physical understanding of these systems. The fact that SW Sex stars accumulate at the upper edge of the period gap is discussed with respect to the secular evolution of cataclysmic variables.Comment: 14 pages, 12 figures, conference proceeding

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

SS433: Observation of the circumbinary disc and extraction of the system mass

The so-called "stationary" H-alpha line of SS433 is shown to consist of three components. A broad component is identified as emitted in that wind from the accretion disc which grows in speed with elevation above the plane of the disc. There are two narrow components, one permanently redshifted and the other permanently to the blue. These are remarkably steady in wavelength and must be emitted from a circumbinary ring, orbiting the centre of mass of the system rather than orbiting either the compact object or its companion: perhaps the inner rim of an excretion disc. The orbiting speed (approximately 200 km/s) of this ring material strongly favours a large mass for the enclosed system (around 40 solar masses), a large mass ratio for SS433, a mass for the compact object plus accretion disc of ~16 solar masses and hence the identity of the compact object as a rather massive stellar black hole.Comment: to appear in ApJ Let

Fluctuations and symmetry in the speed and direction of the jets of SS433 on different timescales

ABRIDGED We present new results on the variations in speed and direction of the jet bolides in the Galactic microquasar SS433, from high resolution spectra, taken with the ESO 3.6-m New Technology Telescope almost nightly over 0.4 of a precession cycle. We find: (i) These data exhibit multiple ejections within most 24-hour periods and, throughout the duration of the observing campaign, the weighted means of the individual bolides, in both the red jet and the blue jet, clearly exhibit the pronounced nodding known in this system. (ii) We present further evidence for a 13-day periodicity in the jet speed, and show this cannot be dominated by Doppler shifts from orbital motion. (iii) We show the phase of this peak jet speed has shifted by a quarter of a cycle in the last quarter-century. (iv) We show that the two jets ejected by SS433 are highly symmetric on timescales measured thus far. (v) We demonstrate that the anti-correlation between variations in direction and in speed is not an artifact of an assumption of symmetry. (vi) We show that a recently proposed mechanism (Begelman et al 2006) for varying the ejection speed and anti-correlating it with polar angle variations is ruled out. (vii) The speed of expansion of the plasma bolides in the jets is approximately 0.0024c. These novel data carry a clear signature of speed variations. They have a simple and natural interpretation in terms of both angular and speed fluctuations which are identical on average in the two jets. They complement archival optical data and recent radio imaging.Comment: to appear in A&A (8 pages

Life after eruption - I. Spectroscopic observations of ten nova candidates

We have started a project to investigate the connection of post-novae with the population of cataclysmic variables. Our first steps in this concern improving the sample of known post-novae and their properties. Here we present the recovery and/or confirmation of the old novae MT Cen, V812 Cen, V655 CrA, IL Nor, V2109 Oph, V909 Sgr, V2572 Sgr, and V728 Sco. Principal photometric and spectroscopic properties of these systems are discussed. We find that V909 Sgr is a probable magnetic CV, and that V728 Sco is a high-inclination system. We furthermore suggest that the two candidate novae V734 Sco and V1310 Sgr have been misclassified and instead are Mira variables.Comment: 11 pages, 7 figures (some of them in lower resolution), to be published in MNRA