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We present X-ray observations of the close binary nucleus of the planetary nebula SBS 1150+599A obtained with the XMM-Newton satellite. Only one component of the binary can be observed in optical-UV. New X-ray observations show that the previously invisible component is a very hot compact star. This finding allows us to deduce rough values for the basic parameters of the binary. With a high probability the total mass of the system exceeds Chandrasekhar limit and makes the SBS 1150+599A one of the best candidate for a supernova type Ia progenitor. [ABSTRACT FROM AUTHOR]

We have observed WZ Sge with high resolution echelle spectroscopy during the 2001 superoutburst. The hot-spot arising near the secondary star is again visible 15 days after its first detection. We have been able to measure its position as a function of orbital phase directly from individual spectra. We derive a a semiamplitude of K[sub hs] = 457 ± 16kms[sup -1] and a systemic velocity of γ = 0 ± 14km s[sup -1]. We also show that the accretion disc has an ellipsoidal shape with a value around e = 0.75. Based on these facts we derive a phase shift of Δφ = -0.12 between the eclipse and the inferior conjuntion ephemeris. If this is the case, then the hot-spot appears located at the trailing side of the red dwarf and must be the result of in-falling material back to the donor star. [ABSTRACT FROM AUTHOR]

The article discusses the results of the survey on the expansion velocities of planetary nebula. For the brightness of the stars, asymmetries in the line profile are clear. The mean expansion velocities are remarkably uniform despite the diversity in planetary nebula progenitors in different galaxies.