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Abstract:

Thanks to a stellar evolution code able to compute through the C-flash we link the binary population synthesis of single degenerate progenitors of type Ia supernovae (SNe Ia) to their physical condition at the time of ignition. We show that there is a large range of possible ignition densities and we detail how their probability distribution depends on the accretion properties. The low density peak of this distribution qualitatively reminds of the clustering of the luminosities of Branch-normal SNe Ia. We tighten the possible range of initial physical conditions for explosion models: they form a one-parameter family, independent of the metallicity. We discuss how these results may be modified if we were to relax our hypothesis of a permanent Hachisu wind or if we were to include electron captures.

Abstract:

At least 10% of all massive stars are expected to merge with a binary companion during their evolution, producing an initially rapidly rotating merged object. These merger products are excellent candidates for B[e] supergiants. In this review we summarize the different types of mergers and show that the merger rate is compatible with the B[e] supergiant formation rate. We then apply the merger paradigm to various observed systems that have been suspected or proposed to be merged systems: the progenitor of SN 1987A, Sheridan 25, the B[e] supergiant RA and eta Carinae.

Abstract:

We investigate the UV upturn phenomenon of elliptical galaxies by applying the binary model of hot subdwarfs of Han et al. (2002, 2003). Preliminary results show that the model provides a natural explanation for the UV upturn phenomenon and that the model could be used to detect low level recent star formation.

Abstract:

We present near-infrared imaging of a sample of the faint, hard X-ray sources discovered in the 2001 Chandra Advanced CCD Imaging Spectrometer (ACIS)-I survey towards the Galactic Centre (GC) by Wang et al. These ∼800 discrete sources represent an important and previously undetected population within the Galaxy. From our Very Large Telescope observations of 77 X-ray sources, we identify candidate K-band counterparts to 75 per cent of the Chandra sources in our sample. The near-infrared magnitudes and colours of the majority of candidate counterparts are consistent with highly reddened stars, indicating that most of the Chandra sources are likely to be accreting binaries at or near the GC. © 2005 RAS.