Results are presented on a non-LTE analysis of high-resolution Cassegrain echelle CCD spectra of the four most luminous stars in the NGC 346 cluster in the SMC, obtained with the ESO 3.6-m telescope, making it possible to estimate the age of the NGC 346 cluster and to trace its evolution. The results yield the effective temperatures, gravities

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The observed cooling rate of hot gas in clusters is much lower than that inferred from the gas density profiles. This suggests that the gas is being heated by some source. We use an adaptive-mesh refinement code (FLASH) to simulate the effect of multiple, randomly positioned, injections of thermal energy within 50 kpc of the centre of an initially

The QUEST (QUasar Equatorial Survey Team) Phase 1 camera has collected multibandpass photometry on a large strip of high Galactic latitude sky over a period of 26 months. This robust data set has been reduced and nightly catalogs compared to determine the photometric variability of the ensemble objects. Subsequent spectroscopic observations have

We report the result of a new Chandra observation of the black hole X-ray transient H 1705-250 in quiescence. H 1705-250 was barely detected in the new ˜50 ks Chandra observation. With five detected counts, we estimate the source quiescent luminosity to be LX ˜ 9.1 × 1030 erg s-1 in the 0.5-10 keV band (adopting a distance of 8.6 kpc). This value