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

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Oxygen abundances for a large sample of dwarf stars in the Galactic thin and thick disks are determined from a non-LTE analysis of the oxygen triplet lines at 777 nm. Kinematic criteria are employed to determine whether a star belongs to the thin or thick disk. Temperatures are obtained from photometric calibrations based on the infrared flux

We present the first optical polarimetric observations of the runaway microquasar LS 5039. Our results reveal the presence of a large amount (˜5%) of polarized emission towards this binary system. By combining polarimetric and spectroscopic observations of some stars in the field together with available statistical information on the galactic

We present an RI photometric survey covering an area of 430 arcmin2 around the multiple star sigma Orionis. The observations were conducted with the 0.8 m IAC-80 Telescope at the Teide Observatory. The survey limiting R and I magnitudes are 22.5 and 21, and completeness magnitudes 21 and 20, respectively. We have selected 53 candidates from the I

Here we report on the properties of the star forming factory, in which the continuous creation of stars results into a highly concentrated, massive (globular cluster-like) stellar system. We show that under very general conditions a large-scale gravitational instability in the ISM, that triggers the collapse of a massive cloud, leads with the aid