Black holes undergoing accretion are thought to emit the bulk of their power in the X-ray band by releasing the gravitational potential energy of the infalling matter. At the same time, they are capable of producing highly collimated jets of energy and particles flowing out of the system with relativistic velocities. Here we show that the 10-solar

Inverting the stellar statistics equation from 2MASS star counts, we obtain the 3D density distribution of the Galactic bulge as well as its luminosity function in the K-band. This results in a boxy bulge with axial ratios 1:0.5:0.4 and a major axis angle with respect to the Sun-galactic center of 20°-35°.

A general study of the fermionic structure of the 331 models with eta arbitrary shows the possibility of obtaining 331 vector-like models with mirror fermions. On one hand, the existence of mirror fermions gives a possible way to fit the discrepancy in the bottom quark asymmetries from the prediction of the standard model. On the other hand, the

We report on the first pointed X-ray observations with XMM-Newton and RXTE satellites of the X-ray source RX J0757.0+6306 = HT Cam. We detect a strong 515 s X-ray modulation confirming the optical photometric period found in 1998, which definitively assigns this source to the intermediate polar class of magnetic cataclysmic variables. The lack of

We present accurate and deep multiband B,R,Hα data for the globular cluster ω Cen collected with the Advanced Camera for Surveys on HST. The photometric catalogue includes more than one million stars. By adopting severe selection criteria we identified more than 600 bona fide White Dwarfs (WDs). Empirical evidence suggests that a small sample of

Los problemas relacionados con la inhomogeneidad en densidad de las regiones HII gigantes, y sus consecuencias sobre la pérdida de los fotones Lyman, sientan el punto de partida de esta tesis. En ella, en primer lugar, realizamos un modelo estadístico para las regiones HII inhomogéneas. Posteriormente, comparamos las predicciones de los modelos con