We present a direct determination of the mass of the system components in the soft X-ray transient A0620 -00. Infrared photometry during 1990 allows us to determine the double-humped quiescent light curve, which we then fit with an ellipsoidal model. We obtain solutions in the mass-ratio-inclination plane which, when combined with the rotational

I discuss in this paper the more likely physical mechanisms that could provide the energy input for the supersonic motions observed in giant extragalactic HII regions, together with preliminary results of an ongoing observational program that aims to study, with high spatial and spectral resolution, the kinematics of the ionized gas of the regions.

The kinematics of Planetary Nebulae are analyzed in terms of the solutions to the equations of hydrodynamic equilibrium developed by J. Canto. We apply our analysis to the Planetary Nebulae NGC 6905 and NGC 6537. A detailed spectroscopic study of these objects reveals the existence of high nuclear velocities, together with complex kinematic

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The solar p-mode spectrum of very low l is measured with high accuracy for a long enough period of time so as to allow the search for solar cycle variations. In this paper solar cycle variations of the frequency and energy of the modes are confirmed. Moreover, a slight variation, within errors, of its rotational splitting with the solar cycle, is

The evolutionary scenario concerning the production and the cooling of He white dwarfs is revisited and discussed. We show that, for a given star metallicity, the minimum mass of H-rich envelopes able to support a red giant structure linearly decreases when the logarithm of the red giant luminosity increases. Increasing the metallicity the mass of