The amplitude of the gravitational waves emitted by a binary system of arbitrary eccentricity and orientation is developed in Fourier-Bessel series. Periastron advance is also considered. We discuss the influence of the orbital parameters in the spectrum of the wave amplitude. The dominant harmonic in the spectra gives a good estimation of the

Simultaneous UV and X-ray observations of the blazar PKS 0521-365 are combined with radio, IR, optical and gamma-ray data taken at different epochs to study the overall emission from 109 to 1023 Hz. The energy distribution declines from the IR to the UV range (alpha sub(opt-UV)=1.4 +/- 0.1), but hardens at higher frequencies. The remarkably flat X

We present a spectroscopic analysis of the O9.7 Iab star HDE 226868, which is the optical counterpart of Cygnus X-1. We use this extreme supergiant to test the differences in the stellar parameters derived using plane parallel hydrostatic model atmospheres and spherical non-hydrostatic models ("Unified Model"). We find that the difference is

Intermediate-resolution optical spectra of the X-ray transient J0422+32, obtained during the 1993 December mini-outburst, show a strong modulation in radial velocities and equivalent widths of all the emission lines, with a period of 0.2127+/-0.0013d (5.1h). This modulation is in good agreement with the photometric period of 0.2121d reported during

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We first discovered the presence of a particularly massive cloud in the neighborhood of the Sun, close to the Galactic plane in the direction of Perseus, toward l = 150 deg, b = -10 deg, using interstellar absorption by the 7699 A resonance line of K I (Trapero et al. 1992). In the present investigation we show the results of mapping the cloud in