New pulsation modes in two delta Scuti stars of Praesepe cluster, BQ and BW Cnc, have been detected during the STEPHI VI campaign in 1995. In particular, 3 frequencies for BQ Cnc and 9 frequencies for BW Cnc have been found above a 99% confidence level. The possibility of the presence of a g-mode present in BQ Cnc is discussed, considering its

We present results of analysis of observations of the X-ray source 2A 1704+241 with the Rosat Position Sensitive Proportional Counter (PSPC) and the High Resolution Imager (HRI). 2A 1704+241 was first associated with the M3II star HD154791 (Garcia et al. 1983). The identification, based upon observation with the HEAO 1 SMC and the Einstein IPC, was

The two main perturbative schemes for the non-linear evolution of large-scale structures are the Lagrangian and the Eulerian ones. The former has been set as a much more powerful technique, due to its property of yielding the exact solution in the plane-symmetric case. We have applied the Eulerian scheme to this plane symmetric case and have

We present the results of optical photometry of the X-ray transient XTE J2123-058. CCD R-band images, have been obtained since 2 Jul until 29 Sep 1998. Following the behaviour of the XTE/ASM lightcurve, the system decline optically from the begining of August at approximately 0.1 mag/day. Despite the drop in luminosity, we observe a dramatic

A sample of 47 faint Gigahertz Peaked Spectrum (GPS) radio sources selected from the Westerbork Northern Sky Survey (WENSS) has been imaged in the optical and near-infrared, resulting in an identification fraction of 87 per cent. The R-IR-K colours of the faint optical counterparts are as expected for passively evolving elliptical galaxies

We have studied analytically the mean pull on shells of real (anisotropic and/or non-isolated) mass concentrations. Using a non-linear scheme, the radial component of the peculiar velocity is averaged over solid angle (V_0) and mass-averaged (V^*_0) for several different generic configurations. Nine Local Supercluster(LS)-like objects and six Great