A ring-diagram analysis technique has been applied to a region of the Sun of about 15 deg^2 area close to the disk center at dates chosen for several solar rotations in 1996: April 5, May 1, May 28, June 27, July 23, August 20, August 21, and September 18. The horizontal velocity flows inferred directly beneath the solar surface have thus been

We estimate the typical spectrum of spatial fluctuations of intensity due to the penumbral filaments. High angular resolution continuum images are used (cut-off frequencies equivalent to 0.28" wavelength of about 5257 Å). The amplitude of the observed spectra follows the modulation transfer function of our optical system. In other words, the

We report the detection of the slow-moving wind into which the compact supernova remnant SN 1997ab is expanding. Echelle spectroscopy provides clear evidence for a well-resolved narrow (full width at zero intensity, FWZI ~180 km s^-1) P Cygni profile, both in Hα and Hβ, superimposed on the broad emission lines of this compact supernova remnant

An analysis based on a comparison between observations and stellar models has been carried out to identify radial modes of oscillations in several multi-periodic delta Scuti stars of the Praesepe cluster (BU, BN, BW and BS Cnc). The assumption that all the stars considered have common parameters, such as metallicity, distance or age, is imposed as

Not Available

We discuss observations and seismic analyses for three multi-periodic delta Scuti stars in the Praesepe cluster: BU, BN and BV Cnc. For two stars (BU and BN Cnc) we re-analyse published photoelectric photometry and show that using statistical weights results in a dramatic reduction in the noise level. We detect seven frequencies in BU Cnc and eight