The way in which the effect of the instrumental polarization of a spectrograph can distort the shape of the intensity profiles in sunspots is shown empirically. A spectral region around a magnetically sensitive line and a sunspot away from the disk center were chosen. The resulting limitations which arise when trying to derive physically meaningful

In the present comparative study of published values for the scale lengths of spiral galaxies' exponential disks, the average value of the discrepancy for more than 120 galaxies is 23 percent, with a standard deviation of 20 percent. Neither systematic trends nor correlations of discrepancies with such galaxy parameters as morphological type, arm

Observations of the Jupiter were carried out using a refined version of the stellar seismometer with a sensitivity of better than 50 cm/s. The observations revealed the existence of strong velocity variations of the planets in the 10-20-min period range. It is concluded that the observed variations can only be explained as global acoustic modes

The way in which the evaluation of any moment of the mass distribution, as given by the Zeldovich (1970) approximation, may be reduced to the computation of an integral is shown. A method for obtaining a two-point correlation function from the product of the density fluctuation and the Lagrangian coordinate is presented. Local approximations that

It is argued that internal gravity waves generated by the convective envelope of a star may be effective in producing a weak mixing in its radiative interior. The spectrum of wavelengths and frequencies generated is estimated. Only the largest horizontal wavelengths and the lowest frequencies contribute significantly to the wave energy flux and the

High-speed photometric observations of the recently discovered roAp star 10 Aql were performed in the J(1.22-micrometer) filter. A total of 47.2 hours of data were obtained during seven consecutive nights in July 1990, using a standard infrared photometer attached to the Cassegrain focus of the 1.54 m Carlos Sanchez telescope at the Observatorio