An observational test of the binary hypothesis for the origin of the blue straggler (BS) stars has been performed searching for radial velocity variables among 27 BS in five galactic clusters. The significance of the BS phenomenon for the interpretation of evolutionary synthesis models and the spectra of elliptical galaxies is briefly discussed.

Given observed equivalent widths of Mg II and Mg I absorptions due to an interstellar cloud in which a late-B star is embedded, it is shown that the basic physical parameters (kinetic temperature, mean density, electron density, and radius) can be constrained. Hydrogen ionization by means of cosmic rays and the effect of the stellar radiation field

Results are presented for the sun's radial velocity in integrated sunlight. A resonant scattering spectrometer has been used to determine the frequencies and amplitudes of p-modes with spherical harmonics of degree (l) of less than 3, and a second spectrophotometer, which observes part of the sun by means of a spatial filter, has been used to

A CCD imaging survey of elliptical galaxies which present radio jets is described. The photometric and morphological properties of these galaxies and their nearby companions are described by Fourier analysis of the intensity variations along a set of elliptical contours fitted to the intensity distribution. A large fraction of the sample shows

The dynamics of mergers between two unequal elliptical systems was studied with self-consistent numerical simulations. Comparisons of these models to real ellipticals are made in a variety of properties, which include the mean central surface brightness, the shape of the surface brightness profile, and the type of rotation curve and dispersion

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