The intensity distribution of the penumbra at different stages of evolution has been analyzed. The results have been different for both evolved and primitive penumbras. While the former present almost symmetrical, single-peaked histograms, the same does not occur for the latter, their distributions being, preferentially, asymmetrical or double

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The authors analyze a set of optically faint emission-line galaxies discovered as strong Hα emitters in an objective prism survey (Wamsteker et al, 1985). This selection method is suitable for the detection of very low excitation galaxies in a dusty medium. The optical and infrared properties of this sample resemble those of IR luminous galaxies

Using a resonant scattering spectrophotometer the authors measured the radial velocity of the Sun at the K I 769.9 nm line with very high resolution and temporal stability. The observations carried out at Izaña (Tenerife) continuously for the last three years, have been used to search for solar g modes. Individual peaks, well above noise level, are

Despite theoretical predictions on the existence of solar gravity oscillations (g modes), their detection is still marginal. The main reasons are their frequencies, nu less than 0.2 mHz, and amplitudes of less than 10 cm/s. However, because these modes are extremely sensitive to the physical conditions in the very deep sun, they can give detailed