We discuss the mechanism for the oscillatory behavior of the static interparticle potential in a degenerate electron plasma. This behavior, observed in metallic alloys, is commonly referred to as 'Friedel oscillations', and its origin associated to the Kohn singularity. We show that, although this interpretation is adequate for large distances, the

The IRIS network has accumulated full disk helioseismological data since July 1989, i.e. a complete 11-year solar cycle. Since the last paper publishing a frequency list [A&A 317 (1997) L71], not only has the network acquired new data, but has also developed new co-operative programs with compatible instruments [Abstr. SOHO 6/GONG 98 Workshop (1998

After a brief description of how spectral emission lines can be studied by the self-absorption-curve method, we show what happens when it is used to examine the FeIII and NII lines of P Cygni. An extremely surprising result is obtained; more highly-excited pure-emission lines without blueshifted absorption appear to be optically thicker than less

IAUC 7617 available at Central Bureau for Astronomical Telegrams.

Not Available

Time-distance analysis is emerging as a powerful diagnostic tool in local helioseismology. By directly measuring propagation times of wave packets between selected locations at the surface of the sun, and their variations over specific areas, a directed diagnostic of the physical properties of the region below these areas can be achieved. We