The K I 7699-A resonance absorption line was used to observe a group of 18 early-type stars within a 200-pc radius of the sun with a signal-to-noise ratio of 50-250. The interstellar absorptions provide a way to 'tag' a cloud via its radial velocity to within +/-1.5 km/s. Based on the hypothesis of pressure confinement, the temperatures of the

IAUC 5578 available at Central Bureau for Astronomical Telegrams. IAUC 5578 available at Central Bureau for Astronomical Telegrams.

A description of the stray-light problem based on a radiative transfer approach is presented. The 2D convolution that describes the effect of the stray-light is recovered in this formalism. The controversy raised by the old normalization condition is satisfactorily eliminated within the present description. The present formalism is applied to

We present the results of a five-month spectroscopic monitoring campaign of two radio loud quasars, PKS 1217 + 023 and PKS 1302 - 102. There is a pronounced lack of variability in 1302 - 102 apart from a possible small change in the continuum level near the end of the monitoring period, but 1217 + 023 underwent a 20 percent continuum decrease in

We have used high-resolution spectra of the Ca II H resonance line in late-type dwarfs, obtained with high S:N ratios, over a period of four years to widen our understanding of the dynamical behavior of the Ca II emission cores. All of the stars dealt with in this article, which are chromospherically active, show variability both in core emission

EN EL PRESENTE TRABAJO, SE PONE DE RELIEVE LA NECESIDAD DE REVISAR CONCEPTON QUE USUALMENTE SE EMPLEAN EN LA INTERPRETACION DEL ESPECTRO SOLAR. EN PARTICULAR, SE MUESTRA QUE LA PROFUNDIDA MEDIA DE FORMACION DE UNA LINEZ ESPECTRAL, FRECUENTEMENTE EMPLEADA COMO ELEMENTO DE DIAGNOSTICO, NO TINE ESPECIAL INTERES PARA LA ASIGNACION DE UNA MEDIDA DADA A