Measurements of optical emission-line flux variations based on spectra of the Seyfert galaxy NGC 5548 obtained between December 1988 and October 1989 are reported. All of the measured optical emission lines, H-alpha, H-beta, H-gamma, He I 5876, and He II 4686, exhibit the same qualitative behavior as the UV and optical continua, but with short time

We derive effective temperatures, luminosities and related parameters for a sample of eight Wolf-Rayet stars - seven WN stars and a WO star - by computing elaborate photoionization models of their surrounding ring nebulae. The most recent non-LTE WR model atmospheres are used for the input stellar ionizing flux distributions. The photoionization

ACTUALMENTE, LA INFORMACION HELIOSISMOLOGICA QUE PUEDE OBTENERSE A PARTIR DE ESTACIONES UNICAS SOBRE LA SUPERFICIE TERRESTRE SE ENCUENTRA ANALIZADA HASTA EL LIMITE. LA COMUNIDAD CIENTIFICA ESTA CONVENCIDA DE QUE, PARA PROSEGUIR EL AVANCE EN ESTE CAMPO, ES NECESARIO DISPONER DE SERIES TEMPRALES LARGAS E ININTERRUMPIDAS DE OBSERVACIONES DE LAS

Not Available (1 data file).

Lithium abundances, or upper limits, have been derived for 161 galactic carbon stars, selected from the Two Micron Sky Survey, using high resolution, high signal to noise ratio spectra and synthetic spectrum fitting. Fourteen of these C-stars present surface lithium abundances [log ɛ(Li) ≥ 1.0] higher than theoretically expected during the AGB

Connecting observational data to recent theoretical prescriptions for the luminosity of RR Lyrae, we present a new estimate of the bolometric magnitude of the first brightest red giant for a selected sample of galactic globular clusters. Comparison with theoretical prescriptions for the red giant luminosity at the He-flash discloses an excellent