As part of the Chandra Guaranteed Time Program we are imaging M31 once/month. The HRC is used to observe the entire galaxy to 10**37 ergs/sec, and interesting transients are followup up with ACIS observations which reach 10**36 ergs/sec. Thus the known (Galactic) types of accretion powered x-ray transients can detected and their spectra can be

File table1.dat contains the identification number, the coordinates (2000), the Hα+[NII] flux and the [OIII]5007 flux of the PNe detected in Messier 33, with the Isaac Newton Telescope (INT) (La Palma, Spain) in 1998, November. File table2.dat contains the identification number, the coordinates (2000), the Hα flux, the [OIII]5007 flux and the

This article presents an introduction to optical pumping, atomic polarization and the Hanle effect in weakly magnetized stellar atmospheres. Although the physical processes and the theoretical framework described here are of interest for applications in a variety of astrophysical contexts (e.g. scattering polarization in circumstellar envelopes and

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Four years of GOLF velocity time series have been used to study the low frequency part of the solar spectrum below 1.5 mHz. This paper discusses the methods already developed for the research of the low-degree low-order acoustic modes by Garcia et al. (2000) and for the gravity modes by Turck-Chieze et al. (2000). These methods are based on our

Nuestro objetivo es mejorar los analisis espectroscopicos para intentar obtener la descripcion mas realista posible de las atmosferas de las estrellas OB de la Galaxia. De esta manera podremos responder a ciertas preguntas que esten abiertas hoy en dia sobre estos objetos, en especial a si la discrepancia de He se puede explicar via procesos de