We have used the Chandra X-ray Observatory to observe the following six black hole X-ray transients in quiescence: GRO J0422+32 (orbital period Porb=5.1 hr), A0620--00 (Porb=7.8 hr), GS2000+25 (Porb=8.3 hr), 4U1543--47 (Porb=27.0 hr), GRO J1655--40 (Porb=62.9 hr), GS2023+338 (Porb=155 hr). Previous to these Chandra observations there was only a

We present the kinematical analysis of HI and HII gases within the disk of NGC 3359. There is a strong trend of non-circular gas flow as seen in the velocity field maps of both media. Specifically, the regions near the bar are marked by very skewed isovelocity contour lines. Within the area, velocity differences between the neutral atomic and

This paper presents a detailed description, analysis, and interpretation of the spectropolarimetric observations recently reported by Socas-Navarro, Trujillo Bueno, & Ruiz Cobo. These observations consist of time series of Stokes I and V profiles above a sunspot umbra. The spectral lines observed simultaneously are the Ca II chromospheric lines at

The importance of the study of Planetary Nebulae (PNe) in our Galaxy and in external galaxies is outlined, with the aim of highlighting how the combined study of galactic and extragalactic PNe can bring a substantial contribution to our understanding of the late stages of stellar evolution and of related astrophysical topics. We then illustrate the

We present improved visual and near-infrared empirical mass-luminosity relations for very low mass stars (M

We have obtained adaptive optics images and accurate radial velocities for 7 very low mass objects, In the course of a long term effort to determine accurate masses for very low mass stars (M