We present non-LTE analyses of four M33 early B supergiant stars and five Galactic counterparts. This is the first time that B supergiants beyond the Magellanic Clouds are analyzed by means of detailed non-LTE techniques. Among the M33 stars, new spectroscopic observations of B38 (ob21-108) are presented and the object is classified as B1 Ia. The

We contribute to the subject of the physical interpretation of exact solutions by characterizing them through a systematic study in terms of unambiguous physical concepts coming from systems in linearized gravity. We use the physical meaning of the leading order behavior of the Weyl spinor components $Psi_0^0$, $Psi_1^0$ and $Psi_2^0$ and of the

We have been regularly observing the bulge and inner disk of M31 for nearly one year, using both the HRC-I and ACIS-I instruments on the Chandra X-Ray Observatory. We present results from our program that are of interest to the study of the ISM in M31. In particular, we find that the unresolved emission within 3' of the center of M31 has a

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