We report on UV and X-ray spectroscopy and broadband optical observations of the ultraluminous X-ray source in Holmberg II. Fitting various stellar spectral models to the combined, non-simultaneous data set, we find that normal metallicity stellar spectra are ruled out by the data, while low-metallicity, Z = 0.1 Z &sun;, late O-star spectra provide

Here we present our determination of the black hole - mass function for spiral galaxies in our local universe. We have established our black hole - mass function from a volume-limited sample, consisting of a statistically complete collection of the brightest spiral galaxies in the Southern (δ 0°) hemisphere. The volume-limited sample is defined by

The Ly α lines of H I and He II are two of the spectral lines of choice for FUV and EUV channels of narrowband imagers on board sounding rockets and space telescopes, which provide spectacular intensity images of the outer solar atmosphere. Since the magnetic field information is encoded in the polarization of the spectral line radiation, it is

Our long-term photometric monitoring of southern nova-like cataclysmic variables with the 1.3-m Small and Moderate Aperture Research Telescope System (SMARTS) telescope found BB Doradus fading from V˜ 14.3 towards a deep low state at V˜ 19.3 in 2008 April. Here we present time-resolved optical spectroscopy of BB Dor in this faint state in 2009. The

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We have developed a comprehensive, multi-threaded, three-dimensional model of the plasma dynamics and energetics of a prominence and its overlying arcade (Luna et al. 2012). In this model, the basic magnetic structure is that of two interacting sheared arcades, while the cool condensations comprising the prominence are formed by the well-studied