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The Structure of Stellar Coronae in Active Binary Systems
Sanz-Forcada, J.; Dupree, A. K.; Brickhouse, N. S.
A survey of 28 stars (22 active binary systems, plus six single stars or wide binaries for comparison) using extreme ultraviolet spectra has been conducted to establish the structure of stellar coronae in active binary systems from the emission measure distribution (EMD), electron densities, and scale sizes. Observations obtained by the Extreme Ul…
Chandra Observations of QSO 2237+0305
Agol, E.; Garmire, G. P.; Bautz, M. W. +2 more
We present the observations of the gravitationally lensed system QSO 2237+0305 (Einstein Cross) performed with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory on 2000 September 6 and on 2001 December 8 for 30.3 and 9.5 ks, respectively. Imaging analysis resolves the four X-ray images of the Einstein Cross. A possible f…
The Baldwin Effect and Black Hole Accretion: A Spectral Principal Component Analysis of a Complete Quasar Sample
Laor, Ari; Wills, D.; Shang, Zhaohui +4 more
We have performed a spectral principal component analysis (SPCA) for an essentially complete sample of 22 low-redshift QSOs with spectral data from Lyα to Hα. SPCA yields a set of independent principal component spectra, each of which represents a set of relationships among QSO continuum and line properties. We find three significant principal com…
Rotation and magnetic field in the Be star omega Orionis
Frémat, Y.; Zorec, J.; Neiner, C. +5 more
Stellar populations and star cluster formation in interacting galaxies with the Advanced Camera for Surveys
de Grijs, Richard; Lee, Jessica T.; Clemencia Mora Herrera, M. +2 more
Pixel-by-pixel colour-magnitude and colour-colour diagrams—based on a subset of the Hubble Space Telescope Advanced Camera for Surveys Early Release Observations—provide a powerful technique to explore and deduce the star and star cluster formation histories of the Mice and the Tadpole interacting galaxies. In each interacting system we find some …
Shaping Proto-Planetary and Young Planetary Nebulae with Collimated Fast Winds
Lee, Chin-Fei; Sahai, Raghvendra
Using two-dimensional hydrodynamical simulations, we investigate the interaction of a collimated fast wind (CFW) interacting with a spherical asymptotic giant branch (AGB) wind as the mechanism for shaping proto-planetary nebulae (PPNs) and young planetary nebulae. In particular, we compare our simulations with the observations of an evolved PPN w…
Star cluster formation and evolution in nearby starburst galaxies - I. Systematic uncertainties
Bastian, N.; Gallagher, J. S.; de Grijs, R. +4 more
The large majority of extragalactic star cluster studies performed to date have essentially used two- or three-passband aperture photometry, combined with theoretical stellar population synthesis models, to obtain age, mass and extinction estimates, and sometimes also metallicities. The accuracy to which this can be performed depends on the choice…
Hubble Space Telescope WFPC2 Imaging of the Disk and Jet of HV Tauri C
Ménard, François; Krist, John E.; Brandner, Wolfgang +4 more
We have obtained Hubble Space Telescope (HST) WFPC2 images of the HV Tauri young triple system. The tertiary star appears as a compact bipolar nebula at visual wavelengths as already known in the near-infrared. New, deeper adaptive optics observations made at the Canada-France-Hawaii Telescope show no point source in the nebula to a limiting magni…
Implications of the observed anticorrelation between solar wind speed and coronal electron temperature
Gloeckler, George; Geiss, Johannes; Zurbuchen, Thomas H.
Electron temperatures at the source of the solar wind are now obtained routinely and continuously from measurements of charge states of solar wind ions with modern solar wind composition spectrometers over a wide range of solar wind speeds. While the general anticorrelation between solar wind speed and electron temperature was previously noted, th…
Guilt by Association: The 13 Micron Dust Emission Feature and Its Correlation to Other Gas and Dust Features
Sloan, G. C.; Kraemer, Kathleen E.; Price, Stephan D. +1 more
A study of all full-scan spectra of optically thin oxygen-rich circumstellar dust shells in the database produced by the Short Wavelength Spectrometer on ISO reveals that the strength of several infrared spectral features correlates with the strength of the 13 µm dust feature. These correlated features include dust features at 19.8 and 28.1 …