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The Extraordinary Cataclysmic Binary RU Pegasi: The Hottest White Dwarf in a Dwarf Nova?
Sion, Edward M.; Urban, Joel
We present the results of the first multicomponent synthetic spectral analysis of International Ultraviolet Explorer (IUE) archival spectra of the long-period dwarf nova RU Peg during quiescence. The best-fit, high-gravity, solar composition photosphere models yield Teff=50,000-53,000 K with scale factor distances of 250 pc. Optically t…
Evolution of a semicircular flux rope with two ends anchored in the photosphere
van Ballegooijen, A. A.; Lin, J.; Forbes, T. G.
We investigated a coronal magnetic configuration including a semicircular flux rope with two ends anchored in the photosphere. The background field is produced by two source regions on the photosphere. We study the evolution of this configuration in response to the gradual change in the background field, which is modeled by varying either the stre…
The dynamics of an erupting prominence
Klein, K. -L.; Mouradian, Z.
Hα full disk observations and radio interferometry at decimetre and metre wavelengths are used to probe the dynamics of ejecta and electron acceleration during a solar eruptive event on 1990 September 14. An erupting prominence and a moving type IV radio source are shown to trace a common magnetic structure during its rise from ~ 10 Mm to 3 R…
A wavelet analysis of quasi-periodic variability across a solar coronal hole region
Bromage, B. J. I.; Marsh, M. S.; Walsh, R. W.
High time resolution (~13 s cadence) Solar and Heliospheric Observatory (SOHO) Coronal Diagnostic Spectrometer (CDS) Grazing Incidence Spectrometer (GIS) time series data is analysed for evidence of quasi-periodic variability in the solar corona. The observations are obtained from a GIS study of a coronal hole boundary region taken in October 1997…
First XMM-Newton observations of strongly magnetic cataclysmic variables - II. Timing studies of DP Leo and WW Hor
Cropper, Mark; Ramsay, Gavin; Much, Rudi +5 more
XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables, DP Leo and WW Hor, continuously for three orbital cycles each. Both systems were in an intermediate state of accretion. For WW Hor we also obtained optical light curves with the XMM-Newton Optical Monitor and from ground-based observations. Our analysis of the X-ray and …
Far-infrared spectroscopy across the asymmetric bipolar outflows from Cepheus A and L 1448
Smith, M. D.; Eislöffel, J.; Froebrich, D.
Bipolar outflows are driven from protostars within molecular cores. They drive into molecular clouds, generating shock waves whose molecular emission lines have been observed in the infrared with ISO. We present spectroscopic data for seven locations within two asymmetric outflows,
Saturn's Rings: pre-Cassini Status and Mission Goals
Nicholson, P. D.; Spilker, L. J.; Porco, C. C. +8 more
Theoretical and observational progress in studies of Saturn's ring system since the mid-1980s is reviewed, focussing on advances in configuration and dynamics, composition and size distribution, dust and meteoroids, interactions of the rings with the planet and the magnetosphere, and relationships between the rings and various satellites. The Cass…
LOTIS, Super-LOTIS, Sloan Digital Sky Survey, and Tautenburg Observations of GRB 010921
Cline, T.; Hurley, K.; Brinkmann, J. +36 more
We present multi-instrument optical observations of the High Energy Transient Explorer (HETE-2) and Interplanetary Network error box of GRB 010921. This event was the first gamma-ray burst (GRB) partly localized by HETE-2 that has resulted in the detection of an optical afterglow. In this Letter, we report the earliest known observations of the GR…
The Helium Focusing Cone of the Local Interstellar Medium Close to the Sun
Romoli, M.; Raymond, J. C.; Bertaux, J. L. +13 more
The Solar and Heliospheric Observatory (SOHO) Ultraviolet Coronagraph Spectrometer is used to observe the interplanetary He focusing cone within 1 AU. Taken over 2 yr and from differing orbit positions, the series of observations includes measurements of He I 584 Å and Lyβ intensities. The cone itself is spatially well defined, and the He I intens…
On Formation of the Sigmoidal Structure in Solar Active Region NOAA 8100
Liu, Y.; Hoeksema, J. T.; Scherrer, P. H. +3 more
Using soft X-ray images taken by the Soft X-ray Telescope on board Yohkoh, line-of-sight magnetograms taken by SOHO/MDI and vector magnetograms taken at Beijing Astronomical Observatory, we have studied the formation of the sigmoidal structure in active region NOAA 8100 on 3-4 November 1997. The sigmoidal structure appeared after the occurrences o…