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Origins of the Slow and the Ubiquitous Fast Solar Wind
Fineschi, S.; O'Neal, R.; Kohl, J. +4 more
We present in this Letter the first coordinated radio occultation measurements and ultraviolet observations of the inner corona below 5.5Rs, obtained during the Galileo solar conjunction in 1997 January, to establish the origin of the slow solar wind. Limits on the flow speed are derived from the Doppler dimming of the resonantly scatte…
Extraplanar Dust in the Edge-On Spiral NGC 891
Savage, Blair D.; Howk, J. Christopher
We present high-resolution (0.6"-0.65") optical broad-band images of the edge-on Sb galaxy NGC 891 obtained with the WIYN 3.5-m telescope. These BVR images reveal a complex network of hundreds of dust absorbing structures far from the mid-plane of the galaxy. The dust structures have a wide range of morphologies and are clearly visible to [ζ]≤1.5 …
Multiwavelength Monitoring of the BL Lacertae Object PKS 2155-304 in 1994 May. III. Probing the Inner Jet through Multiwavelength Correlations
Shull, J. M.; Takahashi, T.; Urry, C. Megan +16 more
In 1994 May, the BL Lac object PKS 2155-304 was observed continuously for ~10 days with the International Ultraviolet Explorer and the Extreme Ultraviolet Explorer and for 2 days with ASCA, as well as with ROSAT and with ground-based radio, infrared, and optical telescopes. The light curves show a well-defined X-ray flare followed by a broader, lo…
EUVE J0317-855: a rapidly rotating, high-field magnetic white dwarf
Christian, D. J.; Wickramasinghe, D. T.; Vennes, S. +2 more
Spectropolarimetric observations of the extreme-ultraviolet (EUV) source and high-field magnetic white dwarf EUVE J0317-855 (=RE J0317-853) in the wavelength range 4200-7200 A reveal a strongly structured circular polarization spectrum with a peak polarization of 8 per cent. The strongest features in the polarization spectrum are attributed to Hα …
Coordinated ultraviolet and Hα spectroscopy of bright O-type stars.
Kaper, L.; Kambe, E.; Fullerton, A. W. +7 more
As part of our search for the origin of stellar-wind variability, we have conducted simultaneous ultraviolet and Hα spectroscopy of a number of bright O stars. The observed changes in the Hα line occur at low velocity (0-0.2vinfinity_) on timescales that are characteristic of the development and evolution of discrete absorption componen…
Whisper, a Resonance Sounder and Wave Analyser: Performances and Perspectives for the Cluster Mission
Fergeau, P.; Décréau, P. M. E.; Canu, P. +7 more
The Morphology of Distant Cluster Galaxies. II. HST Observations of Four Rich Clusters at z ~= 0.4
Dressler, Alan; Oemler, Augustus, Jr.; Butcher, Harvey R.
We present Hubble Space Telescope (HST) WF/PC and WFPC2 observations of four rich clusters of galaxies at redshifts z ~ 0.4: CL 1447+2619, CL 0939+4713, CL 0024+1654, and Abell 370. Extensive ground-based observations have shown that all have substantial populations of blue, star-forming, and (in some cases) starbursting galaxies. We find the gala…
Infrared spectral energy distributions of the interacting galaxies ARP 244, NGC 6240, and ARP 220.
Schulz, B.; Klaas, U.; Heinrichsen, I. +1 more
For the luminous galaxies Arp 244, NGC 6240 and Arp 220 detailed infrared spectral energy distributions between 3 and 200µm obtained with ISOPHOT are presented. The maximum of the infrared energy distribution can now clearly be determined. The SEDs can be well represented by cold dust emission with temperatures of 30-50K which by far dominat…
A multiwavelength study of the Seyfert 1 galaxy MCG-6-30-15
Fabian, A. C.; Reynolds, C. S.; Celotti, A. +1 more
We present a multiwaveband spectroscopic study of the nearby Seyfert 1 galaxy MCG-6-30-15. New optical spectra from the Anglo-Australian Telescope are presented which clearly show the effects of dust extinction/reddening on both the emission-line spectrum and the non-stellar AGN continuum. The reddening is constrained to be in the range E(B-V)=0.6…
Hubble Space Telescope Observations of Planetary Nebulae in the Magellanic Clouds. V. Mass Dependence of Dredge-up and the Chemical History of the Large Magellanic Cloud
Ford, H. C.; Harrington, J. P.; Wood, P. R. +6 more
A photoionization analysis of Hubble Space Telescope UV and ground-based optical spectrophotometry is given for eight more planetary nebulae (PNs) in the Large Magellanic Cloud (LMC). This allows the central stars to be placed accurately on the H-R diagram and permits the determination of the He, C, N, O, Ne, S, and Ar abundances. In some cases, t…