Search Publications
HST Imaging Polarimetry of the Seyfert 2 Galaxy NGC 5728
Boksenberg, A.; Capetti, A.; Sparks, W. B. +2 more
We present the results of HST imaging polarimetry of NGC 5728 taken with the COSTAR corrected Faint Object Camera in the ultraviolet (3000- 3700 A) and covering the region interior to its well-known nuclear ring. The total intensity image is dominated by a bright extended core, 1" x 0.7" in size, which is resolved into a large number of compact kn…
Multi-colour photometric and spectroscopic monitoring of the WN5 star EZ Canis Majoris.
van der Hucht, K. A.; van Genderen, A. M.; Duijsens, M. F. J. +3 more
We present and analyse photometric and spectroscopic observations of the WN5 star EZ Canis Majoris obtained over a period of 7years. We discuss the changing light curve, the shift in phase of the maxima and point to flare type variability seen in one night. Small amplitude variations are reported in another night. We have investigated the change o…
ULYSSES out-of-ecliptic observations of interplanetary shocks.
Balogh, A.; Forsyth, R. J.; Burton, M. E. +4 more
Interplanetary shocks observed at the Ulysses spacecraft as it traveled from the ecliptic plane to the southern solar pole have been identified and analyzed using both magnetic field and plasma measurements. The latitude dependences of various parameters associated with the shocks (beta, θ_BN_ and Mach number) have been investigated. The direction…
Relations between the Optical Fe II Emission and Ultraviolet Spectra in Active Galactic Nuclei
Wang, Ting-Gui; Zhou, You-Yuan; Gao, An-Song
Optical Fe II emission is a general characteristic of most active galactic nuclei, but the physical conditions in the Fe II-emitting region are not yet understood. The current photoionization models underpredict the total Fe II intensity as well as optical Fe II/Hβ ratio. In this paper, we report the results of a statistical analysis of the relati…
GHRS Observations of the LISM
Linsky, Jeffrey L.
The GHRS has obtained high-resolution spectra of interstellar gas toward 19 nearby stars. These excellent data show that the Sun is located inside the Local Interstellar Cloud (LIC) with other warm clouds nearby. I will summarize the physical properties of these clouds and the three-dimensional structure of this warm interstellar gas. There is now…
Stellar chemical abundances with the GHRS.
Leckrone, D. S.; Wahlgren, G. M.; Johansson, S. +2 more
The accurate quantitative analysis of high resolution ultraviolet spectra of ultra-sharp-lined, early-type, chemically peculiar stars, obtained with the Goddard High Resolution Spectrograph on the Hubble Space Telescope, has been made possible by the synergism between state-of-the-art astrophysics and state-of-the-art atomic spectroscopy. The auth…
The central stars of the planetary nebulae NGC 7027 and NGC 6543.
Waters, L. B. F. M.; Pottasch, S. R.; Beintema, D. A. +6 more
Infrared spectra of NGC 7027 and NGC 6543 ranging from 2.4 to 45µm were obtained with the Short Wavelength Spectrometer on board the Infrared Space Observatory. A first analysis of these spectra, with the aid of photo-ionization models, is presented. We report the first detection of the [ArVI] 4.53µm and [NeVI] 7.65µm lines in th…
Charon/Pluto Mass Ratio Obtained with HST CCD Observations in 1991 and 1993
Null, G. W.; Owen, W. M., Jr.
We have analyzed Hubble Space Telescope Wide Field Camera observations of Pluto, Charon, and a reference star, acquired in 1991 and 1993, to observe Pluto's barycentric motion and determine the Charon/Pluto mass ratio, 0.124±0.008. Solution values for Charon orbital elements include the semimajor axis, 19662±81 km inclination, 96.57±0.24 deg; ecce…
HD 133656: a new high-latitude supergiant.
Trams, N. R.; Van Winckel, H.; Oudmaijer, R. D.
In the course of our study of post-Asymptotic Giant Branch objects, we discovered that the seventh magnitude A supergiant HD 133656 has an infrared excess emission due to cool circumstellar dust, and that its photospheric abundance pattern is population II like. We present a detailed abundance study of the object, and discuss its nature in terms o…
Pulsations and Line Profile Changes in the Ultraviolet Spectrum of Hercules X-1: Results from a Multiwavelength Campaign
Nagase, Fumiaki; Vrtilek, S. D.; McCray, Richard +2 more
We report simultaneous X-ray and ultraviolet observations of the X-ray binary pulsar Hercules X-1, obtained over nearly half of a 1.7 day binary orbit using the ASCA X-ray telescope and the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The GHRS resolved, for the first time, two moving emission components. One featu…