Search Publications
Time variability in the UV resonance lines of the cataclysmic variables MU Cen, AH HER and QU Car.
Knigge, C.; Drew, J. E.; Hoare, M. G. +1 more
We present a time-variability study of the uV resonance lines Nv 1240, Si iv 1397 and C iv 1549 in the dwarf novae AH Her and MU Cen and the nova-like variable QU Car. The main findings are as follows. (i)Virtually no variation can be seen in our data for MU Cen. (ii) AH Her shows velocity shifting of its resonance lines, with semi-amplitudes rang…
Dust streams from comet Shoemaker-Levy 9?
Hamilton, D. P.; Horanyi, M.; Polanskey, C. +3 more
In 1991 and 1992, the dust detector onboard the Ulysses spacecraft detected several dust streams apparently originating from the jovian system. The timing and measured speeds of the final two dust streams are compatible with dust from comet Shoemaker-Levy 9's (SL9) disruption in 1992. Our further investigations of stream characteristics and dust a…
An Ultraviolet-Visible Investigation of the Globular Cluster NGC 1851
Cheng, Kwang-Ping; O'Connell, Robert W.; Bohlin, Ralph C. +8 more
Two-color ultraviolet images of the globular cluster NGC 1851 were obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 Spacelab mission. A total of 133 stars are detected at 2490 A and 74 stars at 1520 A. An ultraviolet color-magnitude diagram based on the 46 well-photometered stars that appear in both images is …
High-Resolution Imaging of the Pluto-Charon System with the Faint Object Camera of the Hubble Space Telescope
Barbieri, C.; Hook, R. N.; Sparks, W. B. +8 more
Images of the Pluto-Charon system were obtained with the Faint Object Camera (FOC) of the Hubble Space Telescope (HST) after the refurbishment of the telescope. The images are of superb quality, allowing the determination of radii, fluxes, and albedos. Attempts were made to improve the resolution of the already diffraction limited images by image …
The ``Monochromatic Density Diagnostic'' Technique: First Detection of Multiple Density Components in the Chromosphere of alpha Tauri
Judge, P. G.
Emission line profiles of the red giant alpha Tau, obtained by Carpenter et al. (1991) using the echelle and medium dispersion gratings of the Goddard High Resolution Spectrograph are re-examined. Ratios of monochromatic flux densities of lines of the C II) 2s2 2p(2)P0 goes to 2s2p2 (4)P multiple near 2325 A, well-…
Theoretical Modeling of GHRS Observations of the Of/WN-Type Star R136a5
Hubeny, Ivan; Heap, Sara R.; Lanz, Thierry +1 more
We present a theoretical analysis of the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph (GHRS) spectrum of R136a5, an O3fWN star in the R136a cluster in 30 Doradus. Using non-LTE extended and expanding model atmospheres, we find a surprisingly high mass-loss rate dot-M = 1.8 +/- 0.5 x 10-5 solar mass/yr and an effecti…
Ultraviolet and Radio Observations of the Young Rapidly Rotating k0 Dwarf Star HD197890
Carpenter, K. G.; Robinson, R. D.; Slee, O. B. +2 more
We present the results of UV observations taken with the International Ultraviolet Explorer (IUE) satellite and microwave observations obtained with the Australia Telescope during an observing campaign of the rapidly rotating K0 dwarf star III) 197890, nicknamed `Speedy Mic'. This star was recently recognized as a powerful, transient EUV source by…
Correlated Optical and Radio Structure in the QSO 1302-102
Hutchings, J. B.; Morris, S. C.; Lister, M. L. +1 more
We present new optical imaging in two broad-band colors ofthe z=0.29 bright QSO 1302-102, obtained with the Wide Field Camera of the Hubble Space Telescope. We have performed deconvolution on the HST data, previously published CFHT HRCam data, and the combined data. The structure and brightness are measured of an extended knot 2.3 arcsec from the …
Asymmetries in the Io plasma torus
Kaiser, M. L.; Desch, M. D.; Farrell, W. M.
Using Ulysses radio wave data taken during the 1992 Jupiter encounter, we conclude that there are significant large and small spatial scale azimuthal asymmetries at high latitudes in the Io plasma torus. During a period of time near perijove when the spacecraft motion was predominantly in the azimuthal direction and was relatively fixed in both la…
Multiwavelength observations of RV Tauri stars III. R Scuti
Evans, A.; Lloyd Evans, T.; Rawlings, J. M. C. +7 more
We present ultraviolet, optical and infrared observations of the RV Tauri star R Sct. We argue that changes in the ultraviolet spectrum with pulsational phase cannot be due to changes in effective temperature and gravity alone, and that variable circumstellar extinction in the form of Rayleigh scattering is also necessary. The intrinsic ultraviole…