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X-ray orbital modulations in intermediate polars.
Hellier, Coel; Mason, Keith O.; Garlick, Mark A.
A systematic search of the EXOSAT observations of intermediate polars has revealed that a majority of systems show orbital-cycle X-ray modulations. The modulations are irregular, have the characteristic energy dependence of photoelectric absorption and, where it can be determined, have minima preferentially at orbital phase about 0.8. We remark on…
The chemical compositions of four B-type stars in the Small Magellanic Cloud.
Howarth, I. D.; Dufton, P. L.; Irwin, M. J. +2 more
High-resolution echelle spectra of three main-sequence B-type stars and one B-type giant in the Small Magellanic Cloud (SMC) have been obtained using the 3.9 m Anglo-Australian Telescope. These spectra have been analyzed in conjunction with IUE low-resolution spectra by using LTE model atmosphere techniques, to derive the stellar atmospheric param…
Elemental abundances in normal late-B and HgMn stars from co-added IUE spectra. II. Magnesium, aluminium and silicon.
Smith, K. C.
Atmospheric abundances of magnesium, aluminium, and silicon are derived for a sample of forty normal, superficially normal, and HgMn-type main-sequence late-B stars by spectrum-synthesis analysis of co-added high-resolution International Ultraviolet Explorer (lUE) spectra. In the normal and superficially normal stars, the abundances of these eleme…
Scattered Light in the Echelle Modes of the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope. II. Analysis of In-Flight Spectroscopic Observations
Ebbets, Dennis C.; Savage, Blair D.; Cardelli, Jason A.
We report on an analysis of observations made with the GHRS aboard the HST for the purpose of calibrating the effects of scattered light. The data were obtained during the first 2 years of flight operations as part of the Science Verification, Science Assessment Observations, and Guaranteed Time Observations programs. Both the general level of bac…
Hubble Space Telescope / Faint Object Camera Observations of the Inner Regions of the Galactic Globular Cluster M15
Paresce, F.; Ferraro, F. R.
A set of high resolution images of the core of the Galactic Globular Cluster M15 (NGC 7078) were obtained for the first time with the Faint Object Camera on the HST through the f/48-F140W, f/48-F220W and f/96-F342W ultraviolet filters. Two UV-Color-Magnitude Diagrams are presented for the approximately 300 objects measured in the 22 arcsec x 22 ar…
The Population of Massive Stars in R136 from Faint Object Camera Ultraviolet Observations
Leitherer, Claus; Nota, Antonella; de Marchi, Guido +2 more
New ultraviolet (λ ≃ 1300 Å, λ ≃ 3400 Å), HST Faint Object Camera observations have been used to derive the UV color-magnitude diagram (CMD) of R136. The main scientific goal is the study of the upper end of the stellar mass function at ultraviolet wavelengths where the color degeneracy encountered in visual CMDs is less severe.
The CMD has b…Masses and Densities of Pluto and Charion
Null, G. W.; Owen, W. M.; Synnott, S. P.
We have analyzed HST Wide Field Camera CCD images of Pluto, Charon, and a background star to observe Pluto's barycentric motion and to determine the individual masses and bulk densities of Pluto and Charon. The most fundamental new result was an accurate solution for a previously undetermined parameter, the Charon/Pluto mass ratio q; the new solut…
Detection of an Ultraviolet and Visible Counterpart of the NGC 6624 X-Ray Burster
Boksenberg, A.; Barbieri, C.; Weigelt, G. +18 more
We have detected, in images taken with the HST FOC, the UV and optical counterpart of the X-ray source 4U 1820-30 in the globular cluster NGC 6624. Astrometric measurements place this object 2 sigma from the X-ray position of 4U 1820-30. The source dominates a far-UV FOC image and has the same flux at 1400 A as was seen through the large IUE apert…
Measurements of hot plasmas in the magnetosphere of Jupiter
Simnett, G. M.; Pick, M.; Anderson, K. A. +11 more
This paper presents an overview of a number of the principal findings regarding the hot plasmas ( E ≳ 50 keV) in Jupiter's magnetosphere by the HISCALE instrument during the encounter of the Ulysses spacecraft with the planet in February 1992. The hot plasma ion fluxes measured by HI-SCALE in the dayside magnetosphere are similar to those measured…
Chemical Composition of M8 Based on IUE and Visual Observations
Dufour, R. J.; Torres-Peimbert, S.; Peimbert, M.
We present optical and IUE observations of the Hourglass Nebula which is embedded in the galactic H II region M8. By comparing the intensities of the [C III] lines λλ1907 + 1909 with that of C II λ4267, a value of t2 = 0.046±0.01 is obtained. The logarithmic abundances by number of the gaseous component for t2 = 0.046 are: H …