Search Publications
A Cluster of Nascent Galaxies at Z = 2?
Dressler, Alan; Oemler, Augustus, Jr.; Gunn, James E. +1 more
On a 6 hr Wide Field Camera exposure with the Hubble Space Telescope of the rich cluster CL 0939+4713, we have identified an apparent cluster of ~30 faint, extended objects with magnitudes 22 < r < 25. The objects are typically 1" in size with bright central regions only a few tenths of an arcsecond in size, and are distributed over a region…
Excitation Rate Coefficients and Line Ratios for the Optical and Ultraviolet Transitions in S II
Cai, Wei; Pradhan, Anil K.
New calculations are reported for electron excitation collision strengths, rate coefficients, transition probabilities, and line ratios for the astrophysically important optical and UV lines in S II. The collision strengths are calculated in the close coupling approximation using the R-matrix method. The present calculations are more extensive tha…
UV spectral variability in the Herbig AE star HR 5999. 11: The accretion interpretation
Grady, C. A.; Perez, M. R.; The, P. S.
We report recent IUE high- and low-dispersion observations with the IUE long wavelength camera (LWP) and short wavelength camera (SWP) of the Herbig Ae star HR 5999. We have found a dramatic change in the structure of the Mg II h and k lines (2795.5, 2802.7 Å) along with some continuum flux excesses especially at the short end of the SWP camera. L…
Low-frequency electromagnetic plasma waves at comet P/Grigg-Skjellerup analysis and interpretation
Coates, A. J.; Neubauer, Fritz M.; Glassmeier, Karl-Heinz +1 more
The propagation and polarization characteristics of low-frequency electromagnetic wave fields near comet P/Grigg-Skjellerup (P/GS) are analyzed using magnetic field and plasma observations obtained by the Giotto magnetometer experiment and the Johnstone plasma analyzer during the encounter at the comet on July 10, 1992. The results have been physi…
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…