Search Publications
Network Synthesis Localization of Two Soft Gamma Repeaters
Cline, T.; Kouveliotou, C.; Sommer, M. +5 more
We introduce the method of 'network synthesis,' which allows the detection of very weak gamma-ray transient signals in the data of the Ulysses gamma-ray burst (GRB) experiment from repeating sources. It consists of defining a grid of alpha, delta values, and for each BATSE detection of a burst from a soft gamma repeater, predicting the arrival tim…
The Far-Ultraviolet Dust Albedo in the Upper Scorpius Subgroup of the Scorpius OB2 Association
Gordon, Karl D.; Witt, Adolf N.; Carruthers, George R. +2 more
During NRL's Far Ultraviolet Cameras experiment on STS-39, four images of the giant reflection nebula encompassing the Upper Scorpius subgroup of the Sco OB2 association were obtained in two ultraviolet bandpasses with lambdaeff = 1362 A and 1769 A. From these images and IUE and TD-1 stellar spectra, the ratio of nebular to stellar flux…
V348 Sagittarii : analysis of the [WC12] stellar spectrum
Hamann, W. -R.; Leuenhagen, U.
The Wolf-Rayet type spectrum of the highly variable V 348 Sgr, central star of a planetary nebula, is analyzed. An optical spectrum during maximum shows various emission and P-Cygni features, which indicate an expansion of the atmosphere. In order to assess the stellar and atmospheric parameters of this Population II object, a high resolution opti…
Dust formation in Nova Cassiopeiae 1993 seen by ultraviolet absorption
Sonneborn, G.; Hauschildt, P. H.; Shore, S. N. +2 more
The clouds of gas in interstellar space also contain grains of dust, whose properties and origins have been the focus of debate for decades. Some dust formation has been assumed to take place in novae explosions1-5, as was first implied by the observation of a steep decrease in the amount of light emitted by the nova1,2 DQ He…
The morphology of the north Jovian ultraviolet aurora observed with the Hubble Space Telescope
Paresce, Francesco; Prange, Renee; Gerard, Jean-Claude +1 more
A series of six images covering a complete rotation of the north polar region of Jupiter were obtained in February 1993 with the Faint Object Camera on board the Hubble Space Telescope. These images provide the first global picture of the morphology of the Jovian ultraviolet aurora observed from Earth orbit. The camera passband was centered near 1…
The contribution of small particles to the extinction curve.
Boulanger, F.; Gry, C.; Prevot, M. L.
We have searched for a correlation between the strength of the 12 and 25 µm emission measured by IRAS and the UV extinction curve for stars behind the Chamaeleon molecular complex. We find that the mid-IR emission is correlated with the area of the 2200 A bump but bump carriers are not fully depleted in matter with no mid-IR emission. We obs…
Long-term periodic variability in UV absorption lines of the Be star γ Cassiopeiae: on the relation with V/R variations in the Hβ line.
Telting, John H.; Kaper, Lex
We present a quantitative study of the variability in ultraviolet resonance lines of NV, SiIV and CIV of the Be star γ Cas. For this purpose we used IUE spectra obtained over a period of eleven years. Variability occurs in the form of discrete absorption components (DACs), which are formed in the fast-outflowing radiatively driven part of the stel…
Observing Stellar Coronae with the Goddard High Resolution Spectrograph. I. The dMe Star AU Microscopii
Carpenter, K. G.; Linsky, J. L.; Shore, S. N. +11 more
We report on an observation of AU Mic taken with the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The data consist of a rapid sequence of spectra covering the wavelength range 1345-1375 A with a spectral resolution of 10,000. The observations were originally intended to search for spectral variations during flares…
The early Spectral Evolution of Nova Cassiopeiae 1993
Shore, Steven N.; Sonneborn, George; Hauschildt, Peter H. +3 more
In this paper we describe the evolution of Nova Cas 1993 over the first two months of its outburst. We present an ultraviolet light curve that covers the period from announcement to just after dust began forming in the ejecta (1994 Feb. 15) and International Ultraviolet Explorer (IUE) spacecraft constraints forced us to halt our observations. We h…
Auroral Lyman α and H2 bands from the giant planets: 1. Excitation by proton precipitation in the Jovian atmosphere
Prange, Renee; Rego, Daniel; Gerard, Jean-Claude
This paper is part of a work aimed at modeling the ratio of the observed Jovian auroral intensity at H Lyman α and in the H2 Lyman and Werner bands and interpreting them as diagnostic of the incident magnetospheric particle species and energy. The work is planned in three steps: (1) modeling of the volume excitation rate, (2) modeling o…