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The Early Ultraviolet Spectral Evolution of Nova Cygni 1992
Ake, T. B.; Shore, Steven N.; Sonneborn, George +2 more
We report on the high resolution ultraviolet line profile evolution of Nova Cygni 1992 using the International Ultraviolet Explorer (IUE) satellite and the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST). Our observations cover the period from discovery in 1992 February through 1993 April. The initial expansion velo…
Synthetic UV Lines of Si IV, C IV, and He II from a Population of Massive Stars in Starburst Galaxies
Robert, Carmelle; Heckman, Timothy M.; Leitherer, Claus
We present the first results of our study of the massive star population in starburst galaxies based on UV data. We have synthesized the Si IV 1400, C IV 1550 and He II 1640 lines for both a continuous and an instantaneous burst of star formation with approximately solar chemical composition. Our code uses the latest generation of stellar evolutio…
A model for the 89 Herculis system.
Waters, L. B. F. M.; Mayor, M.; Trams, N. R. +1 more
We report new radial velocity measurements of the F2 supergiant 89 Her that confirm the binary nature of this star. A period search yields an orbital period of 288.4 +/- 0.7 days, in close agreement with earlier results. We also present intermediate resolution spectra in the wavelength range 3500 - 11,000 A, with numerous emission lines. We use th…
Counterstreaming suprathermal electron events upstream of corotating shocks in the solar wind beyond ∼2 Au: Ulysses
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +3 more
Enhanced fluxes of suprathermal electrons are commonly observed upstream of corotating forward and reverse shocks in the solar wind at heliocentric distances beyond ∼2 AU by the Los Alamos plasma experiment on Ulysses. The average duration of these events, which are most intense immediately upstream from the shocks and which fade with increasing d…
Detection of Boron, Cobalt, and Other Weak Interstellar Lines toward zeta Ophiuchi
Lambert, D. L.; Federman, S. R.; Gilliland, R. L. +1 more
Numerous weak lines from interstellar atomic species toward Zeta Ophiuchi were observed with the Goddard High-Resolution Spectrograph. Of particular note are the first interstellar detection of cobalt and the detection of boron in this sight line. These measurements provide estimates for the amount of depletion for the two elements. Boron, a volat…
On the relative C,N,O abundances and the evolutionary status of yellow symbiotic stars.
Nussbaumer, H.; Schmid, H. M.
Symbiotic binaries consist of a cool giant and a hot radiation source, which is ionizing the nebula associated with the system. Yellow symbiotic stars can be divided according to their IR colors into s-type (stellar) and d'-type (dust) systems. The s-types are relatively narrow systems, with orbital periods of several hundred days. They contain hi…
First results from the Giotto magnetometer experiment during the P/Grigg-Skjellerup encounter
Glassmeier, K. -H.; Neubauer, F. M.; Pohl, M. +9 more
The Giotto magnetic field experiment has provided the first magnetic field data on the interaction between the solar wind and a low gas production comet, P/Grigg-Skjellerup. Waves produced by ion pick-up instabilities have been observed throughout the interaction region with particularly simple waveforms at large distances and a rich phenomenology…
Spectrophotometry of Wolf-Rayet Stars. I. Continuum Energy Distributions
Massey, Philip; Vacca, William D.; Conti, Peter S. +2 more
All available low-resolution IUE spectra are assembled for Galactic, LMC, and SMC W-R stars and are merged with ground-based optical and NIR spectra in order to collate in a systematic fashion the shapes of these energy distributions over the wavelength range 0.1-1 micron. They can be consistently fitted by a power law of the form F(lambda) is app…
Ultraviolet Transitions of Low Condensation Temperature Heavy Elements and New Data for Interstellar Arsenic, Selenium, Tellurium, and Lead
Federman, S. R.; Lambert, David L.; Cardelli, Jason A. +1 more
On the Lyman-Alpha Emission of Starburst Galaxies
Valls-Gabaud, David
Nearby starburst galaxies have consistently shown anomalous Lyα/Hβ ratios. By reanalyzing the published IUE/optical observations, we show that most starbursts present a normal Lyα emission, consistent with case B recombination theory, provided extinction laws appropriate to their metallicities are used. This implies that extinction is more importa…