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Rapid Mass-Loss Transients in VV Cephei
Stencel, Robert E.; Potter, Daniel E.; Bauer, Wendy H.
Biweekly ultraviolet observations of the red supergiant-hot dwarf binary, VV Cephei during 1991, obtained near third quadrature, have revealed the existence of short-term continuum variations. We infer these are superposed on an underlying emission-line spectrum. The viewing geometry of this long period system suggests we are seeing a process asso…
Ordinary and Z-mode emissions from the Jovian polar region
MacDowall, R. J.; Kaiser, M. L.; Desch, M. D. +2 more
The Ulysses Unified Radio and Plasma (URAP) experiment has detected a new component of Jupiter's radio spectrum in the frequency range from about 10 to 30 kHz. This component is emitted in the magnetoionic ordinary mode from a localized corotating source in the northern polar region. The source is centered at system III longitude 208°, near the me…
Ultraviolet Properties of Individual Hot Stars in Globular Cluster Cores. I. NGC 1904 (M79)
Altner, B.; Matilsky, T. A.
As part of an observing program using the IUE satellite to investigate the properties of stars within the cores of Galactic globular clusters, we have obtained three spectra of the cluster NGC 1904 (M79). All three were long-integration-time, short-wavelength (SWP) spectra obtained at the so-called 'center-of-light', and all three showed evidence …
ROSAT-pointed observations of two gamma-ray burst error boxes.
Hurley, K.; Motch, C.; Kouveliotou, C. +3 more
We present ROSAT observations of two gamma-ray burst error boxes and of one possible optical transient source. No point sources were detected and a comparison is made with previous observations of the same objects (Boer et al. 1988, 1991). We interpret the data in the context of gamma-ray burst models that invoke galactic neutron stars. Although r…
Luminosities for Two Yellow Supergiants: Non-variables and the Instability Strip
Evans, Nancy R.
The luminosities for two yellow supergiants HD 183864 and Psi And = HD 223047 are determined from the IUE spectra of their hot companions. The absolute magnitudes of HD 183864 and HD 223047 are -2.3 and -2.1 mag, respectively, and their companions have spectral types of A0.0 V and B8.8 V. The companion of Psi And is compatible with the orbital mot…
Sulfur abundances in the solar wind measured by SWICS on Ulysses
Geiss, J.; Galvin, A. B.; Ipavich, F. M. +4 more
One of the nine experiments on Ulysses (launched October, 1990), the Solar Wind Ion Composition Spectrometer, utilizes an energy per charge deflection system along with time of flight technology to uniquely determine the mass and mass per charge of solar wind particles. Thus the composition of various solar wind types can be analyzed. Using the SW…
Plasma electron signatures of magnetic connection to the Jovian bow shock: Ulysses observations
Balogh, André; Moldwin, Mark B.; Scime, Earl E. +3 more
Ulysses plasma electron observations of bidirectional and enhanced unidirectional electron heat fluxes within 4500 RJ (0.8 a.u. or 3 months on either side of closest approach) of Jupiter are presented as evidence for the magnetic connection of the spacecraft to the Jovian bow shock. These bursts of suprathermal electrons (> 30 eV) ar…
Tracing the roots of interstellar mid-infrared emission.
Desert, F. -X.; Jenniskens, P.
An attempt is made to link components of the interstellar extinction curve to mid infrared emission of interstellar dust. The IRAS mid-infrared emission has been sought for in the direction to all early type stars for which IUE extinction curves have been published. In 44 lines of sight we were able to obtain well defined colours. By comparing the…
Ultraviolet observations of the circumstellar envelope of alpha1 HER in the line of sight of alpha2 Her.
Reimers, D.; Thiering, I.
We establish an empirical model of the circumstellar envelope of the red giant α1 Her, using spectroscopic UV and optical observations of its visual binary companion α2 Her. In particular, we obtained high-resolution IUE long wavelength spectra of α2 Her, in which for the first time α1 Her could be exclu…
Coordinated UV-optical observations of quasars : the evolution of the Lyman absorption.
Cristiani, S.; Giallongo, E.; Buson, L. M. +2 more
The average flux decrement shortward the Lyα emission, due to the well-known "forest" of absorptions, has been measured in the spectra of 8 quasars. Quasi-simultaneous optical and IUE observations of the two low redshift quasars PKS 0637-75 (z = 0.654) and MC 1104+16 (z = 0.632) have been carried out, obtaining relatively high S/N, spectrophotomet…