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UV observations of the symbiotic star EG And
Pereira, Claudio Bastos
EG And is a S-type symbiotic star. Presented are UV observations made by IUE from 1978 to 1991. From these observations the electron density and the electron temperature were obtained. The size of the HeII emitting region was estimated as 7.3R⊙. Line and continuum variations confirm the binary nature of EG And.
Solar Particles Seen by ULYSSES Near 33 Degrees S
Simnett, G. M.; Tappin, S. J.
Observations of a particle event (electrons >40 keV; ions >50 keV) at heliographic mid-latitudes are presented. The particles are shown to originate from an apparently insignificant solar source and to be stored prior to release into the solar wind.
Ionization stratification in [WR] winds
Schulte-Ladbeck, Regina E.; Herald, James E.
We summarize currently available evidence for ionization stratification in the winds of [WR] stars and point out that ionization stratification may be important to explain with radiation-driven wind theory the winds of [WR] stars, while also providing an empirical tool to investigate [WR] wind structures.
Hubble space telescope observations of AGN`s in the ultraviolet: BL LAC and Q2345+007
Boyd, Patricia T.; Nelson, M. J.; Percival, J. W. +3 more
We report the first polarimetric observations in the ultraviolet of two AGN's, the blazar BL Lac and the gravitational lens candidate Q2345+007. We find strong (p>3%) and variable UV polarization in BL Lac, two of the characteristics exhibited by blazars in the visible. The polarization of BL Lac in the UV decreased significantly (from 18% to &…
Circumstellar Absorption and Emission in the Post-AGB Stars HR4049 and HD213985
Waters, L. B. F. M.; Van Winckel, H.; Waelkens, C. +1 more
The evolved C-rich low-mass stars HR 4049 and HD 213985 present variable circumstellar extinction and emission. Observations of HR 4049 strengthen the link between the far-UV extinction rise and the presence of small C-rich particles. Variability of the UV absorption bump in HD 213985 is reported here for the first time and is discussed.
New kinematic distances of NGC 7009 and BD+30°3639 from UV and radio data
Maciel, W. J.
Measurements of the equivalent width of the interstellar Lymanα line from IUE spectra in the direction of the planetary nebulae NGC 7009 and BD+30°3639 are used to infer the H column density in these directions. Hydrogen 21 cm profiles are also used in connection with the ultraviolet data so that the expected rotation velocities and distances can …
Astronomical Archives and Their Importance for Knowledge Transfer in Basic Space Science
Wamsteker, W.; Griffin, R. E. M.
We summarize the nature of modern astronomical archives with special reference to spectroscopic data archives and illustrate in which ways archives can play a role in the accelerated development of Basic Space Sciences in the developing countries. Some of the conflicting issues in the current planning of archives are addressed. Astronomical spectr…
ULYSSES Observations of Cosmic Gamma-Ray Bursts
Cline, T.; Hurley, K.; Sommer, M. +2 more
We review the current status of the Ulysses mission and summarize the results to date of the GRB experiment. This instrument detects bursts at the rate of about one every 3.5 days, and the localization data are being disseminated rapidly via the BACO-DINE and NMSU networks. The mission should operate through 2001, and future missions to Mars start…
Interpretation of a glitch observed in the very small dust grain data at halley's comet: (Letter to the Editor)
Kissel, Jochen; Utterback, Nyle G.
In a previous article describing the cloud of attogram dust particles surrounding Comet Halley, the present authors noted a sharp break in the curve of signal amplitude (related to particle size) versus distance to the comet. Arguments were given which supported the explanation that the break was instrumental rather than due to a physical structur…
A search for planetary system candidates: Northern Nearby A Stars With Dust Disks And Circumstellar Gas
Cheng, Kwang-Ping; Neff, James E.
We report on our search for possible planetary system candidates in a volume-limited sample of 62 nearby A stars. Since the evolutionary lifetimes of A stars (≤ 109 yrs) roughly correspond to the era of planet formation and subsequent "heavy bombardment" in our solar system, our study could provide valuable insight into the origin of ou…