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IUE observations of the hot components in two symbiotic stars
Kafatos, M.; Michalitsianos, A. G.; Hobbs, R. W. +1 more
Recent IUE observations reveal striking differences in the UV spectra of two symbiotic stars, R Aqr and RW Hya. RW Hya is found to be an unexpectedly intense source of UV radiation. The measurements reported here demonstrate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary a…
Identification of the UV nightglow from Venus
Feldman, P. D.; Moos, H. W.; Clarke, J. T. +1 more
THE presence of atmospheric ultraviolet (UV) emission between 1,350 and 2,200 Å from the nightside of Venus was first detected by instruments on board the Mariner 5 flyby1. Recently this emission was observed by the UV spectrometer on Pioneer Venus Orbiter at 2,068 Å and identified by Stewart et al.2 as the (0, 0) Cameron ban…
Evidence of SO2 on Io from UV observations
Bertaux, J. L.; Belton, M. J. S.
A quantitative analysis of the UV spectrum of Io obtained by the IUE earth-orbiting telescope in 1978 is performed for the cases of a surface reflectivity which does not exhibit the absorption dip of pure SO2 frost and for a surface reflectivity which reproduces it exactly. The geometric albedo of Io below 320 nm is derived from the observed UV sp…
IUE observations of absorption by hot gas in the nebula NGC6888
Nussbaumer, H.; Willis, A. J.; Wilson, R. +2 more
New UV observations of Wolf-Rayet stars obtained with the IUE satellite show narrow absorption components in the highly ionized species of Si IV and C IV. In the case of the WN6 star HD 192163 each resonance transition in the above ions exhibits two components, one undisplaced in wavelength and one blueshifted. The latter components are shown to a…
IUE UV spectra of the clumpy irregular galaxy MKN297
Casini, C.; Benvenuti, P.; Heidmann, J.
Clumpy irregular galaxies are made up of 5-10 bright clumps loosely scattered in a common envelope, have excess near-UV radiation and are giant compared with classic irregular galaxies1,2. Clumps are apparently ~100 times more massive than giant H II regions such as 30 Doradus or NGC604 (ref. 3). To get an insight into their properties …
IUE observations of the symbiotic star CH Cygni during an active phase
Hack, M.
THE spectrum of CH Cygni usually has the appearance of a normal M6 III star, but at intervals of several years, it has outbursts during which it shows the characteristics of a symbiotic star, that is a blue continuum extending shortward of the B almer discontinuity, and emission lines of He I, Fe II, [Fe II], [S II], [O III]; the Balmer lines and …
IUE observations of an active region of HD206860
Blanco, C.; Catalano, S.; Marilli, E.
THE chromospheric Mg II h and k lines seem to have doubly reversed emission core in the spectra of the Sun and of solar and late type stars. In the solar spectrum the general appearance of Mg II h and k is very similar to the H and K of Ca II, but with larger intensity fluctuations. Current ideas suggest that the h and k lines are strongly sensiti…
The IUE spacecraft and instrumentation
Boggess, A.; Evans, D. C.; Carr, F. A. +7 more
The International Ultraviolet Explorer satellite operates as an astronomical observatory to provide both high and low resolution UV spectra of sources other than the Sun. The spacecraft, its instrumentation and the ground control system are described.
In-flight performance of the IUE
Gull, T. R.; Bohlin, R. C.; Boggess, A. +7 more
A report on the initial performance of the IUE satellite, launched in January, 1978, is given. Attention is given to optical performance, camera performance, background corrections, photometric performance, and data reduction. Samples of high-dispersion and low-dispersion spectra are shown. A remaining problem of proper separation of high dispersi…
COS B observation of high-energy γ radiation from 3C273
Bignami, G. F.; Hermsen, W.; Masnou, J. L. +9 more
THE discovery of a high-energy γ-ray source at α(1950) = 12h 29 min+/-6 min, δ(1950)= +3°+/-1.5° is reported here. Arguments are given for the identification with 3C273. If this identification is correct, the γ-ray luminosity of 3C273 in the energy range 50-500 MeV is 2×1046 erg s-1 for H0 = 60 km s-1 Mp…