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The ultraviolet spectrum of the center of M 31.
Welch, G. A.
A total of twelve long-exposure low-resolution IUE images have been used to study the spectrum and surface brightness distribution of the ultraviolet radiation within the central 50 pc of M31. The presence of weak absorption features near 1300 A demonstrates that the radiation of the well-known spectral upturn below 2000 A does not originate in yo…
Detection of auroral hydrogen Lyman-alpha emission from Uranus.
Clarke, J. T.
A series of observations of Uranus obtained with the short-wavelength spectrograph of the International Ultraviolet Explorer Observatory in 1982 April and June have revealed unexpectedly strong H Lyman-alpha emission which varied between 430 and 850 rayleighs in observed disk-averaged brightness over the course of these observations. The variabili…
The ultraviolet bands of the CO2/plus/ ion in comets
Feldman, P. D.; Weaver, H. A.; Festou, M. C.
Eight comets are studied with the International Ultraviolet Explorer spectrographs. The existence of the CO2(plus) ion in a comet is confirmed through the presence of the 2890 A doublet in at least three of these objects. Spatial and spectral resolution obtained in comets Bradfield (1979 X) and Seargent (1978 XV) permit a discussion of the product…
IUE spectra of clumpy irregular galaxies
Casini, C.; Benvenuti, P.; Heidmann, J.
IUE spectra at short wavelengths were obtained for two clumpy irregular galaxies, Mkn 8 and Mkn 325. Clumps could be resolved across the slit. Statistics now available on 10 clumps show that, on average, each clump radiates 100 times more at 155 nm than the giant H II region 30 Doradus and contains 0.00007 early-type stars. This confirms the hypot…
Evolution of chromospheres and coronae in solar mass stars : a far-ultraviolet and soft X-ray comparison of Arcturus (K2III) and alf CEN A (G2V).
Linsky, J. L.; Simon, T.; Ayres, T. R.
IUE far-UV and Einstein Observatory soft X-ray observations for the red giant Arcturus and the nearby yellow dwarf Alpha-Centauri A, which are archetypes of solar mass stars in different stages of evolution, are compared. Evidence is found for neither coronal soft X-ray emission from the red giant, at surface flux levels of only 0.0006 that detect…
The ultraviolet spectra of the nuclei of spiral galaxies. I - NGC 4594, 3031, 5194 and 4258
Efstathiou, G.; Gondhalekar, P. M.; Ellis, R. S.
Absolute spectrophotometry is presented from 1250 A to 4 microns within the same aperture in the nuclei of four spiral galaxies. The light distributions within the apertures are often irregular but no positive evidence for internal reddening has been found, except possibly for NGC 3031. The absence of any reddening features could still be consiste…
IUE observations of SI and C lines and comparison with non-LTE models.
Kamp, L. W.
Classical model atmosphere techniques are applied to analyze IUE spectra, and to determine abundances, effective temperatures and gravities. Measurements of the equivalent widths and other properties of the line profiles of 24 photospheric lines of Si II, Si III, Si IV, C II, C III and C IV are presented in the range of 1175-1725 A for seven B and…
The low state of AM HER : observations from 0.12 to 10 microns.
Raymond, J. C.; Szkody, P.; Capps, R. W.
Observations of AM Her during a low state over a wavelength range from 0.12 to 10 microns are reported. These include IUE ultraviolet spectra, light curves at U, B, V, R, J, H, K, and magnitudes at L, M, and N. The UV observations reveal a nearly Rayleigh-Jeans continuum spectral distribution and broad Lyman-alpha absorption from a hot (effective …
Physical conditions in the accretion disk of V603 Aql.
Lambert, D. L.; Shields, G. A.; Ferland, G. J. +2 more
Ultraviolet and optical spectra of the old nova V603 Aql are discussed. The UV-optical continuum is dominated by emission from the accretion disk. Emission lines from ions of H, He, C, N, and O are identified. These lines are probably formed in a circumstellar shell with radius comparable to the binary separation, density ten billion per cu cm, an…
The violent interstellar medium associated with the Carina Nebula. I.The line of sight toward HD 93205.
Paul, J. A.; Pettini, M.; Laurent, C.
Four high velocity and two low velocity components have been identified by the analysis of interstellar absorption lines in high resolution spectra of HD 93205. The chemical composition and physical conditions of the different regions are discussed in light of UV, optical and radio observations, and the two main high velocity components are found …