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The ionization structure of the ring nebula. II. Ultraviolet observations.
Barker, T.
Good agreement is found for O and N abundances, and the importance of charge-transfer reactions to the ionization of Ne is confirmed, in UV observations of emission line intensities for four positions in the Ring Nebula that have been previously studied optically. It is noted that the C(2+) abundance inferred from the optical 4267 A recombination …
Ultraviolet absorption by interstellar gas near the LMC star HD 36402in the interstellar bubble N51D.
de Boer, K. S.; Nash, A. G.
Four interstellar absorption components associated with the immediate surroundings of the star are found in UV, high-dispersion IUE spectra of the LMC star HD 36402 in the N51D nebulosity. The 305 km/sec absorption is found to originate in low-density, 10,000 K gas, and the density and velocity structures agree with that derived from visual emissi…
Angular diameters, effective temperatures, radii and luminosities of 03, 04 and 05 stars.
Underhill, A. B.
UV and visible photometry is used to determine the effective temperatures, angular diameters, linear radii and luminosities of 24 O3, O4, and O5 stars. No correlation is found between effective temperatures, which ranged from 24,800 K to 63,000 K, and spectral type or luminosity class for the early O stars. Since conditions in the outer atmosphere…
High-energy γ-ray light curve of PSR0531 + 21
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +8 more
The Crab pulsar (PSR0531 + 21) was one of the earliest identified sources of high-energy γ radiation1-6. As such it was selected as the first object of detailed study by ESA's γ-ray astronomy satellite COS B, launched in August 1975. The experiment and mission have been described elsewhere7. In the first 6 yr of operation COS…
The gaseous galactic halo as infrared from the line spectra of the galaxies Markarian 509 and Fairall 9.
York, D. G.; Cowie, L. L.; Blades, J. C. +3 more
Narrow interstellar absorption lines of S II 1259.52, Si II 1260.42, and Fe II 1608.46 due to gas in the disk and the halo of the Galaxy have been detected in the spectrum of the Seyfert galaxy Mrk 509 with the International Ultraviolet Explorer. This gas is also seen at higher resolution in the Ca II and Na I absorption lines in two components at…
Chromospheric MG II emission in A5 to K4 main sequence stars from high resolution IUE spectra.
Blanco, C.; Catalano, S.; Marilli, E. +1 more
Observations of the emission cores of the Mg II resonance doublet for 11 main sequence stars in the spectral type range A5-K5 obtained with the IUE satellite at 0.2 A resolution are discussed. Calibrated observed fluxes are used to evaluate the Mg II chromospheric losses as they correlate with effective temperature convection and rotation and othe…
The ultraviolet continuous and emission line spectra of the Herbig-Haro objects HH 2 and HH 1.
Nemec, J. M.; Boehm-Vitense, E.; Cardelli, J. A. +1 more
Recent studies of the continuous spectrum of Herbig-Haro (HH) objects at optical and near-infrared wavelengths and the observation of continuous radiation in the ultraviolet have shown an unexpectedly steep increase of the flux toward shorter wavelengths. The present investigation provides the results of ultraviolet observations of HH 2. The obtai…
The far-ultraviolet spectra and geometric albedos of Jupiter and Saturn
Feldman, P. D.; Moos, H. W.; Clarke, J. T.
Spectra and geometric albedoes in the range 1200 to 1940 A are compiled for Jupiter and Saturn on the basis of IUE observations. The spectra of both planets are dominated by H Lyman-alpha emission line at 1216 A, although absorption bands of C2H2 are apparent at longer wavelengths, particularly in the spectrum of Saturn, and the C I line at 1657 A…
Simultaneous observations of the BL Lacertae object I ZW 187.
Pollock, J. T.; Huggins, P. J.; Bregman, J. N. +15 more
Two sets of simultaneous spectra consisting of data obtained with radio, IR, optical, UV and X-ray telescopes were obtained 10 months apart for the X-ray bright BL Lac object IZw 187. In addition, nonsimultaneous observations were made in several of the aforementioned observing bands in order to detect flux variations and galactic light contaminat…
The physical conditions within the poly-polar nebula NGC 6302 - III.
Walsh, J. R.; Meaburn, J.; Barral, J. F. +1 more
IUE observations of the ultraviolet emission lines and continuum from the wind-driven poly-polar nebula NGC 6302 have been combined with those obtained of the visible emission lines to investigate the physical parameters of the ionized gas. Several relationships consolidate the view that this nebula is predominantly ionized radiatively by a very h…