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IUE ultraviolet spectra and chromospheric models of HR 1099 and UX Ari.
Linsky, J. L.; Simon, T.
IUE spectra in the region 1150-3200 A of the RS CVn-type variables HR 1099 and UX Arietis are presented and analyzed in terms of chromospheric models. Measurements of Mg h and k lines and Ca II H-K and H alpha spectra are indicated which are found not to be correlated with orbital phase or radio flares and which suggest that the strong emission ar…
Ultraviolet absorption by interstellar gas near 30 Doradus
Savage, B. D.; de Boer, K. S.; Koornneef, J.
The IUE was used to obtain high-resolution far-UV spectra (1150-2070 A) of two stars in the 30 Dor H II region in the LMC. Interstellar absorption components are distinguished at +20, +220, +250, and +290 km/s. The +20 km/s component is produced by matter in the Galaxy; the high-velocity components are produced by absorbing gas near or in the LMC.…
Io: Longitudinal Distribution of Sulfur Dioxide Frost
Matson, D. L.; Nelson, R. M.; Lane, A. L. +3 more
Twenty spectra of Io (0.26 to 0.33 micrometer), acquired with the International Ultraviolet Explorer spacecraft, have been studied. There is a strong ultraviolet absorption shortward of 0.33 micrometer that is consistent with earlier ground-based spectrophotometry; its strength is strongly dependent on Io's rotational phase angle at the time of ob…
Interstellar extinction in the Large Magellanic Cloud
Nandy, K.; Willis, A. J.; Wilson, R. +3 more
Recent UV observations together with complementary visible data of several reddened and comparison stars of similar spectral types in the Large Magellanic Cloud have been used to study the interstellar extinction in that galaxy. Most of the reddened stars studied here are located within 2° of 30 Doradus and show remarkably high extinction in the f…
Detailed characteristics of the high-energy gamma radiation from PSR 0833-45 measured by COS-B.
Bignami, G. F.; Hermsen, W.; Masnou, J. L. +11 more
A series of COS-B observations of the high-energy gamma-ray emission from PSR 0833-45 has been combined to derive detailed temporal and spectral characteristics of this source. The gamma-ray period of the pulsar was determined for the observations spanning the time interval October 1975 to June 1977. The variation of the period with time can be ex…
Ultraviolet observations of the Cygnus Loop
Raymond, J. C.; Dupree, A. K.; Black, J. H. +2 more
The analysis of IUE observations of a filament on the western edge of the Cygnus Loop yields a shock velocity of about 130 km/sec, significantly higher than the velocity estimated from the optical spectrum. This velocity together with the high forbidden O III/H-beta ratio reported by Miller (1974) indicates that much of the hydrogen recombination …
Highly-ionized species in the interstellar medium.
Raymond, J. C.; Dupree, A. K.; Hartmann, L. W. +1 more
Interstellar absorption lines have been observed toward 25 stars with the International Ultraviolet Explorer satellite. Results are presented for observations of interstellar lines of C III, C IV, N V, Si III, and Si IV. Strong lines of Si IV or C IV are seen toward 11 stars. The strengths of these lines are inconsistent with their formation in th…
The boundary line in the H-R diagram for stellar chromospheres and the theory of convection.
Boehm-Vitense, E.; Dettmann, T.
Ultraviolet emission-line spectra of A, F, and early G stars have been observed with the International Ultraviolet Explorer. For supergiants, classical chromospheric and transition-layer emission is seen only on the red side of the Cepheid instability strip. For luminosity classes III-V, chromospheric emission can be detected for spectral types F2…
COS-B observations of high-energy gamma-ray emission from the Orion cloud complex.
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +11 more
Emission of high-energy gamma rays (between 70 and 5000 MeV) has been observed from the direction of the Orion cloud complex by the COS-B satellite. The emission is resolved and the existence of structure is apparent within the excess with two maxima coinciding with L 1630 and L 1641, i.e. the northern and the southern major clouds in the complex.…
Far-ultraviolet spectrophotometry of supernova remnants - Observations and astrophysical interpretation
Benvenuti, P.; Dopita, M.; Dodorico, S.
Far UV spectra obtained with IUE in the supernova remnants Cygnus Loop in the galaxy and N49 and N63 in the LMC have been interpreted using the radiating shock-wave models. Some elemental depletion and a range of shock velocities (approximately 80-130 km/s) are needed to give an adequate description of the observed spectra. Carbon is anomalous, a …