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IUE observations of mass ejection by the close binary system AO Cas.
Kondo, Y.; McCluskey, G. E.
It is noted that 11 high-resolution spectra in the far-ultraviolet and two high-resolution spectra in the mid-ultraviolet were obtained. A high-velocity stellar wind exists as indicated by narrow shortward-displaced absorption features superposed on the P Cygni lines of N V, Si IV, and C IV. Absorption lines caused by N IV and C III are present an…
Transition region structure in F dwarfs.
Saxner, M.
Strong transition region line emission detected in the IUE spectra of two F dwarfs is discussed. The corresponding surface fluxes are found to be comparable to those of active binaries, such as RS CVn-systems. Line flux ratios formed from the multiplets Si IV 1394 A + 1403 A, C IV 1549 A, and N V 1240 A are used in deriving the structure of the tr…
HR 4511 : a probable cepheid with a supergiant-like hot companion.
Parsons, S. B.
IUE observations have shown HR 4511 to have an early B-type companion with a strong stellar wind. Fitting the energy distribution of the system from far-UV to middle-IR yields a difference of about 3.2 mag at the V passband. Since HR 4511 is in the small cluster Stock 14 and has M(V) = -7.8, M(V) for the secondary is about -4.6, which is only slig…
IUE observations of eight OB stars in NGC 2244 : ultraviolet continuaand extinction.
Massa, D.; Conti, P. S.
Low-resolution IUE ultraviolet continuum observations of O and B stars in the young open cluster NGC 2244 are presented. When only relative energy distributions are considered, thereby eliminating any dependence on reddening corrections or absolute energy calibrations, it is found that the ultraviolet energy distributions of the O stars have signi…
Evidence for autoionization and dielectronic recombination of SI II in the atmospheres of B-type stars.
Underhill, A. B.
Observations are reported demonstrating that both of the 3s3p3d 2F0 levels of Si II autoionize in the atmospheres of B-type stars. A justification is given for concluding that the 2F05/2 level which lies below the laboratory position for the 3s2(1S) limit of Si II, autoio…
Bolometric corrections of silicon stars.
North, P.
Low-dispersion spectrograms of two peculiar stars and of two normal ones were obtained with the IUE satellite in both wavelength ranges. Semi-empirical bolometric corrections were estimated from the observed ultraviolet fluxes and from theoretical fluxes best fitting the observed Geneva color indices.
IUE observations of X Per, the proposed optical counterpart of the X-ray source 4U 0352+30.
Bianchi, L.; Bernacca, P. L.
The O 9.5 (III-V) pe star X Persei, proposed optical counterpart of the X-ray source 4U 0352+30, has been observed on October 14, 1978, with the SWP Camera on board the IUE satellite in the low and high resolution modes. The ultraviolet continuum, in the range 1000-1900 A, can adequately be fitted to the emergent flux from a model atmosphere havin…
IUE observations of V1331 Cyg.
Mundt, R.; Appenzeller, I.; Chavarria, C. +2 more
Low dispersion IUE spectrograms (at wavelengths of 2200-3200 A) of the unusual T Tauri star V 1331 Cyg have been obtained. The observed UV flux is consistent with the assumption that V 1331 Cyg has a photosphere corresponding to a spectral type near F 0. As in the blue to red spectral range, the observed UV line spectrum (dominated by very strong …
Ultraviolet Observations of the X-Ray Sources in the Eta-Carinae Nebula
Macchetto, F.; Viotti, R.; Cassatella, A. +1 more
η Car is surrounded by a dense nebula ejected during the last 150 years. The Einstein satellite recently detected intense X-ray emission from η Car and its nebula indicating the existence of efficient gas heating processes. Ultraviolet observations with IUE confirmed the presence of hot gas in the condensation S of the nebula and in η Car. Possibl…
Low-Latitude Galactic γ -ray Emission: A Probe, not a Proof
Bignami, G. F.
The emission of high energy (above 70 MeV) γ -rays from the galactic disc has been mapped by the COS-B mission with unprecedented detail. The results for |b| < 15 degrees are seen to contain evidence of structures correlated with the Galaxy on various scales, from the `grand design' down to granularities, showing that the diffuse interstellar m…