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Quasi-simultaneous ultraviolet and optical observations of PKS 2155-304 = H 2155-304.
Maraschi, L.; Tanzi, E. G.; Tarenghi, M. +1 more
The BL Lac object PKS 2155-304 was repeatedly observed in the 1200-3000 Å band with the International Ultraviolet Explorer. The variability of the source in this band is studied in detail. The UV continua are well fitted by power laws with frequency spectral index αν varying between -0.7 and -0.9. An optical spectrum was taken within on…
IUE studies of the Wolf-Rayet binaries HD 186943 and HD 211853 duringeclipse.
Hutchings, J. B.; Massey, P.
IUE spectra have been obtained of the WR binaries HD 186943 and HD 211853 at different orbital phases. Eclipse effects are small in the UV spectra of these stars. For both systems there is an "eclipse" of the continuum flux < 1500 Å at the time of primary conjunction (WR star in front), and, for HD 186943, a comparable decrease of the strongest…
Galactic gamma radiation : the contribution from discrete sources.
Houston, B. P.; Wolfendale, A. W.
The contribution from discrete sources to the emission of galactic gamma rays is studied based on an analysis of the SAS II satellite data. The data are analyzed using cross-correlation techniques, and the results are interpreted using extensive Monte-Carlo simulations of the gamma-ray sky. These results are compared to earlier analyses based on t…
Temporal variation of the Jovian H I Lyman-alpha emission /1979-1982/
Skinner, T. E.; Durrance, S. T.; Feldman, P. D. +1 more
Observations of the Jovian H I Lyman-alpha emission have been made with the International Ultraviolet Explorer (IUE) observatory beginning in 1978 December, just before the time of the Voyager encounters, and extending through 1982 January. A nearly constant disk center brightness of about 8.5 kilorayleighs is observed for the central meridian lon…
IUE observations of five DB white dwarfs.
Wickramasinghe, D. T.
IUE spectra of five DB white dwarfs are presented and discussed. The effective temperatures deduced from the UV continua are in good agreement with recent determinations using line data in the optical region. In contrast to the situation with the λ4670 stars, there is no evidence for absorption by atomic carbon lines in the UV.
The spectra of late type dwarfs and sub-dwarfs in the near ultraviolet II. Limits to variability in MgII emission from IUE spectrophotometry.
Molaro, P.; Franco, M. L.; Beckman, J. E. +2 more
The chromospheric h and k emission cores of the G dwarfs and subdwarfs Beta Hyi (14), Zeta Tuc (5), Delta Pav (5), and Tau Cet (5) have been monitored over a period of four years using the IUE satellite long wavelength camera. A detailed statistical examination of the data has shown that no variation in h and k fluxes of less than 15 percent could…
The LMC emission line star S 22 (=HD 34664). III. Ultraviolet to infrared energy distribution.
Friedjung, M.; Viotti, R.; Muratorio, G. +1 more
New observations of the superluminous star S22 in the Large Magellanic Cloud obtained with the ultraviolet satellite IUE and in the infrared are discussed. The low resolution ultraviolet spectrum is dominated by Fe II emission and absorption lines, probably formed in an expanding cool circumstellar envelope. An attempt was made to synthesize the U…
International Ultraviolet Explorer observations of the peculiar variable spectrum of the eclipsing binary R Arae.
Kondo, Y.; McCluskey, G. E.
The eclipsing binary system R Arae = HD 149730 is a relatively bright southern system with an orbital period of about 4.4 days. It is a single-lined spectroscopic binary. The spectral class of the primary component is B9 Vp. The system was included in a study of mass flow and evolution in close binary systems using the International Ultraviolet Ex…
Non-LTE analysis of subluminous O-stars. V. The binary system HD 128220.
Kudritzki, R. P.; Gruschinske, J.; Simon, K. P. +2 more
Spectra of the binary system HD 128220 were taken in the UV and in the visual. The hot component - an O subdwarf - is analysed by means of non-LTE calculations. The cool companion has an effective temperature about 5500 ± 500K (Type G). The discussion of the stellar parameters arrives at results which agree with those derived from the mass functio…
Boss 1985 : mass loss investigation based on IUE spectra.
Reimers, D.; Che, A.
From recent IUE observations of Boss 1985 - a VV Cep type spectroscopic binary - the authors deduce the mass loss rate of the primary M star using a non-spherical three-dimensional line transfer code applied on Fe II UV mult. 9 lines. Best agreement between observed and computed line profiles is obtained using wind velocity of 10±5 km s-1