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Ultraviolet spectrum synthesis of the helium white dwarf Ross 640.
Cottrell, P. L.; Greenstein, J. L.
The UV spectrum of the He-rich white dwarf Ross 640 was used to derive Mg, Si, and Fe abundances by a spectrum synthesis technique. The values obtained were: Mg/He = 6.8 x 10 to the -8th; Si/He = 3.2 x 10 to the -8th; Ca/He = 7.6 x 10 to the -10th; and Fe/He = 2.0 x 10 to the -9th. The abundances indicate the operation of diffusion processes withi…
Ultraviolet spectroscopic observations of VV Cep.
Dupree, A. K.; Holm, A. V.; Black, J. H. +1 more
Observations with the International Ultraviolet Explorer satellite (IUE) of the recent egress of the eclipsing binary VV Cep(M2Iabep + B) are presented. Egress in the ultraviolet lagged behind the visible egress by 2 to 3 months, as a result of higher opacity of the M star atmosphere in the ultraviolet. Shortly after visible egress, the low-disper…
The observations of the X-ray source HZ Her/Her X-1.
Davis, R. J.; Howarth, I. D.; Hammerschlag-Hensberge, G. +15 more
The results of a campaign of monitoring HZ Her with the IUE satellite are presented. The spectrum and light variation outside of eclipse are consistent with the Milgrom and Salpeter model for emission from the X-ray heated photosphere of the primary. Near eclipse there is UV flux in excess of the prediction of the heated photosphere model, which s…
The detection of a companion star to the Cepheid variable eta Aql.
Doschek, G. A.; Mariska, J. T.; Feldman, U.
Ultraviolet spectra have been obtained with IUE of the classical Cepheid Eta Aquilae at several phases in the 7.18 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less than about 1600 A does not vary with phase.…
IUE observations of the peculiar M giant HD 4174.
Sahade, J.; Stencel, R. E.
Ultraviolet spectra of the peculiar M giant HD 4174, which may possess a significant magnetic field, are shown to exhibit numerous high-excitation emission lines and no background continuum. Ionization equilibrium temperatures for species observed range from 6000 K (Mg II) up to 200,000 K (N v). Density diagnostics using line ratios indicate elect…
The abundance of carbon and magnesium in the Orion Nebula
Patriarchi, P.; Perinotto, M.
The Orion nebula has been observed in two positions with IUE (International Ultraviolet Explorer) in the low-resolution mode (about 7 A) and in the spectral range 1150-3200 A. Emission lines of C II, C III, O II, and He I have been measured and used to determine what is probably the first reliable abundance of carbon in H II regions. The logarithm…
Electron densities for six planetary nebulae and HM SGE derived fromthe CIII lambda 1907/1909 ratio.
Feibelman, W. A.; Hobbs, R. W.; Boggess, A. +1 more
Electron densities for IC 418, NGC 6572, IC 1297, NGC 3242, NGC 6818, NYC 3211, and HM Sagittae derived from high-dispersion IUE C III] spectrograms are consistently higher than those derived from either surface brightness measurements or forbidden line intensity ratios in the visible. The nebulae were selected for a range of excitation classes fr…
Ultraviolet, visual, and infrared observations of the peculiar Be star HD 45677.
Savage, B. D.; Sitko, M. L.
The peculiar Be star HD 45677 was observed at low and high resolution by the IUE, and nearly simultaneous optical and IR observations were obtained with ground-based telescopes. These data were used to produce a spectral energy distribution extending from 0.12 to 12.6 microns in order to investigate the conversion of UV to IR radiation in the circ…
The detection of a companion star to the Cepheid variable T Monocerotis
Doschek, G. A.; Mariska, J. T.; Feldman, U.
We have obtained ultraviolet spectra with the International Ultraviolet Explorer (IUE) spacecraft of the classical Cepheid T Mon at several phases in the 27 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less t…
IUE observations of the continuous spectrum of the Orion nebula.
Patriarchi, P.; Perinotto, M.
The continuous spectrum of the Orion Nebula has been observed in two positions in the bright Huyghenian region with the IUE (International Ultraviolet Explorer) satellite with a resolution of about 7 A in the spectral range of 1150-3200 A. The illuminating stars Theta 1 Orionis C and Theta 2 Orionis A have been observed under the same conditions. …