Search Publications
Lyman alpha fluxes of Seyfert galaxies and low-redshift quasars.
Gull, T. R.; Boggess, A.; Wu, C. -C.
The International Ultraviolet Explorer (IUE) was used to measure Ly-alpha fluxes for 13 type 1 Seyferts, one type 2 Seyfert, and one low-redshift quasar. The observed Ly-alpha/H-beta ratio is typically 5 for the type 1 Seyfert galaxies but is 20 for the single type 2 Seyfert. In the Ly-alpha/H-beta versus H-alpha/H-beta diagram, the observations d…
Outer atmospheres of cool stars. VI. Models for EPS ERI based on IUE spectra of C II, MG II, SI II, and SI III.
Linsky, J. L.; Simon, T.; Kelch, W. L.
Observations of the ultraviolet line spectrum of the active chromosphere star, Epsilon Eridani, obtained with the IUE satellite have been analyzed. The coupled statistical equilibrium and radiative transfer equations for the prominent transitions of C II, Mg II, Si II, and Si III. A satisfactory fit to all of the line strengths can be achieved wit…
Ultraviolet, X-ray, and infrared observations of HDE 226868 = Cygnus X-1.
Tanzi, E. G.; Tarenghi, M.; Chiappetti, L. +14 more
During April, May, and July of 1978, HDE 226868, the optical counterpart of Cygnus X-1, was repeatedly observed in the ultraviolet with the IUE satellite. Some X-ray and infrared observations have been made during the same period. The general shape of the spectrum is that expected from a late O supergiant. Strong absorption features are apparent i…
The ultraviolet spectrum of the T Tau star RW Aur.
Giampapa, M. S.; Imhoff, C. L.
Ultraviolet spectra of the T Tauri star RW Aurigae have been obtained with the International Ultraviolet Explorer. Emission lines include Mg II, Fe II, Cr II, Si I, Si II, Si III, Si IV, C II, C IV, and L alpha. The spectrum roughly resembles the solar chromospheric spectrum, but the surface fluxes are 200 times greater. N V and He II appear to be…
Ultraviolet, visible, infrared and X-ray observations of SCO X-1.
Davis, R. J.; Willis, A. J.; Wilson, R. +18 more
The first UV spectroscopic observations of the X-ray source Scorpius X-1, obtained with the IUE satellite, are presented. The UV data consist of low-resolution spectra in the 1150-3200 A wavelength range, and show emission lines arising in Si II and IV; C III and IV; N III, IV, and V; O IV and V, and He II. Also discussed are observations using vi…
Outer atmospheres of cool stars. III. IUE spectra and transition region models for alf CEN A and B.
Linsky, J. L.; Ayres, T. R.
We describe lUE ultraviolet spectra of two nearby dwarf stars, α Centauri A (G2 V) and B (K1 V). These data include high-resolution profiles of the Mg II h and k features and lower- resolution integrated fluxes of lines from the following species: H I, C I-IV, N V, O I, A1 II, Si II-IV, and Fe II. We find that surface fluxes in chromospheric and t…
Spatial imaging of hydrogen Lyman-alpha emission from Jupiter
Feldman, P. D.; Moos, H. W.; Weaver, H. A. +3 more
A sounding rocket measurement of the H I L-alpha emission from Jupiter made on Dec. 1, 1978 shows limb darkening and an average disk brightness of 13 kR. This brightness is significantly higher than in previous measurements, and was confirmed by an IUE observation on Dec. 10, 1978. Comparison with a plane-parallel hydrogen layer model indicates th…
Carbon in Comet Bradfield 1979l
Feldman, P. D.; A'Hearn, M. F.
Ultraviolet spectra of comet Bradfield obtained with IUE show a surprising absence of CO(+) despite the presence of CO2(+), and they also show, for the first time, the unambiguous presence of the Mulliken bands of C2. With the use of simultaneous ground-based data, a value of 0.00001 is derived for the transition moment of the a 3 Pi-X 1 Sigma g +…
Observations of the spectrum of Jupiter from 1500 to 2000 A with the IUE
Owen, T.; Caldwell, J.; Lane, A. L. +5 more
The paper examines the far-UV spectrum of Jupiter recorded by observations with the International Ultraviolet Explorer, noting that only the upper levels of the plant's atmosphere are sampled. It is shown that there are several absorptions caused by C2H2 and indications that NH3 may also be present at these altitudes. In addition, it is suggested …
Variable mass flux in the Be star 59 Cyg.
Doazan, V.; Thomas, R. N.; Kuhi, L. V.
The paper reports observations of 59 Cygni (B1.5 Ve) made in 1978 December with IUE at high resolution simultaneously with visual spectral observations. The C IV and probably the N V resonance absorption lines show whole-line violet displacements of 750 km/s, exceeding the photospheric escape velocity. Si IV and lesser ions show violet displacemen…