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Long-term stability of the Io high-temperature plasma torus
Skinner, T. E.; Durrance, S. T.; Feldman, P. D. +3 more
The IUE satellite was used to monitor the UV line emission of S+, S++ and S+++ ions in the high-temperature portion of the Io plasma torus. Thirteen observations obtained over a 5 yr period from 1979 March to 1984 March show that the plasma parameters of the high-temperature portion of the torus have surprisingly s…
Observational studies of the symbiotic stars. III. High-dispersion IUE and H alpha observations of EG Andromedae.
Stencel, R. E.; Anderson, C. M.; Slovak, M. H. +1 more
High-dispersion IUE and optical spectra are presented for the symbiotic star EG Andromedae (HD 4174). Remarkable emission-line strength and profile variations are confirmed for the S IV, O IV, C IV, and He II ultraviolet lines as well as H-alpha. Accurate cross-correlation absorption-line velocities determined from Ti I, Ca I, and Fe I features co…
The ionization structure of planetary nebulae. V. NGC 3242.
Barker, T.
Spectrophotometric observations of emission line intensities over the spectral range 1400 A to 9600 A were made in five positions in the planetary nebula NGC 3242. In two of the positions, both the weakness of the 1548 A, 1550 A C IV resonance lines and the steepness of the Balmer decrement suggest the possibility of internal dust in the nebula. T…
M 4-18 : a young cool planetary nebula.
Goodrich, R. W.; Dahari, O.
The unresolved planetary nebula M4-18 has been studied spectroscopically from the ultraviolet to the near-infrared. The nebula is found to be of very low excitation, with electron density Ne = 11,000 + or - 1,000/cu cm and electron temperature Te = 5600 + or - 1300 K, and a high O abundance. The central star is found to be among the coolest centra…
Simultaneous observations of CA II K and MG II K in T TAuri stars.
Basri, G.; Calvet, N.; Giampapa, M. S. +1 more
The first simultaneous, calibrated observations of the Ca II K and Mg II k resonance lines in T Tauri stars are presented. It is found that for T Tauri stars with mass greater than 1.5 solar mass, which have radiative cores and tend to be fast rotators, the k line seems to arise in an extended region (probably also responsible for the H-alpha emis…
An analysis of the bright white dwarf CD -38 10980.
Bruhweiler, F. C.; Wesemael, F.; Holberg, J. B. +1 more
The bright DA white dwarf CD - 38 deg 10980 is comprehensively analyzed using all available data. Detailed comparisons of the overall energy distribution and Lyman-alpha and Balmer profiles are made with theoretical predictions based on a homogeneous grid of model atmospheres. These comparisons yield a consistent, well-defined effective temperatur…
Spectrum of the high-excitation planetary nebula NGC 6741 (33-2 1).
Czyzak, S. J.; Keyes, C. D.; Aller, L. H.
Image tube observations carried out at the Lick and Mount Wilson Observatories were combined with IUE and infrared observations to study the spectra of the high-excitation planetary nebula NGC 6741. Plasma diagnostics were carried out and ion concentrations were calculated for ions from He I to Ca4(+). The ion densities and plasma diagnostics data…
The ultraviolet variability of Seyfert 1 galaxies.
Huchra, J. P.; Geller, M. J.; Chapman, G. N. F.
Multiple IUE spectra of nine Seyfert 1 galaxies, obtained over four years, were examined. Spectra of Mrk 509, ESO 141-G55, Fairall 9, III Zwicky 2, Mrk 279, NGC 3783, NGC 4593, NGC 7213, and NGC 7469 were examined for evidence of variability in both continuum and emission-line fluxes. All except NGC 7213 and III Zw 2 show 20 percent-80 percent con…
AY Ceti : a flaring, spotted star with a hot companion.
Simon, T.; Gibson, D. M.; Fekel, F. C., Jr.
AY Ceti is a late-type single-line spectroscopic binary, a bright X-ray source (L/x/ equal to about 1.5 x 10 to the 31st ergs/s), and a spotted star, as evidenced by its prominent photometric wave. In this paper, observations made with the IUE satellite and the VLA radio interferometer are reported. The 1200-2000 A UV spectrum of AY Cet shows a ho…
Observations of the low-redshift broad absorption line QSO PG 1700+518 : limits on the fraction of QSOs with broad absorption lines at low redshift and the physical conditions in the broad absorption line region.
Peterson, B. M.; McMahon, R. G.; Weymann, R. J. +3 more
The authors present IUE and optical observations demonstrating that the zem = 0.29 QSO PG 1700+518 is a broad absorption line (BAL) QSO. This object is unique because of its low redshift and because it is one of only two BAL QSOs which exhibit moderate strength Mg II BALs. The discovery suggests that the fraction of QSOs with BALs at lo…