Search Publications
Extinction of NGC 7027.
Seaton, M. J.
Emission intensities of recombination lines in hydrogenic spectra are known accurately relative to intensities in the free-free radio continuum. For NGC 7027 intensities have been measured for the radio continuum and for H I and He II lines in the wavelength range from 2.17 microns to 1640 A; comparison with the calculated emission intensities giv…
Observations of 3C 390.3 with the International Ultraviolet Explorer.
Perryman, M. A. C.; Ferland, G. J.; Longair, M. S. +1 more
Observations of the radio galaxy 3C 390.3 made with IUE are presented; these allow separate determinations of the Lyman/Balmer ratios in both the narrow and broad emission-line regions. The broad-line L-alpha/H-alpha ratio confirms the anomalous results found previously in quasars; in this case a ratio is found about 15 times smaller than that pre…
Oxygen VI in stellar winds.
Morton, D. C.
A review of observational evidence for five-times ionized oxygen (OVI) in stars and new high-resolution spectral scans obtained with Copernicus satellite are presented to show how this phenomenon varies with spectral type. The region of the OVI resonance doublet was observed in nine stars with the Copernicus spectrometer, and P Cygni profiles or s…
Ultraviolet and X-ray observations of the BL Lac object MK 501.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +3 more
We present ultraviolet and X-ray satellite observations of Mk 501. The ultraviolet data after dereddening assuming E(B-V) = 0.11 show a power-law spectrum with α = 0.51+0.10-0.15. The visible and infrared fluxes are in good agreement with this power-law if the underlying elliptical galaxy has a luminosity MV = -22.…
Far ultraviolet line profiles in the Seyfert galaxy NGC 4151.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +2 more
Two high-resolution far-UV spectra (1150-2000 A) of the Seyfert 1 galaxy NGC 4151 are presented which were obtained from the IUE satellite with a resolution of about 10,000. It is found that the Ly-alpha line in NGC 4151 is asymmetric and rather narrow, that the Ly-alpha/H-beta ratio varies across the line, and that there are two absorption system…
The [Ne IV] 2D -> 4S lines in the planetary nebula NGC 7662.
Lutz, J. H.; Seaton, M. J.
Results are reported for high-resolution IUE satellite observations of the 2p 3 2D 3/2 - 4S, 2D 5/2 - 4S UV forbidden lines of Ne IV in the spectrum of NGC 7662. Precision measurements of the wavelengths are obtained, along with an improved determination of Ne IV doublet-quartet separations, a measurement of the intensity ratio for the forbidden N…