Search Publications
Identification of Lines in the Satellite Ultraviolet: The Spectrum of Tau Scorpii
Cowley, Charles R.; Merritt, Donald R.
The method of wavelength coincidence statistics (WCS) is applied to the ultraviolet spectra of Tau Sco obtained by the IUE. No identifications of elements heavier than Zn were made. With the exception of Zn IV, all identifications had been previously made in an exhaustive study of Copernicus spectra by Rogerson and Ewell (1985). A comparison of th…
Cosmic ray gradients in the outer Galaxy
Wolfendale, A. W.; Mayer, C. J.; Richardson, K. M. +2 more
The release of basic cosmic gamma ray data from the COS B satellite experiment has enabled a more detailed analysis than hitherto of the problem of variations of cosmic ray intensity locally and in the Outer Galaxy. It is found that there is still evidence for a modest cosmic ray gradient, particularly at the highest gamma ray energies where the p…
The MG II line profile in the Seyfert galaxy NGC 4151 : a new outflowing component.
Gull, T. R.; Penston, M. V.; Snijders, M. A. J. +1 more
This paper examines the Mg II λλ2795, 2802 doublet in the Seyfert galaxy NGC 4151 at a higher resolution than has previously been used, searching for velocity systems in absorption and emission. Evidence is presented for a new, narrow, outflowing absorption system in Mg II having a velocity of 825 km s-1 relative to the Sun, -165 km s
Determination of Photospheric Helium Abundances for the Hot White Dwarfs LB 1663 and CD -38 degrees 10980 from EXOSAT Soft X-Ray Photometry
Heise, J.; Kahn, S. M.; Paerels, F. B. S. +1 more
The photospheric soft X-ray emission of hot (Te> 20,000 K) DA white dwarfs is very sensitive to the composition of the stars' atmospheres. Very small amounts of helium in a hydrogen-dominated atmosphere, amounts which are difficult or impossible to measure at UV and optical wavelengths, can be detected in the soft X-ray band. In this…
Spectral variability of 4U 1145-619 during X-ray outburst.
Warwick, R. S.; Cook, M. C.
A series of observations of the X-ray pulsar 4U1145-619 were performed by EXOSAT during successive X-ray outbursts on this source in 1984 July and 1985 January. On all occasions the source exhibited a very hard power-law X-ray spectrum (photon spectral index ≡1.0) with a high-energy cut-off above ≡6 keV. The low-energy cut-off in the X-ray spectru…
IUE Observations of Hl-Canis and the Winds of Cataclysmic Variables
Raymond, J. C.; Mauche, C. W.
As evidenced by the P Cygni profiles of their ultraviolet resonance lines, cataclysmic variables—like early-type stars—are known to have extensive, high velocity winds. Assisted by AAVSO visual data andIUE ultraviolet spectra, we present an observational and theoretical study of the P Cygni profiles of the dwarf nova HL CMa. As these profiles are …
The X-Ray Orbital Lightcurve of AR Lac
Parmar, A. N.; White, N. E.; Culhane, J. L. +1 more
Using the EXOSAT observatory we have obtained the X-ray light curve of the 2 day eclipsing RS CVn binary system AR Lac continuously around one complete binary cycle. A deep minimum centered on primary eclipse is seen in the low energy telescope (0.05-2.0 keV), whereas the ME (1.0-10.0 keV) flux remained constant. This shows that the 5-7 million an…
Different regions of line formation in the envelope of the early emission line star HD 190073.
Ringuelet, A. E.; Rovira, M.; Cidale, L. +1 more
A description is presented of the spectral features that characterize the spectrum of HD 190073 both in the photographic region from about 3600 Å to about 6600 Å, and in the IUE ultraviolet, from about 1150 to about 3200 Å. A number of different types of profiles can be distinguished and this seems to imply that many different "broad" regions of l…
Analysis of the MG II resonance lines in the spectrum of Sirius.
Talavera, A.; Freire Ferrero, R.; Gouttebroze, P.
The atmospheric layers above the photosphere of Sirius A (Alpha CMa, AlV) are analyzed using high-resolution spectra of the Mg II resonance lines obtained with the Copernicus and IUE satellites. The line cores are formed at optical depths so small that an extension of the existing photospheric models for Sirius is necessary. Two tentative sets of …
Hot Wind in the Double Degenerate System Am-Canum
Kjeldseth-Moe, O.; Solheim, J. -E.
The close binary system Am CVn consists of two helium white dwarf stars in close orbit. Strong flickering in the optical light curve and the observed spin-up in the rotation period indicate that mass transfer takes place (Solheim et al., 1984). The optical spectrum shows broad helium absorption lines (Robinson and Faulkner, 1975) sometimes partly …