Search Publications
Camera Artifacts in IUE Low-Dispersion Spectra
Crenshaw, D. Michael; Norman, Dara J.; Bruegman, Otto W.
Sky-background images obtained by the International Ultraviolet Explorer (IUE) were analyzed to study artificial spectral features (camera artifacts) in low-dispersion spectra. The artifacts mimic emission features and have been present in long-exposure spectra since the launch of the IUE satellite. The camera artifacts are strong in spectra chara…
The ephemeris of X 1822-371.
Hellier, Coel; Mason, Keith O.; Smale, Alan P. +1 more
From the analysis of eclipses observed with the HEAO-1, Einstein, Exosat and Ginga satellites, it is shown that the orbital period of X1822 - 371 is increasing on a time-scale of 2.9 million yr. The period change, one of only three determined amongst the LMXBs, is in the opposite sense to the expected evolutionary trend, but in the same sense as t…
Chromospheres of Metal-deficient Field Giants
Smith, Graeme H.; Dupree, A. K.; Hartmann, L.
Observations of the 2800-A Mg II line have been obtained with IUE for a sample of 10 metal-deficient field giant stars to search for chromospheric emission and signatures of mass loss, as well as to establish the level of chromospheric radiative energy losses from these stars. Mg II emission is probably present in all stars. High-resolution spectr…
Spectral Synthesis in the Ultraviolet. III. The Spectral Morphology of Normal Stars in the Mid-Ultraviolet
O'Connell, Robert W.; Burstein, David; Wu, Chi-Chao +1 more
The morphology of 218 mid-UV spectra of stars ranging from O through K in spectral type is examined. Several new line and continuum indices are defined and their usefulness as temperature, luminosity, and metallicity discriminants is discussed. Mid-UV stellar continua are found to be markedly affected by abundance. A UV excess, delta(2600-V), is c…
Bulk properties and velocity distributions of water group ions at comet Halley: Giotto measurements.
Coates, A. J.; Glassmeier, K. -H.; Wilken, B. +3 more
In the region upstream of comet Halley, pickup heavy ions of cometary origin were directly observed by the Implanted Ion Spectrometer on Giotto. Here the authors discuss diffusion of this population in pitch angle and in energy, during the approach to the comet and on the outbound leg. The two data sets are compared and qualitative ideas on scatte…
The IRAS Low-Resolution Spectra of Planetary Nebulae
Volk, Kevin; Cohen, Martin
This paper presents the low-resolution spectra of 170 planetary nebulae observed by IRAS, most of which were not included in the Atlas of Low-Resolution Spectra. These have been classified into eight groups based upon the spectral morphology, with emphasis on the dust continuum rather than the spectral lines. The Low-Resolution Spectrometer (LRS) …
HM Sagittae : the evolution of a symbiotic nova.
Vogel, M.; Nussbaumer, H.
HM Sge was discovered in 1975, when it became a symbiotic nova. HM Sge is still evolving. Since its discovery, significant spectral changes have taken place in the ultraviolet, the radio, as well as in the visual wavelength ranges. Here, IUE observations from 1982 to 1989 are reported. The implications of the available spectral information since t…
Observations of the new luminous blue variable R 110 of the Large Magellanic Cloud during an F star-phase.
Stahl, O.; Wolf, B.; Cassatella, A. +2 more
The LMC star R 110 has increased its visual brightness by about 0.5 mag in the last ten years. During its brightest observed phase in January and February 1989, we obtained UBVRI and JHK photometry, low dispersion spectroscopy with IUE, and high dispersion spectroscopy in the optical with CASPEC and in the satellite UV with IUE. During the brighte…
MG II Observed in the Local Interstellar Medium: The Local Cloud
Molaro, P.; Beckman, J. E.; Vladilo, G. +1 more
Observations of interstellar absorptions superposed on the chromospheric Mg II emissions of nearby cool stars have been used to explore the structure of the local interstellar medium along many lines of sight. The interstellar cloud in which the sun is immersed (the 'local cloud', hereafter LC) has not previously been detected using this technique…
Localization of one of the galactic centre X-ray burst sources.
Skinner, G. K.; Eyles, C. J.; Foster, A. J. +1 more
Observations of an X-ray burst which occurred during the Spacelab-2 observations of the Galactic Center region are reported, and it is shown that it originated in the more southerly component of a previously reported persistent X-ray object, now resolved into two sources separated by 3 arcmin. Present knowledge of the number and location of the Ga…