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Activity of comet P/Halley 23-25 March, 1986 - IUE observations
Feldman, P. D.; A'Hearn, M. F.; McFadden, L. A. +3 more
A large but gradual increase in the brightness of the emission bands of comet Halley and, thus, in the coma abundance of OH, CS, CO2(+), and dust was observed with the International Ultraviolet Explorer (IUE) satellite from Mar. 23 to 25, 1986. This brightness change was also monitored by the Fine Error Sensor (FES) tracking and acquisition camera…
A study of the massive O-type binary IOTA Orionis.
Howarth, I. D.; Stickland, D. J.; Lloyd, C. +1 more
Iota Orionis is an O9 III+B1 III binary with a highly eccentric orbit. Using coudé spectra the authors have updated its ephemeris and established a value for the apsidal motion. Combining the orbital elements, the astrophysical data (the primary is an O9 III standard star in the Orion Association), and photometry through a grazing eclipse, they ha…
Charge Exchange of Solar Wind Ions in the Coma of Comet p/ Halley
Balsiger, H.; Geiss, J.; Goldstein, B. E. +7 more
In addition to solar wind pick-up of cometary ions, charge exchange between solar wind ions and cometary neutrals is, potentially, an important comet-solar wind interaction closer to the nucleus. One monitor of the charge exchange rate is the relative abundances of solar wind He2+ and He+. Radial profiles of these two ions me…
Silicon absorption in UV spectra of AP SI stars.
Lanz, T.; Artru, M. -C.
The authors investigate the role of silicon UV absorption occurring in the atmosphere of early-type stars. A detailed analysis of the λλ1250 - 1850 Å range is presented. High-resolution spectra are obtained from the IUE database for typical silicon stars and for a few normal main-sequence stars. The strongest absorption in these spectra are the re…
An Interpretation of the Ion Pile-Up Region Outside the Ionospheric Contact Surface
Schwenn, R.; Balsiger, H.; Ip, W. H. +3 more
An analysis interrelating some of the results of plasma measurements by the Giotto spacecraft in the inner coma of comet P/Halley suggests that the formation of the plasma pile-up region at a distance of 10,000 km - 30,000 km may be the result of accumulation of ion density in a stagnant flow region with a sharp electron temperature transition for…
The peculiar early-type emission line supergiant S18/SMC : an opticaland ultraviolet study.
Shore, S. N.; Allen, D. A.; Sanduleak, N.
The authors have observed the extreme early-type emission line star S18/SMC during 1978 to 1983 with both optical and ultraviolet low and moderate dispersion spectra. The star is a pronounced variable in He II, C IV, N IV, N V and Si IV. There appear to be no associated photometric variations from λλ1200 to 10,000 Å. A model is presented for the e…
Early observations of Supernova 1987A with the International Ultraviolet Explorer (IUE).
Panagia, N.; Talavera, A.; Clavel, J. +7 more
Early phase observations of the SN 1987A in the ultraviolet wavelength range are presented. Some general considerations on the behaviour of this supernova are given. Also, a comparison is made with other supernovae observed in the ultraviolet with the IUE Observatory.
EXO 023432-5232.3 : a new 114-minute probable AM Herculis-type binary.
Tagliaferri, G.; Beuermann, K.; Giommi, P. +1 more
A new probable AM Herculis binary was found in the course of an optical identification program of serendipitous X-ray sources detected with the EXOSAT satellite. Spectrophotometry of the 19 mag optical counterpart shows that it carries most of the hallmarks of AM Herculis binaries. The orbital period is 114.6 minutes and makes it the sixth AM Her …
Description of the Main Boundaries Seen by the Giotto Electron Experiment Inside Comet p/ Halley - Solar Wind Interaction Region
Anderson, K. A.; Reme, H.; Korth, A. +8 more
The Giotto electron-plasma experiment identified several boundaries inside the comet Halley-solar wind region. Two of them are particularly interesting; they separate very different plasma regimes on quite sharp length scales and furthermore their existence was not foreseen in theoretical models. They are the limit between the transition region an…
The composition and radial dependence of cometary ions in the coma of comet P/Halley
Anderson, K. A.; Korth, A.; Carlson, C. W. +2 more
The heavy ion analyzer, RPA2-PICCA, on board the Giotto spacecraft detected an increase in the densities of cometary ions within a cometocentric distance of 150,000 km. The composition of cometary ions changed dramatically as the comet's nucleus was approached, but it was clearly dominated by the water group. The second and third most abundant ion…