Search Publications
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…
Delta Andromedae (K3III) : an IRAS source with an unusual ultraviolet spectrum.
Judge, P. G.; Jordan, C.; Rowan-Robinson, M.
The IRAS survey has revealed anomalous cool infrared emission from a number of otherwise apparently normal K stars. IUE spectra of the brightest of these stars, Delta And, which is a spectroscopic binary and optical standard K3 III star, is obtained. The IUE spectra show the unexpected presence of C IV in emission, implying hot material (about 100…
Variable dust emission from Wolf-Rayet stars.
van der Hucht, K. A.; The, P. S.; Williams, P. M.
An infrared photometric survey of late type Wolf-Rayet stars shows little evidence for secular variation in mass loss or dust formation rates apart from the three known variables: WR 48a, WR 137 (HD 192641) and WR 140 (HD 193793, the prototype). In 1985, WR 140 again brightened sharply in the infrared owing to the formation of circumstellar dust. …
Ultraviolet spectrophotometry of comet Giacobini-Zinner during the ICE encounter
Feldman, P. D.; A'Hearn, M. F.; Schleicher, D. G. +8 more
A program of ultraviolet spectrophotometry using the International Ultraviolet Explorer (IUE) Observatory was carried out in support of the International Cometary Explorer (ICE) mission. The H 2O production rate was monitored from 1985 June to October. Between 1985 September 9 and 12, the spatial and temporal variation and abundance (or…
Chromospherically Active Stars. III. HD 26337 = EI Eri: an RS CVn Candidate for the Doppler-Imaging Technique
Fekel, Francis C.; Gillies, Kim; Quigley, Robert +1 more
The variable star HD 26337 = EI Eri is a chromospherically active G5 IV single-lined spectroscopic binary with a period of 1.94722 days. It has moderate strength Ca II H and K emission and strong ultraviolet emission features, while Hα is a weak absorption feature that is variable in strength. The inclination of the system is 46°±12°, and the unse…
Non-LTE abundance analysis of the early-type high galactic latitude star HD 100340.
Dufton, P. L.; Lennon, D. J.; Keenan, F. P. +2 more
Stellar equivalent widths and line profiles, measured from high resolution AAT and IUE spectra, are used in conjunction with non-LTE and LTE model atmosphere calculations to estimate the atmospheric parameters and chemical composition of the early-type high galactic latitude star HD 100340. The effective temperature (Teff= 25000K), surf…
The Ionization Structure of Planetary Nebulae. VII. New Observations of the Ring Nebula
Barker, Timothy
New optical spectrophotometric observations of emission-line intensities have been made in eight positions in the Ring Nebula corresponding to those observed previously with the Ultraviolet Explorer satellite; the total coverage is therefore 1400 to 7200 A. The intensities are in generally good agreement with those found previously in correspondin…
Non-radial pulsations in the extreme helium star HD 160641.
Jeffery, C. S.; Kilkenny, D.; Lynas-Gray, A. E. +1 more
Mean periods of 0.35±0.01, 0.71±0.05, 1.12±0.13 and 1.77±0.34 day are identified from separately analysed photometric observations (obtained in 1979 and 1982) of the extreme helium star HD 160641. Radial velocities were obtained simultaneously with photometry on three nights in 1982. Optical variations are not accompanied by detectable colour chan…
Ultraviolet and Visual Spectroscopy of DB White Dwarfs
Nelan, E. P.; Wegner, G.
Visual wavelength and IUE ultraviolet spectroscopy and model atmospheres of DB white dwarfs are reported. A search for spectral lines due to elements other than helium, and in particular carbon and hydrogen, was made. In no case is there a positive detection of carbon from these data, and upper limits relative to helium by number are derived in th…
The variation of protons, alpha particles, and the magnetic field across the bow shock of comet Halley
Schwenn, R.; Balsiger, H.; Neubauer, F. M. +7 more
Data from the Ion Mass Spectrometer and the magnetometer on the Giotto spacecraft are used to examine the structure of the inbound crossing of the comet Halley bow shock on March 13, 1986. It is found that the velocity decrease, the field strength increase, and the heating of picked up cometary protons occurred over a broad region corresponding to…