Search Publications
The D/h Ratio in Water from Comet p/ Halley
Berthelier, J. J.; Eberhardt, P.; Krankowsky, D. +6 more
The neutral gas mass spectrometer on the Giotto spacecraft made neutral and ion composition measurements with a high mass resolution. From a preliminary evaluation of the ion data within the contact surface the authors obtain for the water in Halley an 18O abundance of 18O/16O = 0.0023±0.0006 and for the D/H ratio …
Rotational modulation and flares on RS CVn and BY DRA stars. VI. Physical parameters of the chromospheres/transition regions of V711 Tau (HR 1099), II Peg and AR Lac during october 1981.
Doyle, J. G.; Linsky, J. L.; Rodono, M. +2 more
Ground-based optical and IUE satellite-ultraviolet observations of three RS CVn stars are combined with density sensitive line ratios and differential emission measure curves to describe the physical conditions in their outer atmospheres. Solar-like densities are found to be representative of average conditions on two of the stars, V 711 Tau and A…
General Features of Comet p/ Halley - Solar Wind Interaction from Plasma Measurements
Anderson, K. A.; Reme, H.; Korth, A. +8 more
The Giotto RPA-COPERNIC plasma experiment identified several regions in which the solar wind interaction with the cometary plasma displayed characteristic features: (1) Beginning ∼4.6×106km from the comet there is an upstream region with sporadic connection to the comet, (2) An electron foreshock is present up to 2.5×105km aw…
Ion Temperature and Flow Profiles in Comet p/ Halley's Close Environment
Schwenn, R.; Balsiger, H.; Goldstein, R. +5 more
The HIS instrument of the ion mass spectrometer on board the Giotto spacecraft identified the contact surface at 4800 km distance from the comet nucleus. This boundary is clearly seen by a drastic drop in the temperatures of different ion species from about 2000 K outside to values as low as 300 K inside. Also, inside the contact surface an outflo…
High-energy gamma-ray and hard X-ray observations of CYG X-3.
Strong, A. W.; Hermsen, W.; Pollock, A. M. T. +7 more
High-energy (70 MeV < E < 5 GeV) gamma-ray observations of Cyg X-3 by the ESA satellite COS-B and hard X-ray (14 keV < E < 140 keV) observations by the Leiden-MIT balloon experiment, Leimit, are presented. A comparison with, and a study of earlier results over the 14 decades in energy from 1 keV up to ≡1017eV indicates that …
Star formation in nuclei of SO/E galaxies.
Rocca-Volmerange, B.; Guiderdoni, B.
Spectra of nuclei for some lenticular and elliptical galaxies observed from the IUE satellite in the far-UV light are analyzed with the help of the IUE spectral atlases using an almost similar resolution for galaxies and stars, down to about 8A for a significant signal/noise ratio. In the 2500A-3150A wavelength range, all gas-poor galaxies show 'r…
Magnetic structure in cool stars. XIII - Appropriate units for the rotation-activity relation
Rutten, R. G. M.; Schrijver, C. J.
The paper compares relations between coronal and chromospheric emissions, and between activity and stellar rotation, in which the radiative emissions that measure the magnetic activity of cool stars are expressed in different units. The surface flux density appears to be the most suitable unit in which to express the radiative emission measuring s…
Photometric properties of SN 1987A and other sources in the same field.
Panagia, N.; Clavel, J.; Wamsteker, W. +5 more
The authors find that the UV flux of SN 1987A declines since the very first IUE observation at a rate which is faster at shorter wavelengths while the emission around 5100 Å increases slowly but steadily with time. Thus, the UV radiation dominates the overall emission at early phases but becomes completely negligible at later phases. Such an evolu…
EUV photometry of DA white dwarfs with EXOSAT.
Jordan, S.; Koester, D.; Brunner, H. +1 more
The authors present EXOSAT EUV observations for 9 white dwarfs of spectral type DA. These are analysed together with other observational data from the literature using theoretical model atmospheres. For 8 objects He/H abundance ratios and interstellar hydrogen column densities are obtained. The data for HZ 43 seem to contradict recent results of o…
Photometry and spectroscopy of the O-type variable HD 167971.
Stahl, O.; Leitherer, C.; Zickgraf, F. -J. +9 more
The authors present photometric and spectroscopic observations of the O-type variable HD 167971. From a period analysis of the visual light-curve they find P = 3.3213 days. Combining the photometric and spectroscopic data they derive a consistent model for the system which can be understood in terms of a close O-type eclipsing binary and a third, …