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Properties of mass-loading shocks 2. Magnetohydrodynamics
Neubauer, F. M.; Zank, G. P.; Oughton, S. +1 more
The one-dimensional magnetohydrodynamics of shocked flows subjected to significant mass loading are considered. Recent observations at comets Giacobini-Zinner and Halley suggest that simple nonreacting MHD is an inappropriate description for active cometary bow shocks. The thickness of the observed cometary shock implies that mass loading represen…
Spectroscopic study of the atmospheric eclipsing binary VV Cephei.
Hack, M.; Boehm, C.; Engin, S. +3 more
We present the results of the study of 49 high dispersion spectrograms obtained at the Haute-Provence Observatory from July 1967 to January 1981, including the epoch of the eclipse of 1977. The radial velocity, intensity and profile variations of several absorption and emission lines are given. The ratio between the fluxes of the M2 giant and the …
Luminous Blue Variables; Quiescent and Eruptive States.
Wolf, B.
Extensive X-ray monitoring of the broad-line radio galaxy 3C 382.
Giommi, P.; Barr, P.
The results of an intensive monitoring campaign of the X-ray light curve of the broad- line radio galaxy 3C 382, performed using the EXOSAT observatory over a five-month period in summer 1985, are presented. Significant variations on a time-scale of several days are found in both the hard and soft X-ray bands, probably superimposed on a systematic…
Inner coma imaging of Comet Levy (1990c) with the Hubble space telescope
Feldman, P. D.; A'Hearn, M. F.; Weaver, H. A. +5 more
Comet Levy (1990c) was observed with the Hubble Space Telescope (HST) on UT 27 September 1990 when both the heliocentric and geocentric distances were ∼1 AU. Two sets of images of the comet were taken 6.5 hr apart with the Wide-Field Camera (WFC) through a broadband red filter that was selected to isolate continuum emission peaking sharply at the …
TYCHO photometry calibration and first results
Snijders, M. A. J.; Grewing, M.; Lindegren, L. +6 more
A description of the data reduction methods used for the Tycho photometry and the software package to implement these methods is presented. Results derived from a preliminary reduction of eight weeks of data employing these methods are reported. A critical discussion of the sources of photometric errors and the expected and achieved photometric ac…
EXOSAT Observations of the X-Ray Binary Pulsar 4U 1538-52
Cusumano, G.; Frontera, F.; Orlandini, M. +2 more
Results are reported from a temporal and spectral analysis performed on four EXOSAT observations, part of which were taken from the EXOSAT archive, carried out during March and August 1984. In the first observation an absorbing episode was detected, which may be attributed to an inhomogeneity in the stellar wind of QV Nor; the scale height of this…
Ionizing radiation in the variable active galaxy 3C 120.
Gondhalekar, P. M.
The change in the C IV/Lyα line ratio when the continuum intensity changes, in the spectrum of the radio-loud active galaxy 3C 120, has been modelled. This analysis defines (i) the average parameters of the broad- line region in this galaxy and (ii) the ionizing spectrum seen by the clouds in this region. A soft extreme-ultraviolet continuum is re…
Early improvements to the HIPPARCOS Input Catalogue through the accumulation of data from the satellite - Including the NDAC attitude reconstruction description
van Leeuwen, Floor; Lindegren, Lennart; Penston, Margaret J. +2 more
A description of ways in which the Northern Data Analysis Consortium (NDAC) accumulates positional and photometric data as obtained in the early stages of the reduction of data from the Hipparcos instrument is presented. An outline of the closely associated attitude reconstruction process is also given. Positional internal accuracies in arcsec, an…
The Ulysses Mission: In-ecliptic phase
Smith, E. J.; Wenzel, K. -P.
The Ulysses mission is unique in the history of the exploration of our solar system by spacecraft. The path followed by Ulysses will enable us, for the first time, to explore the heliosphere within a few astronomical units of the Sun over the full range of heliographic latitudes. The mission, a collaboration between ESA and NASA, was launched on 6…