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Discovery Of Mg-Rich Pyroxenes In Comet C/1995 O1 (Hale-Bopp): Pristine Grains Revealed At Perihelion
Woodward, Charles E.; Koike, Chiyoe; Wooden, Diane H. +2 more
The NASA Ames HIFOGS spectrometer observed comet C/1995 O1 (Hale-Bopp) at epochs including 96 Oct 7–14 UT (2.8 AU), 97 Feb 14–15 UT (1.2 AU), 97 Apr 11 UT (0.93 AU), and 97 Jun 22, 25 UT (1.7 AU). The HIFOGS 7.5–13.5 µm spectrophotometry (R = 360 - 180) of the silicate feature at 2.8 AU is identical in shape to the ISO SWS spectra of comet H…
Evidence for Absorption in NGC 1068
Boksenberg, A.; Catchpole, R. M.
We present evidence that interstellar absorption is responsible for producing much of the complex morphology seen in the inner few arcseconds of NGC 1068.
Absolute stellar proper motions with reference to galaxies of the M81 group
Meusinger, H.; Brosche, P.; Odenkirchen, M. +2 more
We report on the measurement of absolute proper motions of stars of magnitude 7 to 14.5 in a 2 deg X 2 deg field in the region of the M81 group of galaxies. This work is part of the Bonn program for the extragalactic link of Hipparcos. The proper motions were determined from a collection of photographic plates covering the time interval from 1894 …
HST WFPC2 Line and Continuum Images of NGC 1068
Ford, H. C.; Kriss, G. A.; Tsvetanov, Z. I. +1 more
Ultraviolet Ionization Stratification in Wolf-Rayet Winds
Rochowicz, Krzysztof
Ionization stratification can be used to study the structure of WR winds. In an accelerated outflow the stratification is observable through the Doppler effect as an inverse correlation of ionization potential (IP) with line width (FWHM). However, not only the average line widths of different ions, but also the line widths of one series of HeII sh…
Separation rate of the magnetic field lines observed by ULYSSES at high latitude
Balogh, A.; Erdös, G.; Kóta, J.
Ulysses has observed enhanced magnetic field fluctuations embedded in the fast solar wind originating from the high latitude coronal hole. These fluctuations proved to affect charged particle transport significantly. In this paper we apply a new method to determine the magnetic field line mixing from the actually measured magnetic field.
Ly alpha Constraints on the Nature of the X-Ray--absorbing Medium in Cooling Flow Clusters
Laor, Ari
X-ray spectra of a significant fraction of cooling flow (CF) clusters of galaxies indicate the presence of large columns of ``cold'' absorbing material. The physical nature of the absorbing medium remains a mystery. Searches for H I in this medium using the 21 cm hyperfine structure line yielded null results in most cases. The Lyα absorption cross…
Elemental abundances in the Hg-Mn star γ Corvi.
Houziaux, L.; Fremat, Y.
Spectral data obtained at ESO, Observatoire de Haute-Provence and with the IUE covering the 120-910nm spectral range allowed us to determine the abundances of 21 elements in the atmosphere of the moderately fast rotating Hg-Mn star γ Corvi. We find that helium, carbon, nitrogen, magnesium, aluminium, silicium, sulfur, chromium, iron and nickel are…
M VIII Diagnostic Line Ratios in SKYLAB Solar Observations
Doyle, J. G.; Keenan, F. P.; Widing, K. G. +4 more
Recent calculations of Mgviii electron and proton impact excitations rates are used to derive theoretical electron temperature (Te)- and density (Ne)-sensitive emission line ratios involving transitions in the 315-782 Å wavelength range. Some of these ratios are presented in the form of ratio-ratio diagrams, which should in p…
Using the Earth orientation parameters to link the HIPPARCOS and VLBI reference frames.
Pesek, I.; Vondrak, J.; Ron, C.
One of the methods, used to link the free Hipparcos reference system to the conventional extragalactic reference system, is the indirect method using the rapidly rotating terrestrial reference system as an intermediary. We solve the Earth orientation parameters, referred to the preliminary Hipparcos reference frame H37C, from the observations made…