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The ISOPHOT far-infrared serendipity north ecliptic pole minisurvey
Kessler, M. F.; Burgdorf, M.; Lemke, D. +11 more
The ISOPHOT Serendipity Survey fills the otherwise unused slew time between ISO's fine pointings with measurements in an unexplored wavelength regime near 200 microns. In order to test point source extraction software, the completeness of the detected objects as well as the astrophysical content we investigate a 100 sq degr field near the North ec…
Photospheric metals in hot DA white dwarfs
Dreizler, S.; Wolff, B.; Koester, D. +1 more
Previous observations of the soft X-ray and EUV region with the Einstein, EXOSAT, and ROSAT satellites have indicated the presence of photospheric absorbers in most DA white dwarfs with {T_eff} ga 40000K. Several of these objects have now been observed with the Extreme Ultraviolet Explorer (EUVE). Since the detection of individual metal lines is r…
Global warming on Triton
Olkin, C. B.; Franz, O. G.; Buie, M. W. +11 more
Triton, Neptune's largest moon, has been predicted to undergo significant seasonal changes that would reveal themselves as changes in its mean frost temperature. But whether this temperature should at the present time be increasing, decreasing or constant depends on a number of parameters (such as the thermal properties of the surface, and frost m…
Molecular gas phase counterparts to solid state grain mantles features: implication for gas/grain chemistry
Boulanger, F.; Puget, J. -L.; Dartois, E. +4 more
We present ISO SWS (AOT6) observations of the protostellar object RAFGL 7009S. This source is particularly interesting for the characterisation of chemistry arising from grain surfaces and mantles, since the solid state features of many simple molecules such as H_2O, CO, CO_2, (13) CO_2 and CH_4 are detected, together with weaker features not yet …
The comptonized X-ray source X 1724-308 in the globular cluster Terzan 2
Stella, L.; Parmar, A. N.; Guainazzi, M. +3 more
We report on the BeppoSAX observation of the X-ray source X 1724-308 in the globular cluster Terzan 2. The broadband spectrum can be described as the superposition of a power-law with photon spectral index Gamma =~ 1.6-1.9 and a thermal component with typical temperature kT ~ 1 keV. X 1724-308 is detected in the PDS up to 150 keV with a S/N ratio …
The blue-bump of 3C 273
Paltani, S.; Walter, R.; Courvoisier, T. J. -L.
We present optical and ultraviolet observations of 3C 273 covering the whole life of the IUE satellite. We analyze the variability properties of the light curves, and find that two variable components, written V_\nuAA\ and S_\nuBB\ respectively, must contribute to the S_\nuB\ emission in this object. The V_\nuAA\ component produces most of the var…
Spectral analysis of O(He)-type post-AGB stars
Rauch, T.; Dreizler, S.; Wolff, B.
We present an analysis of two recently discovered, very hot hydrogen-deficient post-AGB stars of spectral type O(He), namely HS 1522+6615 and HS 2209+8229, by means of state-of-the-art NLTE model atmospheres based on new optical, UV, and X-ray observations. In the spectra of HS 1522+6615 we discovered a variability of the \Ionw{O}{6}{5290} line co…
High-Frequency Peaks in the Power Spectrum of Solar Velocity Observations from the GOLF Experiment
García, R. A.; Pallé, P. L.; Turck-Chièze, S. +9 more
The power spectrum of more than 630 days of full-disk solar velocity data, provided by the GOLF spectrophotometer aboard the Solar and Heliospheric Observatory, has revealed the presence of modelike structure well beyond the acoustic cutoff frequency for the solar atmosphere (νac~5.4 mHz). Similar data produced by full-disk instruments …
Modeling of 3-D Corotating Cosmic-Ray Structures in the Heliosphere
Jokipii, J. R.; Kóta, J.
We present a brief review of the modeling of corotating 3-dimensional features in heliospheric cosmic rays. The model heliosphere incorporates a wavy current sheet and Corotating Interaction Regions (CIRs). We find that present models can qualitatively account for the observed extension of recurrent 26-day cosmic-ray variations to high heliospheri…
Nuclear stellar discs in early-type galaxies - I. HST and WHT observations
van den Bosch, Frank C.; van der Marel, Roeland P.; Jaffe, Walter
We present multi-colour (U, V and I) photometry obtained with the second Wide Field and Planetary Camera (WFPC2) on the Hubble Space Telescope (HST), and spectra taken with the William Herschel Telescope (WHT) and the HST Faint Object Spectrograph (FOS), for the early-type galaxies NGC 4342 and 4570. These galaxies are intermediate between ellipti…