Search Publications
A simultaneous X-ray and radio observation of a flare from Algol
Parmar, A. N.; White, N. E.; Culhane, J. L. +1 more
An X-ray flare was observed from Algol using the low and medium energy detectors on the European Space Agency's EXOSAT observatory. Spectra obtained during the flare are well fitted by thermal continua while an Fe XXV emission feature was also detected. The strength of this feature indicates a cosmic abundance for iron. The data indicate that the …
Soft X-ray characteristics of white dwarfs observed by EXOSAT
Grewing, M.; Heise, J.; Bleeker, J. A. M. +5 more
EXOSAT has observed 19 hot white dwarfs with alleged strong soft X-ray emission. Positive detection of a large fraction of this sample was obtained, among these practically all hot DA dwarfs. High-resolution spectral data, acquired with the 500 1/mm grating spectrometer, indicates no traces of He in the atmosphere of HZ43, i.e. n(He)/n(H) <= 10…
The soft X-ray superoutburst of VW hydri: 14 second periodicity
Heise, J.; van der Woerd, H.; Paerels, F.
EXOSAT observations of the dwarf nova VW Hydri reveal a strong soft X-ray flux during optical superoutburst. The onset of the X-ray outburst was delayed by 2.5 days compared to the optical outburst. A modulation of the extreme soft X-ray flux was detected, consistent with a coherent (0 >x 107) pulsation with a period of 14.07 seconds…
Optical and X-ray observations of 4U2129+47/V1727 CYG in a quiescent state
Pietsch, W.; Gottwald, M.; Steinle, H.
We observed the 5.2 h X-ray binary 4U2129+47 for more than one orbital cycle on 29 September and 4 October 1983 using the LE, ME and GSPC detectors of the ESA X-ray satellite EXOSAT. In neither detector an X-ray flux from the source could be detected. Quasi-simultaneous UBV observations using the 2.2 m telescop at the German-Spanish Astronomical C…
Photometric calibration and first results obtained with the UFT experiment on board the astron satellite
Petrov, P.; Hua, C. T.; Courtes, G. +7 more
The UV telescope of 30 cm diameter equipped with a three channel scanner spectrometer aboard the highly eccentric orbit space station ``ASTRON'' is described
Absolute calibration of the whole device is performed using spectra of standard stars, of which absolute values were obtained by TDI or IUE experiments. Several photometric controls have…Einstein and EXOSAT observations of geminga (1E0630+178). A summary of the short - and medium - term variability data
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +1 more
The X-ray source 1E 0630 + 178 was discovered by Bignami et al. (1983) during an X-ray survey. The survey was conducted with the aid of the Einstein Observatory. The involved field was also observed with the Exosat satellite in September 1983, when both Low Energy telescopes were still operating. The Einstein and Exosat data bases were utilized in…
A search for X-ray emitting coronal structures in algol
Parmar, A. N.; White, N. E.; Culhane, J. L. +3 more
Algol was observed with the low energy imaging X-ray telescope and the medium energy detectors on the ESA EKOSAT spacecraft during the time of secondary optical eclipse when the B star passes in front of its K type companion. An examination of the X-ray light curves allows us to set preliminary lower limits to the size of an X-ray emitting corona …
Space Telescope observations of aurorae on the giant planets
Caldwell, J.; Wagener, R.
For the distant giant planets, Uranus and Neptune, the observation of aurorae may be the best astronomical technique for the detection of planetary magnetic fields, with implications for the structure and composition of their interiors. Aurorae may be detected by emssion of H I Ly α (1216 Å) and by H2 bands near 1600 Å. The latter are i…
Gamma rays from accreting matter onto collapsed objects
Giovannelli, F.; Karakula, S.; Tkaczyk, W.
In the spherical accretion onto massive objects, the matter may be heated up to temperatures as high as 1012 °K. In such a hot plasma, the thermal bremsstrahlung (e-e and e-p) and π° decay from inelastic collisions of protons are the main γ-ray sources. We determined the γ -ray production spectra from the π° decay and from bremsstrahlun…
Studies of high-latitude gamma rays
Strong, A. W.
COS-B gamma-ray data (70-5000 MeV) in the latitude range 10°< b <90° are compared with the expected emission from cosmic-ray interactions with interstellar gas. An additional component is found to be necessary to explain the latitude dependence of the emission. Two possible origins for this component are discussed: a gamma-ray halo around th…