Search Publications
High-dispersion spectroscopy of the Of/WN stars R 84 and S 61 of the Large Magellanic Cloud.
Stahl, O.; Wolf, B.; Seifert, W.
The Of/WN stars R 84 and S 61 of the LMC have been studied with high-dispersion spectroscopy in the optical and satellite-UV range. The high resolution and high S/N spectra in the optical range are particularly distinguished by strong emission lines of H, He I and [N II]. The comparison of R 84 with S 61 shows that the peculiar emission line spect…
Soft X-ray imaging observations of the 39 millisecond pulsar PSR 1951+32.
Buccheri, R.; Oegelman, H.
The authors report observations of the newly discovered 39.5 millisecond pulsar PSR 1951+32 with the soft X-ray telescope on board the EXOSAT observatory. A point-like source coincident with the position of the pulsar was observed. For a power-law model with photon index of -2, a column density of 6×1021cm-2, and a distance o…
EXOSAT observations of the magnetic binary system E 1114+182.
Pietsch, W.; Schaaf, R.; Biermann, P.
In this short note we present EXOSAT X-ray light curves of the magnetic binary system E1114+182 for two epochs. The epochs of the eclipse minima follow closely the ephemeris of Biermann et al., demonstrating that the period has not changed since the first observation with the EINSTEIN X-ray observatory in 1979. We compare the new X-ray llght curve…
The Ultraviolet Spectrum of Beta Lyrae
Mazzali, Paolo A.
The high-resolution UV spectrum of Beta Lyrae observed with the IUE satellite between 1980 and 1986 is analyzed. A complete list of line identifications for the entire spectral range of the IUE (1225-3125 A) is presented. The main spectral features are P Cygni profiles of resonance lines of high ionization states typical of stellar winds, some of …
The formation of iron features in the cooling spectrum of X-ray bursts.
Fabian, A. C.; Ross, R. R.; Foster, A. J.
A detailed calculation of the formation and detection of iron spectral features in X-ray bursts is presented. Observation of these features will enable the mass and radius of a neutron star to be estimated separately. Comptonization and free-free absorption and emission processes are taken into account, as well as the effects of iron in its last f…
The Halley multicolour camera
Wilhelm, K.; Keller, H. U.; Kramm, J. R. +22 more
The Halley multicolor camera (HMC) is a high-resolution imaging system on board the ESA Giotto spacecraft to comet Halley. The fast spin of this spacecraft (15 RPM) required a unique and highly specialized design and complex fully autonomous operation. Design criteria and trade-offs and operational aspects are emphasized in this instrument descrip…
Hard X-ray observations of the quasar 3C 273.
Damle, S. V.; Kunte, P. K.; Naranan, S. +2 more
The quasar 3C 273 was observed with a balloon-borne phoswich scintillator detector system launched on December 12, 1983 from Hyderabad, India. 3C 273 was tracked for 130 minutes and the background was measured in the same ranges of elevation and azimuth when the source was not in the field of view, for approximately the same duration. The fluxes i…
Changes in the Soft and Hard X-Ray Lightcurves of the Am-Herculis Object E:1405-451
Cristiani, S.; Cropper, M.; Osborne, J. P.
The preliminary results of EXOSAT and contemporaneous optical observations of E1405-451 (V834 Cen) in 1985 and 1986 are presented. In the latter of the two observations the soft X-ray light curve was observed to be quite different to that seen in all previous observations, but similar to the optical light curve and the new soft X-ray light curve o…
A study of UV spectra of zeta Aur/VV CEP stars. X. Mass-loss of alphaSco A from high-resolution IUE spectra of alpha SCO B.
Reimers, D.; Hagen, H. -J.; Hempe, K.
We redetermine the rate of mass-loss of the M super- giant α Sco by means of circumstellar lines observed with IUE in the ultraviolet spectrum of its B star companion. We first show 1) that nearly all UV lines, on which previous mass-loss determinations (v.d. Hucht et al., 1978; Bernat, 1982) were based, are blends with interstellar lines and 2) t…
IUE observations of CH Cygni continuum during 1979–1986
Hack, M.; Mikolajewska, J.; Selvelli, P. L.
Variations of the UV continuum have been analyzed. The observed UV continuum may be reproduced by a superposition of a Kurucz model atmosphere (log g=2), Teff∼8500–15000 K) and optically thin hydrogen bound-free and free-free emission (Te∼ 1000 K). The temperature of the Kurucz atmosphere is the lowest at the maximum of brigh…