Search Publications
HST/STIS ultraviolet spectroscopy of the supersoft X-ray source RX J0439.8-6809
Rauch, T.; Gänsicke, B. T.; Beuermann, K. +3 more
We present ultraviolet observations of the supersoft X-ray source RX J0439.8-6809 obtained with the Hubble Space Telescope Imaging Spectrograph. The ultraviolet spectrum is a very blue continuum overlayed with interstellar absorption lines. The observed broad Lyalpha absorption line is consistent with an interstellar column density of neutral hydr…
Ultraluminous IRAS galaxy 10026+4347
Mao, S.; Boller, Th.; Wu, H. +4 more
We study optical and X-ray properties of the ultraluminous IRAS galaxy 10026+4347. This galaxy is a narrow-line QSO with very strong FeII emission. Three optical spectra were taken over two years. The full widths at half maximum (FWHMs) of the emission lines are constant whereas the third spectrum seems to show a continuum change. Intermediate-ban…
ET And, HD 219891, or HD 219668 - which one shows short-term variability?
Lehmann, H.; Scholz, G.; Hildebrandt, G. +1 more
The result of recent photometric observations of the CP star ET And, published by Weiss et al. (1998), shows that the known brightness variation of about 145 min has to be obviously assigned to the comparison star HD 219891. In order to test this statement we investigate the Hipparcos photometry of ET And, HD 219891 and the check star, HD 219668, …
CCD photometry and astrometry for visual double and multiple stars of the HIPPARCOS catalogue. I. Presentation of the large scale project
Cuypers, J.; Lampens, P.; Sinachopoulos, D. +7 more
A description is given of the activities of an international working group created with the aim of obtaining both photometric and astrometric observations of visual double and multiple stars with angular separations in the range of one to fifteen arcseconds, that formed part of the HIPPARCOS Input Catalogue. The scientific aims and realisations of…
The Wilson-Bappu relation for RS CVn stars
Doyle, J. G.; Özeren, F. F.; Jevremovic, D.
We investigate the extent to which the Wilson-Bappu relationship holds for chromospherically active binaries using the Mg ii h&k lines of 41 RS CVn stars observed with IUE. The resulting fits are different from the relationships obtained for single, less active stars. The parallax used were those from the hipparcos catalogue, these give a much…
Electron temperature diagnostics for the quiet Sun using SI BT IV lines
Curdt, W.; Mathioudakis, M.; Keenan, F. P. +3 more
We compare SUMER observations of six Si riptsize IV emission lines detected at the quiet Sun disk centre with recent theoretical line ratio calculations. Good agreement is found between theory and observation for ratios involving the 1394, 1403 and 818 Ä line intensities. This agreement supports the theoretical prediction that the temperature wher…
HD 42927 and HD 126341: two pulsating B stars surrounded by circumstellar dust
Aerts, C.; De Cat, P.; Malfait, K. +1 more
We have performed an infrared study of pulsating B stars. The main conclusion is that none of the 163 (non-)radial pulsators shows an IR excess flux due to free-free emission, despite the fact that the sample contains several rapid rotators. Two beta Cep stars and two slowly pulsating B stars do exhibit an unexpected infrared colour excess at 12 m…
The kinematics of RR Lyrae stars observed by HIPPARCOS
Chen, B.
We discuss the distributions of velocities and metallicities for 144 RR Lyrae stars observed by the Hipparcos astrometry satellite. The new absolute magnitude calibration of RR Lyrae stars and an all-sky reddening map have been used to derive individual distances accurately. Three statistical analysis techniques based on pattern recognition theory…
ISO far-infrared observations of rich galaxy clusters. I. Abell 2670
Nørgaard-Nielsen, H. U.; Pedersen, K.; Hansen, L. +3 more
As part of an investigation of far-infrared emission from rich galaxy clusters the central part of Abell 2670 has been mapped with ISO at 60 mu m, 100 mu m, 135 mu m, and 200 mu m using the PHT-C camera. Point sources detected in the field have infrared fluxes comparable to normal spirals at the cluster distance. Probable optical counterparts are …
Interplanetary scattering effects in the jovian bKOM radio emission observed by ULYSSES
MacDowall, R. J.; Woan, G.; Barrow, C. H.
The scattering of radio waves by the interplanetary medium (subsequently referred to simply as `scattering') imposes limitations on measurements of fine temporal and angular structure at low radio frequencies. The jovian broad-band kilometric radiation (bKOM) is highly structured and observations of this emission, by the Unified Radio and Plasma E…