Coordinated observation of the massive system 4U 1700+24 = HD 154791.
Abstract
The authors report results from multifrequency observations of the X-ray source 4U 1700+24 / HD 154791. This source was observed simultaneously with the EXOSAT and IUE satellites on March 25, 1985, and it is continuously monitored in the optical band at the Bologna Astronomical Observatory since July 1984. Their observations show source features which are different from those measured during previous observations. The X-ray spectrum is significantly softer than in previous measurements, and much more absorbed; high excitation lines in UV spectra (C IV and N V) have disappeared; the optical spectrum, despite a fairly good photometric stability of the M giant HD 154791 in V and B bands also shows differences with respect to previous observations. The authors discuss their results in the framework of both a binary model and a coronal model. They point out that their observations strengthen the hypothesis that the X-ray emission is due to mass accretion onto a compact object orbiting around the M giant star HD 154791.
- Publication:
-
Nuovo Cimento C Geophysics Space Physics C
- Pub Date:
- April 1990
- Bibcode:
- 1990NCimC..13..481D
- Keywords:
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- Ultraviolet Astronomy;
- X Ray Sources;
- Exosat Satellite;
- Iue;
- Visible Spectrum;
- X-Ray Binaries: X-Ray Spectra;
- X-Ray Binaries: UV Spectra