The BBXRT Observation of Centaurus X-3

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Session 69 -- Cataclysmic Variables and Pulsars
Oral presentation, Thursday, 10:30-12:00, Dwinelle 155 Room

[69.07] The BBXRT Observation of Centaurus X-3

M. D. Audley, R. L. Kelley (NASA/GSFC)

The binary X-ray pulsar Cen X-3 was observed for about 1600 sec with the Broad Band X-Ray Telescope (BBXRT) in December 1990. This instrument consisted of a conical X-ray telescope and a Si/Li detector covering the range 0.3 - 12 keV with an energy resolution of 150 eV at 6 keV. This energy resolution was some four times better than previously attained. During the observation Cen X-3 was in the post-egress state with an orbital phase of about 0.27 measured from mid-eclipse. The unabsorbed luminosity of the source in the 2-10 keV band was found to be $3.7\times 10^{37}$ erg/sec, assuming a distance of 8.5 kpc. The spectrum in this energy range is best fit by a power law with interstellar absorption and line emission at 6.7 keV from H- and He-like Fe. The power law index and absorption column vary with pulse phase, which suggests that the spectrum is actually more complex than a simple power law. The Fe line has a width of about 280 eV and an amplitude that may vary with the pulse phase. This indicates that emission by H- and He-like Fe is responsible for the previously observed pulsation of the iron line (Day et al., 1992). There is also evidence for an iron fluorescence line at 6.4 keV.

Thursday program listing