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Astron. Astrophys. 350, 1085-1088 (1999)

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Research Note

The distance to eight X-ray sources derived from Hipparcos observations

L. Lee Clark 1 and Joseph F. Dolan 2

1 Department of Astronomy, San Diego State University, San Diego, CA 92182-1221, USA (clark@vega.sdsu.edu)
2 Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA (tejfd@splvin.gsfc.nasa.gov)

Received 23 March 1999 / Accepted 4 August 1999


The parallaxes of eight galactic X-ray sources measured by Hipparcos are consistent with zero in all but two cases, 4U1145-619 (= Cen X-5) and HZ43. The parallax and proper motion measured for each of the others, including the Be/neutron star binaries X Per and A0535+26 and the massive X-ray binaries 4U0900-40, 4U1700-37, and Cyg XR-1, are consistent with their spectroscopic parallaxes. These results provide no evidence that visible stars in X-ray binaries have a luminosity that is abnormal for their spectral type.

Key words: astrometry – stars: distances – stars: kinematics – X-rays: stars

Send offprint requests to: J.F. Dolan

Correspondence to: J.F. Dolan (tejfd@splvin.gsfc.nasa.gov)

© European Southern Observatory (ESO) 1999

Online publication: October 14, 1999