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arXiv · 1106.3688

The Trigonometric Parallax of Cygnus X-1

Mark J. Reid·Jeffrey E. McClintock·Ramesh Narayan·Lijun Gou·Ronald A. Remillard·Jerome A. Orosz
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Abstract

We report a direct and accurate measurement of the distance to the X-ray binary Cygnus X-1, which contains the first black hole to be discovered. The distance of 1.86 (-0.11,+0.12) kpc was obtained from a trigonometric parallax measurement using the Very Long Baseline Array. The position measurements are also sensitive to the 5.6 d binary orbit and we determine the orbit to be clockwise on the sky. We also measured the proper motion of Cygnus X-1 which, when coupled to the distance and Doppler shift, gives the three-dimensional space motion of the system. When corrected for differential Galactic rotation, the non-circular (peculiar) motion of the binary is only about 21 km/s, indicating that the binary did not experience a large "kick" at formation.

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Mark J. Reid, Jeffrey E. McClintock, Ramesh Narayan, Lijun Gou, Ronald A. Remillard, Jerome A. Orosz. 2011-06-18. The Trigonometric Parallax of Cygnus X-1. https://doi.org/10.1088/0004-637x/742/2/83

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