Sgr A* ``Visual Binaries'': A Direct Measurement of the Galactocentric Distance

Abstract

We present a new geometrical method for measuring the distance to the Galactic center (R_0) by solving for the Keplerian orbit of individual stars bound to the black hole associated with the Sgr A* from radial velocity and proper motion measurements. We identify three stars to which the method may be applied, and show that 1-5 % accuracy of R_0 can be expected after 15 years of observing, and 0.5-2 % after 30 years of observing, depending on what the orbital parameters of these three stars turn out to be. Combining the measurements of the three stars with favorable orbital parameters leads to even more precise values. In the example that we present, such combined solution yields 4 % accuracy already by the year 2002. All these estimates assume that annual position measurements will continue to be made with the 2 mas precision recently reported by Ghez et al. The precision of the distance measurement is relatively insensitive to the radial velocity errors, provided that the latter are less than 50 km/s. Besides potentially giving an estimate of R_0 that is better than any currently in use, the greatest advantage of this method is that it is free from systematic errors.

Submitted to ApJ, 14 pages, 8 figures

References in corpus (7)

• High Proper Motion Stars in the Vicinity of Sgr A*: Evidence for a Supermassive Black Hole at the Center of Our Galaxy
• Distance to M31 With the HST and Hipparcos Red Clump Stars
• Galactic Kinematics of Cepheids from Hipparcos Proper Motions
• Galactocentric Distance With the OGLE and Hipparcos Red Clump Stars
• Systematics of RR Lyrae Statistical Parallax III: Apparent Magnitudes and Extinctions
• The Shape and Scale of Galactic Rotation from Cepheid Kinematics
• Sgr A^*: A supermassive black hole or a spatially extended object?

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