Measuring Distance And Properties Of The Milky Way's Central Supermassive Black Hole With Stellar Orbits

We report new precision measurements of the properties of our Galaxy's supermassive black hole. Based on astrometric (1995-2007) and radial velocity (RV; 2000-2007) measurements from the W. M. Keck 10m telescopes, a fully unconstrained Keplerian orbit for the short- period star S0- 2 provides values for the distance (R(0)) of 8.0 +/- 0.6 kpc, the enclosed mass (Mbh) of 4.1 +/- 0.6; 10(6) M(circle dot), and the black hole's RV, which is consistent with zero with 30 km s(-1) uncertainty. If the black hole is assumed to be at rest with respect to the Galaxy (e. g., has no massive companion to induce motion), we can further constrain the fit, obtaining R(0) = 8.4 +/- 0.4 kpc and M(bh) 4.5 +/- 0.4; 10(6) M(circle…

• NS
  National Science Foundation
• NA
  National Aeronautics and Space Administration
• WM
  W. M. Keck Foundation
• UO
  University of California, Santa Cruz
• CI
  California Institute of Technology