Many galaxies are thought to have supermassive black holes at their centres1—more than a million times the mass of the Sun. Measurements of stellar velocities2,3,4,5,6,7 and the discovery of variable X-ray emission8 have provided strong evidence in favour of such a black hole at the centre of the Milky Way, but have hitherto been unable to rule out conclusively the presence of alternative concentrations of mass. Here we report ten years of high-resolution astrometric imaging that allows us to trace two-thirds of the orbit of the star currently closest to the compact radio source (and massive black-hole candidate) Sagittarius A*. The observations, which include both pericentre and apocentre passages, show that the star is on a bound, highly elliptical keplerian orbit around Sgr A*, with an orbital period of 15.2 years and a pericentre distance of only 17 light hours. The orbit with the best fit to the observations requires a central point mass of (3.7 ± 1.5) × 106 solar masses (M⊙). The data no longer allow for a central mass composed of a dense cluster of dark stellar objects or a ball of massive, degenerate fermions.
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Kormendy, J. & Richstone, D. Inward bound—The search for supermassive black holes in galactic nuclei. Annu. Rev. Astron. Astrophys. 33, 581–624 (1995)
Eckart, A. & Genzel, R. Observations of stellar proper motions near the Galactic Centre. Nature 383, 415–417 (1996)
Genzel, T., Eckart, A., Ott, T. & Eisenhauer, F. On the nature of the dark mass in the centre of the Milky Way. Mon. Not. R. Soc. 291, 219–234 (1997)
Ghez, A., Klein, B. L., Morris, M. & Becklin, E. E. High proper-motion stars in the vicinity of Sagittarius A*: Evidence for a supermassive black hole at the center of our galaxy. Astrophys. J. 509, 678–686 (1998)
Genzel, R., Pichon, C., Eckart, A., Gerhard, O. & Ott, T. Stellar dynamics in the Galactic Centre: proper motions and anisotropy. Mon. Not. R. Soc. 317, 348–374 (2000)
Ghez, A., Morris, M., Becklin, E. E., Tanner, A. & Kremenek, T. The accelerations of stars orbiting the Milky Way's central black hole. Nature 407, 349–351 (2000)
Eckart, A., Genzel, R., Ott, T. & Schödel, R. Stellar orbits near Sagittarius A*. Mon. Not. R. Soc. 331, 917–934 (2002)
Baganoff, F. K. et al. Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre. Nature 413, 45–48 (2001)
Backer, D. C. & Sramek, R. A. Proper motion of the compact, nonthermal radio source in the Galactic Center, Sagittarius A*. Astrophys. J. 524, 805–815 (1999)
Reid, M. J., Readhead, A. C. S., Vermeulen, R. C. & Treuhaft, R. The proper motion of Sagittarius A*. I. First VLBA results. Astrophys. J. 524, 816–823 (1999)
Lenzen, R., Hofmann, R., Bizenberger, P. & Tusche, A. CONICA: the high-resolution near-infrared camera for the ESO VLT. Proc. SPIE IR Astron. Instrum. (ed. Fowler, A. M.) 3354, 606–614 (1998).
Rousset, G. et al. Design of the Nasmyth adaptive optics system (NAOS) of the VLT. Proc. SPIE Adapt. Opt. Technol. (eds Bonaccini, O. & Tyson, R. K.) 3353, 508–516 (1998).
Brandner, W. et al. NAOS + CONICA at YEPUN: First VLT adaptive optics system sees first light. ESO Mess. 107, 1–6 (2002)
Menten, K. M., Reid, M. J., Eckart, A. & Genzel, R. The position of Sagittarius A*: Accurate alignment of the radio and infrared reference frames at the Galactic Center. R. Astrophys. J. 475, L111–L115 (1997)
Gudehus, D. H. A multiple-star combined solution program — Application to the population II binary µ Cas. Am. Astron. Soc. Meeting 198, 1–13 (2001)
Maoz, E. Dynamical constraints on alternatives to supermassive black holes in Galactic Nuclei. Astrophys. J. 494, L181–L184 (1998)
Tsiklauri, D. & Viollier, R. D. Dark matter concentration in the Galactic Center. Astrophys. J. 500, 591–595 (1998)
Munyaneza, F. & Viollier, R. D. The motion of stars near the Galactic Center: A comparison of the black hole and fermion ball scenarios. Astrophys. J. 564, 274–283 (2002)
Torres, D. F., Capozziello, S. & Liambase, G. Supermassive boson star at the galactic centre? Phys. Rev. D 62, 104012 (2000)
Rubilar, G. T. & Eckart, A. Periastron shifts of stellar orbits near the Galactic center. Astron. Astrophys. 374, 95–104 (2001)
Reid, M. J. The distance to the center of the Galaxy. Annu. Rev. Astron. Astrophys. 31, 345–372 (1993)
Chakrabarty, D. & Saha, P. A non-parametric estimate of the mass of the central black hole in the Galaxy. Astron. J. 122, 232–241 (2001)
Reid, M. J. et al. The position of Sagittarius A*: II. Accurate positions and proper motions of stellar SiO masers at the Galactic Center. Astrophys. J. (submitted)
We thank the teams who developed and constructed the near-infrared camera CONICA and the adaptive optics system NAOS. We are grateful to all the instrument scientists and European Southern Observatory staff involved in the commissioning of NAOS/CONICA for observations of the Galactic Centre. We thank C.H. Townes and J. Kormendy for comments. We thank D. Gudehus for assistance with the Binary-Star Combined Solution Program.
The authors declare that they have no competing financial interests.
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Schödel, R., Ott, T., Genzel, R. et al. A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way. Nature 419, 694–696 (2002). https://doi.org/10.1038/nature01121
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