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Observation data
Epoch       Equinox
Constellation Sagittarius
Right ascension
Distance 25900 ± 1400 ly
(7940 ± 420 pc)
Companion Sagittarius A*
Period (P) 11.5 ± 0.3 yr
Eccentricity (e) 0.68 ± 0.02
Inclination (i) 151 ± 3°
Longitude of the node (Ω) 175 ± 5°
Periastron epoch (T) 2009.5 ± 0.3
Argument of periastron (ω)
185 ± 9°
Other designations
[GKM98] S0-102.
Database references

S0-102 is a star that is located very close to the centre of the Milky Way, near the radio source Sagittarius A*, orbiting it with an orbital period of 11.5 years. As of 2012 it is the shortest known period star orbiting the black hole at the centre of the Milky Way. This now beats the record set by S0-2 of 16 years. The star was identified by a University of California, Los Angeles team headed by Andrea M. Ghez.[1] At its perihelion, its speed exceeds 1% of the speed of light.[2]

Its position in the sky has been monitored from 2000 to 2012 using the W. M. Keck telescope. One complete orbit has been observed. It travels in a clockwise direction. Having observed two stars orbiting through complete periods around the centre, the gravitational potential of SgrA* can be established. Possibly there is a great deal of dark matter around the orbits of these stars. Also general relativistic effects due to gravitational redshift should become observable.[3]

Orbits of S0-2 and S0-102 around the Milky Way galaxy's supermassive black hole.


  1. ^ Stuart Wolpert (4 October 2012). "UCLA astronomers discover star racing around black hole at center of our galaxy". 
  2. ^ "S0-102". 20 October 2012. 
  3. ^ Meyer, L.; Ghez, A. M.; Schödel, R.; Yelda, S.; Boehle, A.; Lu, J. R.; Do, T.; Morris, M. R.; Becklin, E. E.; Matthews, K. (2012). "The Shortest-Known-Period Star Orbiting Our Galaxy's Supermassive Black Hole". Science 338 (6103): 84–87. doi:10.1126/science.1225506. PMID 23042888.  edit

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