Sagittarius A* cluster

Inferred orbits of 6 stars around supermassive black hole candidate Sagittarius A* at the Milky Way's center[1]

The Sagittarius A* cluster is the cluster of stars in close orbit around Sagittarius A*, the supermassive black hole at the center of the Milky Way (in the Galactic Center). The individual stars are often listed as "S-stars", but their names and IDs are not formalized, and stars can have different numbers in different catalogues.

One of the most studied stars is S2, a relatively bright star that also passes close by Sgr A*.

As of 2020, S4714 is the current record holder of closest approach to Sagittarius A*, at about 12.6 astronomical units (1.88×109 km), almost as close as Saturn gets to the Sun, traveling at about 8% of the speed of light. These figures given are approximate, the formal uncertainties being 12.6±9.3 au and 23928±8840 km/s. Its orbital period is 12 years, but an extreme eccentricity of 0.985 gives it the close approach and high velocity.[2]

  1. ^ Eisenhauer, F.; et al. (July 20, 2005). "SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month". The Astrophysical Journal. 628 (1): 246–259. arXiv:astro-ph/0502129. Bibcode:2005ApJ...628..246E. doi:10.1086/430667. S2CID 122485461.
  2. ^ Peißker, Florian; Eckart, Andreas; Zajaček, Michal; Basel, Ali; Parsa, Marzieh (August 2020). "S62 and S4711: Indications of a Population of Faint Fast-moving Stars inside the S2 Orbit—S4711 on a 7.6 yr Orbit around Sgr A*". The Astrophysical Journal. 889 (50): 5. arXiv:2008.04764. Bibcode:2020ApJ...899...50P. doi:10.3847/1538-4357/ab9c1c. S2CID 221095771.