Sagittarius A

It consists of three components, the supernova remnant Sagittarius A East, the spiral structure Sagittarius A West, and a very bright compact radio source at the centre of the spiral, Sagittarius A*.

Many astronomers believe that there is evidence that there is a supermassive black hole at the centre of the galaxy. Sagittarius A* is agreed to be the most plausible candidate for the location of this supermassive black hole.

An international team led by Rainer Schödel[?] of the Max Planck Institute for Extraterrestrial Physics[?] observed the motion of the star S2[?] near to Sagittarius A* for a period of ten years, and obtained evidence that Sagittarius A* is a highly massive compact object. This is compatible with, and strong evidence in support of, the hypothesis that Sagittarius A* is a black hole.

From examining the Keplerian orbit of S2, they determined the mass of Sagittarius A* to be 3.7 ± 1.5 million solar masses, confined in an volume with a radius of 17 light-hours or less.

References

• Schödel, 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).

External links

• Recent Results of the MPE Infrared/Submillimeter Group (http://www.mpe.mpg.de/www_ir/ir_recent.php)
• Galactic Center Research at MPE (http://www.mpe.mpg.de/www_ir/GC/index)
• Nature report, with link to the Schödel et al. paper (http://www.nature.com/nature/links/021017/021017-5)
• The central lightyears: Sagittarius A* (http://www.mpifr-bonn.mpg.de/staff/hfalcke/bh/sld5)
• Sagittarius A East (http://chandra.harvard.edu/photo/cycle1/sgr_a/)