Sagittarius A (or Sgr A) is a complex radio source at the center of our galaxy, the Milky Way. It is located in the sky in the Sagittarius constellation. The Galactic Center is the rotational center of the Milky Way galaxy. ... Jump to: navigation, search NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 56,000 light years in diameter and approximately 60 million light years distant. ... Jump to: navigation, search A NASA artists conception of what the Milky Way would look like if seen off-axis. ... Sagittarius ( , and Latin for Archer) is a constellation of the zodiac, commonly depicted as a centaur drawing a bow. ...

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*. In computer science, components are basic functional units of a program which allow for rapid development. ... Jump to: navigation, search Remnant of Keplers Supernova, SN 1604. ... Remnant of Keplers Supernova, SN 1604. ... Sagittarius A* (pronounced A-star) is a bright and very compact source of radio emission at the center of the Milky Way Galaxy, part of a larger astronomical feature at that location (Sagittarius A). ...

Many astronomers believe that there is evidence that there is a supermassive black hole at the center of the galaxy. Sagittarius A* is agreed to be the most plausible candidate for the location of this supermassive black hole. Jump to: navigation, search Top: artists conception of a supermassive black hole drawing material from a nearby star. ...

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. 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 a volume with a radius of 17 light-hours (120 AU) or less. The Max Planck Institute for Extraterrestrial Physics is a Max Planck Institute, located in Garching, near Munich, Germany. ... S2 is a star that is located close to the radio source Sagittarius A*, orbiting it with an orbital period of 15. ... ... Jump to: navigation, search The astronomical unit (AU or au or a. ...

This is compatible with, and strong evidence in support of, the hypothesis that Sagittarius A* is a black hole.

Several teams of researchers, including groups at the National Radio Astronomy Observatory and at the Shanghai Astronomical Observatory, have attempted to image Sagittarius A* in the radio spectrum using Very Long Baseline Interferometry. The images obtained have been consistent with the Saggitarius A* radio emissions being associated with the accretion disc and polar jets of a supermassive black hole. The National Radio Astronomy Observatory (NRAO) is an institution set up by the United States government for the purpose of radio astronomy. ... Very Long Baseline Interferometry (VLBI) is a type of interferometry in which the data received at each antenna in the array is paired with timing information, usually from a local atomic clock, and then stored for later analysis on magnetic tape or hard disk. ... Artists conception of a binary star system with one black hole and one main sequence star An accretion disc (or accretion disk) is a structure formed by material falling into a gravitational source. ... A polar jet is a phenomenon often seen in astronomy. ...

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).446

External links

• Recent Results of the MPE Infrared/Submillimeter Group
• Galactic Center Research at MPE
• Nature report, with link to the Schödel et al. paper
• The central lightyears: Sagittarius A*
• Sagittarius A East
• Chandra Photo Album Sagittarius A
• The Proper Motion of Sgr A* and the Mass of Sgr A*
• CNN article regarding VLBI radio imaging of Sgr A*
• NRAO article regarding VLBI radio imaging of Sgr A*