page_title: SGR 1806−20
section_title: Explosion
hierarchical_section_title: SGR 1806−20 / Explosion
caption_attribution_description: English: An artist conception of the SGR 1806-20 magnetar including magnetic field lines Français&#160;: Une vue d'artiste de SGR 1806-20, une magnétar. Nederlands: Neutronenster. Norsk bokmål: En kunstners tolkning av SGR 1806-20 magnetaren, inkludert linjer for magnetfeltet. Polski: Eksplozja na powierzchni magnetara, na rysunku widoczne są linie pola magnetycznego – wizja artysty (Źródło: NASA). Eksplozja na SGR&#160;1806-20, linie reprezentują pole magnetyczne – wizja artysty (Źródło: NASA). Svenska: En konstnärs tolkning av magnetaren SGR 1806-20 med tänkta magnetfältslinjer inritade.
context_page_description: SGR 1806−20 is a magnetar, a type of neutron star with a very powerful magnetic field, that was discovered in 1979 and identified as a soft gamma repeater. SGR 1806−20 is located about 14.5 kiloparsecs from Earth on the far side of the Milky Way in the constellation of Sagittarius. It has a diameter of no more than 20 kilometres and rotates on its axis every 7.5 seconds. As of 2016, SGR 1806-20 is the most highly magnetized object ever observed, with a magnetic field over 10¹⁵ gauss in intensity.
context_section_description: Fifty thousand years after a starquake occurred on the surface of SGR 1806-20, the radiation from the resultant explosion reached Earth on December 27, 2004 (GRB 041227). In terms of gamma rays, the burst had an absolute magnitude around −29. It was the brightest event known to have been sighted on this planet from an origin outside the Solar System, until the GRB 080319B. The magnetar released more energy in one-tenth of a second (1.0×10⁴⁰ J) than the Sun releases in 150,000 years (4×10²⁶ W × 4.8×10¹² s = 1.85×10³⁹ J). Such a burst is thought to be the largest explosion observed in this galaxy by humans since the SN 1604 supernova observed by Johannes Kepler in 1604. The gamma rays struck Earth's ionosphere and created more ionization, which briefly expanded the ionosphere.
  A similar blast within 3 parsecs (10 light years) of Earth would destroy the ozone layer and be similar in effect to a 12-kiloton nuclear blast at 7.5 kilometers. The nearest known magnetar to Earth is 1E 1048.1-5937, located 9,000 light-years away in the constellation Carina.
caption: Artist rendering of central neutron star
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