Magnetar SGR 1806-20.
SGR 1806-20 is a magnetar about 50,000 light-years from Earth. It is a rare type of neutron star, a stellar remnant of a dying star with a particularly powerful magnetic field strong enough to destroy your old floppy disk collection from millions of miles away. When smaller stars get old, they expand into the red giant stage and afterwards start to collapse inward, becoming things like neutron stars and white dwarfs. Magnetars are the rarest and only 21 have ever been discovered. SGR 1806-20 was discovered in 1979 and is located on the far side of the Milky Way galaxy in the constellation of Sagittarius. It lies at the core of radio nebula G10.0-0.3 and is a member of an open cluster named after it, itself a component of W31, one of the largest H II regions in the Milky Way. Cluster 1806-20 is made up of some highly unusual stars, including at least two carbon-rich Wolf–Rayet stars (WC9d and WCL), two blue hypergiants, and LBV 1806-20, one of the brightest and most massive stars in the galaxy.
A starquake occurred and the radiation from an explosion on the surface of SGR 1806-20 reached Earth on December 27, 2004. Scientists detected a flash of light from across the Galaxy so powerful that it bounced off the Moon and lit up the Earth’s upper atmosphere. The flash was brighter than anything ever detected from beyond our Solar System and lasted over a tenth of a second. In terms of gamma rays, the burst had an absolute magnitude around −29’. The magnetar released more energy in one-tenth of a second than the Sun has released in 100,000 years. Such a burst is thought to be the largest explosion observed in the galaxy by humans since the SN 1604 supernova observed by Johannes Kepler in 1604. The gamma rays struck the Earth ionosphere and created more ionization, which briefly expanded the ionosphere. A similar blast within 10 light years of Earth would destroy the ozone layer and would be similar in effect to a 12 kt of TNT nuclear blast at 7.5 km.
It is currently the most highly-magnetized object to have ever been observed, having a magnetic field that is 1-2 quadrillion (short scale) times stronger than that of the Earth. Even more incredible, SGR 1806-20 is only twelve miles long, rotating every 7.5 seconds (30,000 km/h rotation speed at the surface). In spite of its tiny size, it has a mass of more than twelve times that of the Sun. It is also about three million times brighter than the Sun. If you were to pick an amount of matter the size of a grain of sand from SGR 1806-20, it would weigh more than a jumbo jet!
Credit: NASA, Wikipedia.