# Magnetar SGR 1806-20

By [Manstrong](https://paragraph.com/@manstrong) · 2023-08-18

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SGR 1806-20 is a Magnetar, a type of neutron star with a very powerful magnetic field. It was discovered in 1979 and identified as a soft gamma repeater. SGR 1806-20 is located approximately 14.5 kiloparsecs (50,000 light years) away from Earth on the far side of the Milky Way in the constellation Sagittarius. It has a diameter of no more than 20 km and rotates around its axis every 7.5 seconds (the rotation speed on the surface is 30,000 km/h). As of 2016, SGR 1806-20 is the most strongly magnetized object ever observed, with a magnetic field in excess of 1015 Gauss (G) (1011 Tesla) in intensity. For comparison, the magnetic field of the Sun is from 1 to 5 G, and the Earth is from 0.25 to 0.65 G.

**_Explosion_**

50 thousand years after the stellar earthquake occurred on the surface of SGR 1806-20, the radiation from the resulting explosion reached the Earth on December 27, 2004. In terms of gamma radiation, the explosion had an absolute magnitude of about -29. It was the brightest event that was seen on our planet from a source outside the Solar System. The magnetar released more energy in one tenth of a second (1.0 ×1040 J) than the Sun in 150 thousand years (1.85 × 1039 J). It is believed that such an explosion is the largest explosion observed in our galaxy by humans since the supernova SN 1604, which was observed by Johannes Kepler in 1604. Gamma rays hit the Earth's ionosphere and created additional ionization, which briefly expanded the ionosphere.

A similar explosion within 3 parsecs (10 light years) It would destroy the ozone layer from the Earth and would be essentially similar to a 12 kiloton nuclear explosion at a distance of 7.5 km . The closest known Magnetar to Earth is 1E 1048.1—5937, located at a distance of 9 thousand light-years in the constellation Kiel.

![](https://storage.googleapis.com/papyrus_images/0f1083dd05b54ecbef1d34b71a75ba77926f3f675d7c4a167385045b077a8075.png)

**_Magnetar location_**

The magnetar SGR 1806-20 lies at the core of the radio fog G10.0-0.3 and is a member of an open cluster named after it, the component W31 itself, one of the largest H II regions in the Milky Way. Cluster 1806-20 consists of several very 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.

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*Originally published on [Manstrong](https://paragraph.com/@manstrong/magnetar-sgr-1806-20)*