SGR 1806-20

Starbox begin
name=SGR 1806-20Starbox image


caption = This is where SGR 1806-20 would appear in the sky if it were visible to human eyes. Starbox observe
epoch=J2000
ra=18h 08m 39.32s
dec=-20° 24' 39.5"'
appmag_v= totally obscured
constell=Sagittarius
- style="vertical-align: top;"
Distance
50.000 light-years (14.5 kiloparsecs) Starbox catalog
names= GRB 790107, INTEGRAL1 84, AX 1805.7-2025 GRB 970912, INTREF 882, CXOU J180839.3-202439, HETE Trigger 1566, KONUS 07.01.79, EQ 1805.7-2025, HETE Trigger 3801, PSR J1808-2024, GBS 1806-20, HETE Trigger 3800, RX J1808.6-2024.

SGR 1806-20 is a magnetar, a particular type of neutron star. It has been identified as a soft gamma repeater. SGR 1806-20 is located about 14.5 kiloparsecs (50,000 light-years) from Earth on the far side of our Milky Way galaxy in the constellation of Sagittarius. It has a diameter of no more than 20 kilometres (12 miles) and rotates on its axis every 7.5 seconds (30,000 km/h rotation speed at the surface). As of 2007, SGR 1806-20 is the most magnetic object ever perceived by mankind, with a magnetic field over 10¹⁵ gauss in intensity ["Cosmic Explosion Among the Brightest in Recorded History" NASA date 02.18.05. [http://www.nasa.gov/vision/universe/watchtheskies/swift_nsu_0205.html] ] (compared to the Sun's 1-5 gauss).

Explosion

On December 27, 2004, the radiation from an explosion on the surface of SGR 1806-20 reached Earth.citeweb|url=http://www.gsfc.nasa.gov/topstory/20021030strongestmag.html|title=Top story - Scientists measure the most powerful magnet known|accessdate=14 December|accessyear=2007] In terms of gamma rays the burst was brighter than a full moon and had an absolute magnitude of around −29fn|1. It was the brightest event known to have been sighted on this planet from an origin outside our solar system. The gamma rays struck the ionosphere and created more ionization which briefly expanded the ionosphere. The magnetar released more energy in one-tenth of a second (1.3×10³⁹ J) than our sun has released in 100,000 years (4×10²⁶ W × 3.2×10¹² s = 1.3×10³⁹ J). Such a burst is thought to be the largest explosion observed by humans in the galaxy since the SN 1604 supernova observed by Johannes Kepler in 1604.

A similar blast within 3 parsecs (10 light years) of earth would destroy the ozone layer and would be similar to a 12 kt of TNT (50 TJ) nuclear blast at 7.5 km. The nearest known magnetar to earth is 1E 2259+586, 4 kiloparsecs (13,000 light years) away.

Location

SGR 1806-20 lies at the core of radio nebula G10.0-0.3 and is a component of cluster 1806-20, 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 one of the brightest/massive stars in the galaxy LBV 1806-20.

Gallery

ee also

* Cl* 1806-20 -- star cluster
* LBV 1806-20 -- luminous blue variable
* Magnetar
* Soft gamma repeater

External links

* [http://news.bbc.co.uk/1/hi/sci/tech/4278005.stm Huge 'star-quake' rocks Milky Way] , 2005-02-18, (BBC News Online)
* [http://www.space.com/scienceastronomy/bright_flash_050218.html Brightest galactic flash ever detected hits Earth] 2005-02-18 (space.com)
* [http://www.theage.com.au/articles/2005/02/19/1108709484471.html?from=top5] 2005-02-20 (The Age) Registration required.
* [http://www.space.com/scienceastronomy/050927_star_cracked.html Huge quake cracks star] 2005-09-27 (space.com)
* [http://www.spacedaily.com/reports/NASA_Sees_Hidden_Structure_Of_Neutron_Star_In_Starquake.html NASA Sees Hidden Structure Of Neutron Star In Starquake] (SpaceDaily) Apr 26, 2006

References

* [http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=SGR+1806-20&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id SIMBAD]

Notes

:*fnb|1 As measured by various space-based and land-based astronomical observatories, including the "Swift" spacecraft.