SGR 1806-20
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 This is where SGR 1806-20 would appear in the sky if it were visible to human eyes. |
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| Observation data Epoch J2000 |
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|---|---|
| Constellation (pronunciation) |
Sagittarius |
| Right ascension | 18h 08m 39.32s |
| Declination | -20° 24' 39.5"' |
| Characteristics | |
| U-B color index | ? |
| B-V color index | ? |
| Variable type | None |
| Astrometry | |
| Distance | 50.000 light-years (14.5 kiloparsecs) |
| Details | |
| Mass | ? M☉ |
| Radius | ? R☉ |
| Luminosity | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | ? |
| Age | ? years |
| Other designations | |
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 (compare to the Sun's 1-5 gauss)
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[edit] Explosion
On December 27, 2004, the radiation from an explosion on the surface of SGR 1806-20 reached Earth.[1] In terms of gamma rays the burst was brighter than a full moon and had an absolute magnitude of around −291. 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.
[edit] 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.
[edit] Gallery
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[edit] External links
- Huge 'star-quake' rocks Milky Way, 2005-02-18, (BBC News Online)
- Brightest galactic flash ever detected hits Earth 2005-02-18 (space.com)
- [1] 2005-02-20 (The Age) Registration required.
- Huge quake cracks star 2005-09-27 (space.com)
- NASA Sees Hidden Structure Of Neutron Star In Starquake (SpaceDaily) Apr 26, 2006
[edit] References
- [Simdab]
[edit] Notes
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- Note 1: As measured by various space-based and land-based astronomical observatories, including the Swift spacecraft.
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