SGR 1806−20
Explosion
Forty-two 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 of around −29. It was the brightest event known to have been sighted on this planet from an origin outside the Solar System until GRB 080319B. The magnetar released more energy in one-tenth of a second (1.0×10 J) than the Sun releases in 150,000 years (4×10 W × 4.8×10 s = 1.85×10 J). Such a burst is thought to be the largest explosion observed in this galaxy by humans since the SN 1604, a supernova observed by Johannes Kepler in 1604. The gamma rays struck Earth's ionosphere and created more ionization, which briefly expanded the ionosphere. The quake was equivalent to a magnitude 32 on the Richter scale.
A similar blast within 3 parsecs (10 light years) of Earth would severely affect the atmosphere, by destroying the ozone layer and causing mass extinction, and be similar in effect to a 12-kiloton nuclear blast at 7.5 kilometres (4.7 mi). The nearest known magnetar to Earth is 1E 1048.1-5937, located 9,000 light-years away in the constellation Carina.
Location
SGR 1806−20 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/most massive stars in the galaxy.
Planetary System
In 2024, a candidate exoplanet was found orbiting SGR 1806-20. It was found using Pulsar Timing.
SGR 1806-20 b is 0.0569 Jupiter masses or 18.08 Earth masses. SGR 1806-20 b is probably a hot Neptune with an orbital period of 238 days and a semi-major axis of 0.85 astronomical units. SGR 1806-20 b is notable for its eccentricity of 0.992, it the most eccentric exoplanet known.
See also
Notes
- ^ As measured by various space-based and land-based astronomical observatories, including the Swift spacecraft.
References
- ^ Manchester, R. N.; Hobbs, G.B.; Teoh, A.; Hobbs, M. "PSR J1808-2024 in the ATNF Pulsar Database". atnf.csiro.edu. Australia Telescope National Facility. Retrieved 9 January 2022.
- ^ "Top story – Scientists measure the most powerful magnet known". NASA, Goddard Space Flight Center. 2002-11-04. Archived from the original on 2010-04-28. Retrieved 2011-12-29.
- ^ "Cosmic Explosion Among the Brightest in Recorded History". NASA, Goddard Space Flight Center. 2005-02-18. Retrieved 2011-12-29.
- ^ Plait, Phil (2009-06-18). "OK, so maybe we can be a *little* frightened". Discover Magazine. Retrieved 2024-05-13.
- ^ Bob Berman (4 September 2015). "Weird Object: Magnetar SGR 1806-20". Astronomy.com. Retrieved 30 December 2020.
- ^ "Harvard-Smithsonian Center For Astrophysics: Blast Affected Earth From Halfway Across The Milky Way". ScienceDaily. 23 February 2005. Retrieved 30 December 2020.
- ^ https://exoplanet.eu/catalog/sgr_1806_20_b--10023/
- ^ https://arxiv.org/abs/2403.13333v1
- ^ https://www.aanda.org/articles/aa/full_html/2024/06/aa47828-23.html
External links
- Anniversary of a Cosmic Blast (Phil Plait Dec. 27, 2012)
- An exceptionally bright flare from SGR 1806-20 and the origins of short-duration big gamma-ray bursts, 2005-04-28 (Nature)
- 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) April 26, 2006