Astrophysics

Blast Wave Bounce

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Science  20 Oct 2006:
Vol. 314, Issue 5798, pp. 387
DOI: 10.1126/science.314.5798.387a

On 27 December 2004, a magnetic star, or magnetar, erupted. This event generated a huge burst of gamma rays that were spotted by gamma-ray and x-ray telescopes. In a fraction of a second, the magnetar SGR 1806–20 gave off as much energy as the Sun does in a quarter of a billion years. The energetic blast released by the star was sufficiently large for the generated gamma rays to affect Earth's environment when they arrived, causing ionosphere disturbances measured by radio receivers. Mandea and Balasis have found that currents set up in the ionosphere by the crashing gamma rays briefly upset Earth's magnetic field. The records of the CHAMP and DEMETER satellites contain a faint ringing signal of the magnetar's explosion with a period of 7.5 s for the duration of the flare. — JB

Geophys. J. Int., 10.1111/j.1365-246X.2006.03125.x (2006).

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