Starburst across galaxy impacts Earth's ionosphere

Sunday, February 20, 2005

A flash of energy from across the galaxy on December 27 was 100 times larger than any previously seen. The x-ray burst was powerful enough to affect our ionosphere in the same way a solar flare does.

According to astronomers at the NRAO, the enormous energy burst from a remote magnetar was likely caused by an abrupt adjustment, or "starquake", in the outer layer of the magnetar, causing a "catastrophic" disruption of its magnetic field.

More energy was released in a tenth of a second than our sun has emitted since the dawning of the human race.

The magnetar, known as SGR 1806-20, is 50,000 light years away in the direction of the constellation Sagittarius. That places it on the opposite side of our Milky Way galaxy, which is roughly a disk 100,000 light years across.

Magnetars are a rare type of neutron star with unusually strong magnetic fields. SGR 1806-20 is only 20 kilometers in diameter, rotates once every 7.5 seconds, and has a mass comparable to our sun.

Neutron stars are stars which have exhausted their nuclear fuel and collapsed. There are no electrons or atoms in the cores of these massive objects, just neutrons packed tightly together.

An article from the Harvard-Smithsonian Center for Astrophysics will be published soon in Nature magazine.

Center for Astrophysics at Harvard University