A Magnetar is a form of neutron star that sometimes forms after the supernova collapse of a star about 40 times as massive as our sun. It's believed that about 1 in 10 supernovas results in a magnetar. Celestial phenomena such as soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are currently believed to be Magnetars.
Magnetars are tiny, only about 20 km in diameter, but are more massive than our sun. Most rotate very rapidly - at least several times per second. Magnetars only come from supernovas where the star sheds about 80% or 90% of it's mass. If it sheds less than that, the supernova will instead leave behind a black hole, neutron star, or pulsar.
Magnetars are expected to have lifespans that are relatively short in astronomical terms - only about 10,000 years or so.
Magnetars have extremely strong magnetic fields - possibly as high as 10 gigateslas. That's enough to warp human flesh, should a space ship get too close. It would, of course, mess with instruments and navigation at much greater ranges. Magnetars experience starquakes, which cause them to release huge spikes of gamma ray and x-ray radiation. The presence of a Magnetar within 10 Light Years of a planet will bombard that planet with so much energy that all the ozone from the planet will burned off.
On December 27, 2004, the earth was hit by a burst of gamma rays that was powerful enough to have measurable effects on our upper atmosphere - that burst came from SGR 1806-20, a magnetar 50,000 light years away from the earth. Luckily, these flares don't hit us very often - we've only detected them in 1979, 1998, and 2004.
Game and Story Use
- Magnetars are a great hazard for space explorers, a danger that can destroy civilizations.
- The inverse square law gives us an idea of their range and potency. The effects were measurable, but not alarming, on earth from 50,000 light years away. At 25,000 LY, the effect will be four times as powerful. At 12,500 LY, it's 16 times as powerful. At 6,250 LY, it's 64 times as potent. I'm not sure at exactly what range it starts/stops threatening health effects and ecological disaster), but whatever that range is, it will affect a spherical region of space many light years in diameter.
- December 27, 2004 is a great date for a character's superhero powers to awaken. Bombarded by interstellar radiation, he became "The Amazing Magnetar''.