Astronomers have now discovered 23 confirmed magnetars, but only one, in Cassiopeia, is visible through optical telescopes. Astronomers detected the others solely by the types of radiation they emit. The nearest is a less than 9,000 light-years away, and more than a million other unknown magnetars are thought to loiter unseen in the dusty hallways of our Milky Way.
More bursts arrived since that first eye-opener. The biggest came on December 27, 2004. This magnetar emitted more energy in a tenth of a second than our Sun has released in 100,000 years! If it were located within 10 light-years of us, it would have obliterated our planet’s ozone layer and caused mass extinction.
The source, utterly invisible in visible light, lurks directly behind the center of our galaxy, on the opposite side of the Milky Way, some 50,000 light-years away. Its name is SGR 1806–20. This object in the constellation Sagittarius is the most magnetic object ever perceived.
Victoria Kaspi of McGill University in Montreal, Quebec, Canada, won the 2004 Herzberg Medal for her studies of these fantastic objects, and she remains obsessed with them. “Magnetars are the only deep-space objects to directly affect Earth,” she says. “The 2004 burst [from SGR 1806–20] changed our ionosphere from night to day. Some fishermen in the arctic saw a sudden aurora at that moment.”
And get this: Magnetars are not powered by nuclear energy. “In magnetars,” Kaspi explains, “we see a unique source of power. All of its energy comes from the gradual loss of its magnetic field.”
The intense magnetism bends and deforms a magnetar’s solid crust to produce “starquakes.” These are nothing like the tremors we get here, which can merely destroy a city. No, a neutron star’s ultra-dense starquakes release titanic bursts of energy that actually create electrons and antimatter positrons. When those combine and annihilate each other, they produce the lethal gamma rays that sweep through the universe.
Meanwhile, the magnetism slows the star. In a mere 10,000 years, according to current thinking, the magnetic field weakens to a paltry 2 trillion times greater than Earth’s. Then, the starquakes stop and the gamma rays die out.
In short, magnetars embody the physics of extremes: density, gravity, and magnetism. No wonder they’re so much fun.
Fun, that is, as long as we keep our distance. Imagine a future astronaut approaching SGR 1806–20. When half as far as the Earth-Moon distance, it would still look like a harmless dot, but all of the astronaut’s credit cards would suddenly be erased. He’s now broke, but curiosity still drives him forward. At 2,000 miles (3,000km), the magnetar still appears as just a pinpoint, but its magnetism now pulls every atom in the astronaut’s body into long, strange, needle formations.
The trip is over. It was a fatal attraction.