The Strange Life of Magnetars
Dead stars find new life as cosmic powerhouses
They’re tiny, yet they are the true powerhouses of the universe: Magnetars are the remnants of stellar explosions, and they contain an unimaginable amount of power. That’s why many researchers no longer regard magnetars as merely fascinating, but also a potential menace to mankind…
HUGE RAY GUN
When the magnetic field of a magnetar collapses, an earthquake-like discharge of energy is the result. This gives rise to gamma-ray bursts, which could be dangerous to the Earth.
For life on the Earth, it was an apocalypse: 65 million years ago a meteor the size of a truck crashed into Mexico. In one stroke, around 70% of the life on our planet was wiped out. It lead to the end of the dinosaurs, and for evolution it was a terrible case of déjà vu. That’s because the disaster was the fifth major mass extinction to happen within 500 million years. Previously many scientists thought there was one main trigger of such epochal events in Earth’s history: meteorite impacts. Now, however, they’ve encountered a phenomenon that could eclipse even the largest meteorite: magnetars—disfigured star corpses lurking in the depths of space that could strike at any time…
THE BIRTH OF A CORPSE
A star dies when it has run out of nuclear fuel, after which it breaks up under its own gravity. The result is a supernova—the biggest explosion in the universe, which releases more energy than our Sun can produce in 10 billion years. This process gives rise to a neutron star—an incredibly compressed piece of matter with a diameter of no more than 12 miles. Neutron stars themselves are not usually dangerous—9 out of 10 will become transformed into a pulsar, which does just one thing: It rotates extremely fast until all its remaining energy has been used up. However, not every neutron star leads such a peaceful existence. A small number of them mutate into an interstellar hothead—a magnetar!
They have “properties that cannot be understood in the laboratories on Earth,” says Dr. Michael Gabler of Germany’s Max Planck Institute for Astrophysics. If anything, the conditions inside a magnetar can only be calculated using complex models. And these reveal that a magnetar’s center is three times denser than an atomic nucleus. In fact, the interior of a magnetar is so dense that a piece of the neutron star the size of a sugar cube would weigh hundreds of millions of tons on Earth. Inside, the temperature is over 1.8 billion degrees Fahrenheit. In addition, a magnetar is perfectly smooth. Its gravity does not permit protrusions to form. If Mount Everest were deposited onto one of these rotating magnets, it would become compressed to the size of an ant.
CAN A MAGNET KILL ME?
The magnetic fields of these zombie stars are by far the strongest in the universe. On the surface they reach a field strength of several quadrillion gauss. In comparison, the magnetic field of our Sun has an intensity of around 1 gauss, while at the North Pole of Earth the value is 0.6 gauss. If a magnetar were to come within 125,000 miles of Earth, its magnetic field would be so strong that all of the magnetic stripes on credit cards would be erased in one fell swoop. A magnetar could attract an iron train on the Moon from a distance of 50,000 light-years. But what would happen if a magnetar approached Earth from the vicinity of the Moon?
A MAGNETAR AS FAR AWAY AS THE MOON WOULD DELETE ALL THE DATA FROM THE CREDIT CARD IN YOUR POCKET
Researchers give us the all- clear. To be sure, field strength of 1 billion gauss would immediately wipe out humanity, but, according to experts, it would never actually come to that. The reason: In order to reach such intensity, the magnetar would have to practically be in sight. But at this distance its magnetic force would be so strong that the structure of the atoms and molecules in our bodies would be rearranged—basically we wouldn’t die, we’d cease to exist.
HOW MANY APOCALYPSES HAS EARTH SURVIVED?
A much more realistic threat to Earth is posed by a magnetar’s indirect influence: Magnetars are actually deadly radiation cannons that fire huge gamma-ray bursts across the universe. No matter how far away it’s coming from—a single direct hit could mean the end of humanity. If such an immense jet of energy were to shoot through space, “We really wouldn’t want Earth to be in its way,” says University of Sydney physics professor Peter Tuthill.
Surprisingly, Earth has been shot at by these aggressive zombie stars dozens of times—even if they were ultimately only warning shots. One struck Earth on December 27, 2004. From 50,000 light- years away, the magnetar SGR 1806-20 fired its “ray gun” at our atmosphere. The result: The beam knocked out 15 satellites and longwave radio communication was massively disrupted. No one can tell if SGR 1806-20 is capable of doing even more damage. But this is neither the most obvious nor the largest magnetar in the Milky Way. That would be 1E 1048.1-5937 in the Carina constellation—a magnetar that’s a mere 8,800 light-years away from Earth. And then there’s CXOU J164710.2- 45516, which was found in the Westerlund 1 star cluster that is 16,000 light-years away. It’s still unclear how destructive a direct hit from a magnetar can be, especially one a lot larger and closer than the already destructive SGR 1806-20. According to statements made by University of Kansas astrophysicist Adrian Melott, it’s conceivable that an extremely powerful gamma-ray burst striking Earth could evaporate up to 25% of the ozone layer within a few seconds. “The oceanic food webs would collapse, agricultural crises and famines would develop. Perhaps it would even be the start of a new mass extinction,” says Melott. It wouldn’t be the first time…
ASTRONOMICAL DWARF Compared to other celestial bodies, magnetars are tiny— but their mass is all the greater. Just one teaspoon of a magnetar’s matter would weigh hundreds of millions of tons on Earth.
Max Planck Institute for Astrophysics