What Exactly Does A Magnetar Do?

We'll never see a magnetar in our lifetimes - but we know they’re out there

magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field.
Photo credit: NASA
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By Kevin Roeten:

How Does A Magnetar Develop?

A sub-type of neutron star, a “magnetar,” is something no one will ever see. But we know they’re out there—larger, more massive, and something more different than anything we’ve seen before. When a massive star dies, its core collapses under its own gravity into a black hole. One has to remember this infinitely dense point in space is where the normal laws of physics no longer apply.

The other option for a dying giant is the transformation into a neutron star. That’s when physics is put on its head. In real-time astronomers are viewing an entity billions of light years away. Detection is possible because this entity is radiating the energy of hundreds-of-billions of suns. With that output, the object is a little larger than 10 miles, and astronomers are not entirely sure what this object is.

Recently Science has reported it could be a giant magnetar—a very rare type of star. But in a discipline regularly using gigantic numbers to express size, the case of this powerful object is so extreme, Krzysztof Stanek of Ohio State University got downright ‘apoplectic’ describing it. The reaction in this specific magnetar is so powerful, it eliminated any energy limits placed by physics.

Astronomers have called this possible supernova ASASSN-15lh (pronounced “assassin”), and noted its existence when it first flared to life in 2015 to observers. Only two dozen magnetars exist as we know today. Like all neutron stars, magnetars form as a result of a core-collapse supernova, making a star about 20 km in diameter, with a mass of the Sun.

To Close To Handle

The actual distance to ‘assassin’ makes the object unable to be seen with the naked eye, because it’s 3.8 billion light years away. Per Stanek, “If it really is a magnetar, it’s as if nature took everything we know about magnetars and turned it up to 11,”  basically translating to “11 on a scale of 1 to 10.” A magnetar (contraction of magnetic star) is a neutron star with an ultra-strong magnetic field. In this case—approximately ~1015 gauss. The ‘gauss’ is the[centimeter-gram-second] unit of magnetic induction—for a correct answer on Jeopardy.

This field is a thousand-trillion times stronger than Earth’s, making it the most magnetic object known. The strongest magnet on Earth is only one tesla, and a magnetar is 100billion times that.

ASSASSIN has discovered 250 supernovae since 2014. It was determined the explosion powering ASASSN-15lh had a sheer magnitude 200x greater than the average supernova, 570 billion times brighter than the Sun, and 20x brighter than all the stars in the Milky Way combined.

“We have to ask, how is that even possible?” said Stanek, professor of astronomy at Ohio State. “It takes a lot of energy to shine that bright, and that energy has to come from somewhere.” Right now, no one knows what the power source could be for ASASSN-15lh.

Effects Of Actual Magnetar

If a rogue magnetar were to fly past us, it would lift metal objects off the Earth from 100,000 miles away. Coming within 10,000 miles, its magnetism would stop the electrical nerve impulses of every living person, stopping our heart. And grazing us at 1,000 miles, it would rip all of the iron out of our bloodstreams. We’re lucky the closest magnetar is 15,000 light-years away.

We only know of 10 magnetars in the Milky Way Galaxy. Each magnetar powers an explosion brighter than the Milky Way itself. The Rossi X-ray Timing Explorer, RXTE, launched in 1995 from Kennedy Space Center, was designed to observe neutron stars, X-ray pulsars, and X-rays. Using RXTE, astronomers study how gravity works near black holes, and observe changes in X-ray brightness lasting a thousandth of a second, or for several years.

A neutron star (and specifically a magnetar) generates a gravitational pull so powerful, a marshmallow impacting the star’s surface would hit with the force of a thousand hydrogen bombs. Magnetars, the most magnetic stars known, aren’t powered by a conventional mechanism such as nuclear fusion or rotation,” per Dr. Vicky Kaspi.

Magnetars not only push the envelope, but rip it apart, possibly sending it to another dimension, and represents a new way for starlight to appear. The discovery of a magnetar’s former companion elsewhere in a cluster, may answer how a star starting off so massive could become a magnetar, rather than collapse into a black hole.

Although not totally understood yet, magnetars have magnetic fields a thousand times stronger than ordinary neutron stars measuring a million-billion Gauss. Our Sun’s magnetic field is only about 5 Gauss.

In Cassiopeia, 18,000 light-years from Earth, a Magnetar [1E-2259] is being watched. It suddenly began bursting in 2002, with 80 bursts over a 4-hour window. Since then, it has not been seen.

‘Starquakes’

Observationally, magnetars appear as Soft-Gamma Repeaters, SGRs, or Anomalous X-ray Pulsars, AXPs. Like all neutron stars, magnetars form as a result of a core-collapse supernova, and have a mass equal to the Sun. Magnetars get their incredibly strong fields from a dynamo requiring a very fast rotation for this mechanism.

Magnetars were discovered in 1979, when a powerful blast of gamma rays even sent detectors off the charts, producing changes in the Earth’s upper atmosphere.

Because the outer shells of neutron stars are so rigid, they crack under the stresses caused by magnetars’ intense interior force fields. These ruptures are called “starquakes,” and they’re similar to earthquakes from violent seismic reconfigurations of the crust. “Starquakes” shift the crust just a fraction of an inch, triggering an enormous magnetically powered explosion. The luminous bursts of radiation discharged by these quakes can be seen across the galaxy.

Collision Klaxon Already Screaming

The Andromeda Galaxy is approaching the Milky Way at 68 miles/second. In 2012, researchers concluded this collision is definite, after using the Hubble Space Telescope to track the motion of Andromeda between 2002 and 2010.[1]Andromeda’s tangential or side-ways velocity with respect to the Milky Way was found to be relatively much smaller than the approaching velocity and therefore it is expected to directly collide with the Milky Way in 3.7 billion years.

Even with only 12 known magnetars in this galaxy’s existence, how many unseen ones exist? How many exist in other galaxies, such as Andromeda? And how many may alter orbits when Andromeda passes though the Milky Way in a couple of billion years?

Will any magnetars make close passes to earth in the next few eons? If they do, we’ll literally be edible toast.

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Kevin Roeten can be reached at roetenks@charter.net.

© Copyright by Kevin Roeten, 2016. All rights reserved.

Kevin Roeten
About Kevin Roeten 168 Articles
CHO's science editor Kevin Roeten is a former Chemical Engineer. He enjoys riding the third rail of journalism: politics and religion. As an orthodox Catholic, Roeten appreciates the juxtaposition of the two supposedly incompatible subjects.   Kevin is a Guest Columnist for the Asheville Citizen-Times, and the Independent (Ohio), and writes for numerous blogs (Nolan Chart, Allvoices) and newspapers, including USA Today.   A collaborator in the book Americans on Politics, Policy, and Pop Culture (Jason Wright and Aaron Lee), he is also an amateur astronomer, and delves into scientific topics.   Kevin Roeten can be reached at roetenks@charter.net.