Podcaster: Richard Drumm
Title: Space Scoop: Cosmic Magnet Mystery Solved?
Organization: Astrosphere New Media
Link : astrosphere.org ; http://unawe.org/kids/unawe1419/
Description: Space scoop, news for children.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is 365 Days of Astronomy. Today we bring you a new episode in our Space Scoop Series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
An artist has drawn this picture of a distant magnetar to give us an idea what it would look like close-up. The star is extremely hot and compact, which is why it would glow this bright blue-white colour. You wouldn’t actually see the funky arcs coming out of the star, these are supposed to emphasise the star’s ultra-strong magnetic field. However, in reality, magnetic fields are invisible. Credit: ESO/L. Calçada
The Universe is immeasurably large and filled with countless weird and wonderful objects, so it’s not surprising that we’re discovering new things about it all the time.
But some new discoveries are more exciting than others – like last month’s discovery which might solve a 35-year-old mystery: how magnetars form. And also a newer mystery: the mystery of the solitary magnetar.
With the death of every star comes the creation of a new and exotic object. The type of object depends on the size of the original star.
For example, when our Sun runs out of fuel, it’ll become a planetary nebula, one of the prettiest things in the galaxy! Do a Google/Images search, you’ll see!
When a 10 to 20ish solar mass star runs out of juice, it forms a neutron star, where the star basically becomes a giant (well, city sized, 20 km across) ball of neutrons, with the neutrons in the center actually touching each other, not held apart by nuclear forces like in ordinary matter.
And when you have a star more than 30 times as massive as the Sun reaches the end of its life, it becomes a black hole, where the matter collapses down to an infinitely small point or “singularity” where the gravity field is so intense even light cannot escape.
But three years ago, ESO astronomers stumbled across the remains of a star 40 times more massive than the Sun and what they found wasn’t a black hole, it was a magnetar.
Now magnetars are bizarre objects even by astronomical standards, often breaking records in terms of size and density – like neutron stars they are no larger than a city, but more massive than the Sun.
They also spin incredibly quickly and are a astonishingly strong magnets! Even stranger than a magnetar though, is a magnetar that’s off on its own. Magnetars are formed by interactions between two stars, meaning they need a companion to exist. Kinda sounds like Dr. Who, dunnit?
But this magnetar was found floating in space all on its own. Well astronomers believe that just before some massive stars evolve into a black hole, a companion star steals away some of its material.
The companion eats enough of the star that it is no longer massive enough to form a black hole when it eventually explodes, and a magnetar is formed instead of a black hole.
Astronomers believed that a star aided the creation of this mysterious magnetar before being ejected from the area by a cosmic blast, when the magnetar exploded.
So, a search began for the runaway companion star.
Last month, after many years of searching, astronomers have announced that they’ve caught the culprit fleeing the scene!
By locating this star, called Westerlund 1 W 5, astronomers now have even more evidence supporting their theory of how magnetars form.
Here’s how it goes: In the first stage of this process, the more massive star of the pair begins to run out of fuel, becomes a red giant & transfers its outer layers to its less massive companion — which is the one destined to become the magnetar — causing it to rotate more and more quickly.
This rapid rotation appears to be the essential ingredient in the formation of the magnetar’s ultra-strong magnetic field.
In the second stage, as a result of this mass transfer, the companion itself becomes so massive that it in turn sheds a large amount of its recently gained mass.
Now much of this mass is lost to the cosmos but some is passed back to the original star,the star that we still see shining today as Westerlund 1 W 5.
So it seems that being part of a double star system may be an essential ingredient in the recipe for cooking up a magnetar.
The rapid rotation created by that mass transfer between the two stars appears necessary to generate the ultra-strong magnetic field and then a second mass transfer phase allows the magnetar-to-be to slim down just enough so that it doesn’t collapse into a black hole at the moment of its death.
Cool Fact: Magnetars are the strongest magnets in the Universe. Wicked strong. Insanely strong. If there was a magnetar half the Moon’s distance away from Earth, it would wipe clean the magnetic stripes of every credit card on the planet!
And you could finally forget all about those old VHS tapes of yours!
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