Twinkle, twinkle, little star, How I wonder what you are! Up above the world so high, Like a diamond in the sky.
I just could not resist the nursery rhymes. As kids in the kindergarten, we are already acquainted with the stars. It twinkles, and it is high above the earth.
A star is a luminous object filled with glowing gas or in a scientific terms globe of helium and hydrogen which through nuclear fusion produces energy that makes the gas glow.
Now that you know what a star is, have you heard of the magnetar?
Since we are discussing stars, using contextual clues, you may say it has something to do with magnet and star. Or a magnetic star. If you say that it is a magnetic star, then you are correct.
Wikipedia Creative Commons: An artist's impression of a magnetar
What is a Magnetar?
It is a special kind of neutron star that has one unmistaken attribute; they are dead stars and extremely magnetic. It is said to be the strongest magnet in the Universe.
Now we know what magnetars are, how did they come into being?
Birth of a Magnet
When a star reaches its lifespan's end, it explodes in a giving out a tremendous amount of luminosity. Talk about going out with a bang! At that point of its lifetime, it just briefly outshines any galaxies. Its radiation is even more than that of the sun in this brief farewell luminosity before fading away.
As the stars die, the outward light pressure counteracting the enormous gravity pull that is acting inward are gone. Since the counteracting force is gone, the significant inward force easily overwhelms the repulsive force that maintains the atoms collapse.
The effect is the electrons and protons are forced to become neutrons. Remember, I mentioned stars have glowing gas made up of hydrogen, helium, carbon, and iron. All are forced to be neutrons, and hence a star is born. It is known as a neutron star.
What have all these got to do with magnetar? You would see in a moment.
The former compressed star now, due to the conservation of angular motion, spins fast (hundreds of times per second).
Out of these neutron stars, some become magnetars. Scientists have not really figured out how that happens yet. But these special neutron stars is so dense that a teaspoon of its matter weighs billions of tons. That is not the only thing special about it, the magnetic fields of these magnetars are so big that it is as much as 1,000 trillion times that of the earth!
That is an immense amount of magnetic field which up till now is still a mystery waiting for scientists to unravel.
But there are theories of how they form. Scientists believe the two stars begin to die, orbiting same distance as the sun has the earth on its orbit, the bigger star loses some of its mass. This shed layer gets transferred to the smaller star making it rotate faster. This process continues as the smaller star has a massive gain. This second star also sheds some of its layers, some get transferred to the first, and a lot is scattered.
The smaller star (second star) is now huge and collapses in on itself creating a supernova that acts on the first star pushing it away. Due to the rapid rotation brought on by the dual-star process, this second star (supernovaed star) does not turn into a blackhole; rather it forms a magnetar with its powerful magnetic field.
About a Magnetic Star
The quest for magnetar had its beginning in 1979 after some gamma-ray disruption of atmosphere and some space equipment.These gamma rays were observed to be from the magnetar named SGR 0525-66 (soft gamma repeaters).
The strong magnetic field seen on a magnetar results to intense bursts of both gamma rays and x-rays.
But magnetars have a short lifespan of about 10,000 years. Then, the inactive magnetar ceases to send out any more bursts of these rays.
Ultimately, magnetars work by sending out extraordinarily powerful bursts of energy, but they don’t keep up such incredible power constantly; however, because they give off so much energy during these bursts, their lifespans are relatively short (around 10,000 years before they decay and are no longer magnetars).Source
There are about 29 magnetars, some other candidates are yet to be confirmed as magnetars out of about 2000 pulsars(a family of neutron stars) have been identified. But there are nearly a billion neutron stars that is in our Milky Way Galaxy.
The Fewer the Better
These few numbers of magnetars come as good news for our universe (Earth). The explosion of one magnetar (SGR 1806-20) in 2004 in a "starquake" caused a disaster as it destroyed satellites plus ionising the atmosphere on Dec 27, 2014 from its distance of 50,000 light years away!
The magnetic field of magnetars is tremendously powerful that any human within 600 miles of it would experience a dissemination of their molecular structure and nervous system.
But the good news is that it is light years away, and scientists have a job of discovering more of this mysterious but fascinating magnetic star.
References:
Neutron Stars, Pulsars and Magnetars
How Magnetars are Formed
Number of Magnetars
