Saturday, September 1, 2012

The Magnetar: King of the Neutron Stars


My other blogs are:

A neutron star with a gigantic magnetic field is known as a magnetar, where even at a distance from Earth to Moon a human's flesh would be ripped apart from the magnetism
 
GENERAL LIMITS OF UNIVERSE- Have you ever wondered about what could be more amazing than the things we already know in astronomy? Such as what could be hotter than a blue supergiant? Or both as dense and hot as a neutron star? Or what could spin faster than a pulsar? Or as you all already know, what could cause more gravity than a black hole? For example, we all know that gravity is essentially limitless, which is an oddity since everything in the universe seems to have a discernible limit, like top speed (light speed) or maximum cold (absolute zero) or theoretical maximum mass since the universe has a finite amount of volume. I suppose everything is limited to the confines of the universe in one way or another. But in 1979 the first magnetar was discovered, which is also known as a Soft Gamma-ray Repeater (SGR) since it blasts gamma rays so often.
MAGNETISM OF EARTH VS MAN-MADE MAGNETS VS MAGNETAR - The magnetar is a neutron star with terrible magnetic fields just as a (millisecond) pulsar is unique in that it spins nearly at the speed of light. Just as little else has ever been seen quite so impressive as a pulsar spinning or like a black hole devouring, no other object has really been observed with magnetic forces quite so impressive as the magnetar. Only 10 of these unusual objects have been discovered, and with a magnetic field strength of 100 billion teslas, a magnetar's magnetic field makes the Earth's magnetic field strength of ~0.00006 teslas look like a refrigerator magnet, which is actually not even the power of a common fridge magnet come to think about it! Even the world's most powerful magnet makes the Earth look pathetic, where the National High Magnetic Field Laboratory in Tallahassee built the world's most powerful magnet weighing about 34 tons and being 22 ft. tall has a magnetic field of 45 teslas, which is about a million times (106) more powerful than the Earth's magnetic field (The World's Most Powerful Magnet - Popular Mechanics)
THE MAGNETAR- Those human-made magnets are a feat of engineering, yet the magnetic fields of magnetars are hundreds of millions of times stronger than any man-made magnet and quadrillions (1015) of times more powerful than the field surrounding Earth.
The Earths magnetic field, which deflects compass needles measured at the N magnetic pole 0.6 Gauss
A common, hand-held magnet like those used to stick papers on a refrigerator 100 Gauss
The magnetic field in strong sunspots (within dark, magnetized areas on the solar surface) 4000 Gauss
The strongest, sustained (i.e., steady) magnetic fields achieved so far in the laboratory generated by hulking huge electromagnets 4.5 X 105 Gauss (45 tesla)
The strongest man-made fields ever achieved, if only briefly made using focused explosive charges; lasted only 4 - 8 microseconds. 107 Gauss
The strongest fields ever detected on non-neutron stars found on a handful of strongly-magnetized, compact white dwarf stars. (Such stars are rare. Only 3% of white dwarfs have Mega-gauss or stronger fields.) 108 Gauss
Typical surface, polar magnetic fields of radio pulsars the most familiar kind of neutron star; more than a thousand are known to astronomers 1012-1013 Gauss
Magnetars soft gamma repeaters and anomalous X-ray pulsars
(These are surface, polar fields. Magnetar interior fields may range up to 1016 Gauss, with field lines probably wrapped in a toroidal, or donut geometry inside the star.)
1014-1015 Gauss
(10-100 gigatesla)
MAGNETARS, NEUTRON STARS AND PULSARS- The magnetic field of the magnetar eventually decays, emitting high-energy electromagnetic radiation, particularly X-rays and gamma rays. Its bursts pump out more energy than the Sun does in 1,000 years, while most other stars like neutron stars pump out more energy a day than the Sun does in a year, making magnetars the king of neutron stars. Now magnetars are a type of neutron star just like pulsars are, but are differentiated from other neutron stars by their stronger magnetic fields. Just like neutron stars and pulsars, magnetars are also only about 12 miles in diameter and whose surfaces are well into the millions of degrees Fahrenheit. However, they all three differ in one way or another, for while a typical neutron star rotates fully in under a second, a pulsar rotates about 200-500x per second with the record breaking PSR J1748-2446ad pulsar spinning 716x per second. The magnetar, however, requires between 1-10 seconds simply to finish a single rotation, making it up to 1,000% slower than a typical neutron star's speed of rotation. And just as a regular neutron star is extremely dense, where a single thimbleful of neutronium (neutron star matter) can weigh 100,000,000 tons, pulsars and magnetars are thought to have the same characteristics. Overall, the densities and temperatures of neutron stars, pulsars and magnetars are in the same range since they are all limited in size and mass in order to be created in the first place, for if a star that goes supernova is more than 8x the Sun's mass, it is typically thought to be too massive to form the tight neutron center of a neutron star, therefore preventing its formation. And although theories are few and differ widely, it is most likely that pulsars and magnetars are all related to neutron stars, as all three stars are shaped the same, have the same overall size and density and also share the same basic temperature range. They are so similar, in fact, that many astronomers believe that they all represent a chain of the life of a star. For example:
-
-
-
Possible Birth of a Magnetar--
1) A star is born that is between 4-8x the mass of the Sun
2) The star lives its life and then dies, going supernova, and forms into a super-dense neutron star
3) The neutron star often has a companion orbiting star, and due to its own super-high gravitational attractions, it devours it slowly
4) As the neutron star devours its orbiting star companion, there is a chance the neutron star begins spinning due to the angles and orbit of the companion star, turning the neutron star into a pulsar
5) For various possible reasons, the pulsar suffers energy loss and eventually slows down in its near-light-speed spinning, giving birth to a magnetar. The pulsar's own untamable magnetic energies cause the metals on its outer crust to explode, resulting in the tell-tale gamma and x-ray bursts that indicate this particular pulsar is actually a magnetar
-
-
-
Unfortunately, astronomers could all be dead wrong about all three of these stars since virtually nothing is known about neutron stars, pulsars and magnetars except some basic methods of observation from light wavelengths, radio transmissions and other means of observation that are unfortunately, difficult to use and limited.
BUT HOW? While the machinations behind the magnetar are basically unknown, their magnetic field gives rise to very strong and characteristic bursts of X-rays and gamma rays, so even though they are extremely rare, when an astronomer finally comes across a magnetar, it's easy to tell what it is. Finding one though is just plain hard, either because they are so rare (just aren't many) or perhaps due to other factors, such as where it may be more common for one to form (globular star clusters are thought to be their formation grounds). Neutron stars are the only stars with a solid surface crust, which is about 6/10th's of a mile deep and covers a thick fluid of neutrons (neutronium) over either a superfluid or a solid core of subatomic particles. The star's surface probably has a chunk of metal like iron that is magnetizable, where this metal would feel a force equal to 150,000,000x the Earth's gravitational pull on it. This means that while the Earth has a 32.2 ft/s2 gravitational "pull," that's 4,830,000,000 ft/s2 for a magnetar. It is precisely those movements of that strong magnetic field on the crust that wrinkles the crust, causing star quakes that would be the source of the soft gamma-ray bursts. This is how we can even know from so far away that a magnetar differs even at all to other neutron stars- the magnetism causes cataclysmic quakes so powerful that the crust crinkles up with such force an explosion of light of many orders of magnitude greater luminosity than the star itself become visible at truly staggering distances. Isn't it enough that the star itself is millions of degrees, has more gravity than 8 Suns and shines brighter than most stars? Nope, that's not good enough for God and his grand creation. Magnetars simply must stand out even more, with explosions so bright that the star itself seems dim by comparison during the explosions of gamma and x rays.
-
However, they are still hard to find, for not only do we simply not know very much about them, the active life of a magnetar is very short, as their magnetic fields decay after about 10,000 years. Even if many live as long as the typical neutron star, their characteristic light bursts from their magnetic fields only last a very short while, making their unique light wavelengths only visible to telescopes for brief periods of time before their unique light fades.

No comments:

Post a Comment