why do neutron stars spin rapidly?

Answer 1

All stars start out with some spin. As a star changes from a regular one to a neutron star its diameter contracts as its density increases. Since the angular momentum must be conserved, the spin rate increases.

The standard example of speed increasing as radius decreases is the image of a figure skater pulling in her arms while spinning to increase her spin rate.

Answer 2

As many other answerers have pointed out, the reason is due to the conservation of angular momentum. Angular momentum is defined as the cross product between linear momentum, usually called p, and the distance r from the axis of rotation (e.g. L = p x r). Of course, for something like a star, you'd need to add up the angular momentum of all the particles in the star (mathematically, this is done with integrals, if you know anything about calculus).

So, a neutron star is basically a dead version of a star larger than our Sun. It's safe to say that, like our Sun, stars spin, just like the Earth spins about its axis. So, a star will have some amount of angular momentum (call it L0). Now, when a large star dies, the heat produced by nuclear reactions in its center stops being generated. This heat supports the weight of a star (think of how hot air balloons manage to expand and then float into the sky... it's kinda like that). Without this heat, there's nothing to hold the star up, nothing to keep it from falling in on itself due to its own gravity. A neutron star results when the star collapses enough that the pressure of neutrons can hold it up against the force of gravity (if the neutrons couldn't stop this, a black hole would result).

Now, say the star started out with a radius of 1 million miles. A neutron star is generally only, say, 10 miles across! So, the equation for angular momentum is L=p x r~mvr, where m is the mass involved, v is the speed of the mass, and r is the same r as above (the distance from the axis of rotation). Now, L has to remain the same (it's a law of physics...), so if r goes from 1000000 to 10, then v has to go from its starting speed to 100000 times its starting speed! Now the Sun rotates in about 10 hours or so. Thus, something rotating 100000 times faster than the Sun would rotate about three times each second!

That, in perhaps a bit technical wording, is why neutron stars spin so fast. If you don't understand this whole angular momentum thing, or how its conserved, someone else mentioned the idea of a spinning ballerina, but there's an evern better way of seeing it. If you find a chair that spins freely, get in the chair, and start it spinning it as fast as you can. Then try extending your arms and bringing them back close to your body, and see how it affects how fast you spin. With your arms close to your body, you should spin at least a little bit faster (note, however, that this can make you really dizzy, but it's still a lot of fun... :) ).

I hope that helps.

Answer 3

Neutron stars spin rapidly because they they are small in comparison to their mass. Basically, most neutron stars are no bigger than say.. Manhattan.. However, if you were to weigh just one sewer's thimble full of the densly packed neutrons comprising one of these stars it would weigh over 100 million tons. I realize that sounds crazy, but its incredible.

The scientific cause for the rapid rotation is conservation of energy and motion. It basically follows the same principals as an ice skater. When the skater pulls in their arms and stands tall, they spin faster. When they push their arms out, they slow down. Since the neutron star was once very large (still retains its mass, but decreases in size) it begins to spin faster and faster. This compresses the neutrons even more causing the immense weight I told you about earlier.

Answer 4

Neutron stars rotate extremely rapidly after their creation due to the conservation of angular momentum; like an ice skater pulling in his or her arms, the slow rotation of the original star's core speeds up as it shrinks. A newborn neutron star can rotate several times a second; sometimes, when they orbit a companion star and are able to accrete matter from it, they can increase this to several thousand times per second, distorting into an oblate spheroid shape despite their own immense gravity (an equatorial bulge).

Over time, neutron stars slow down because their rotating magnetic fields radiate energy; older neutron stars may take several seconds for each revolution.

The rate at which a neutron star slows down its rotation is usually constant and very small: the observed rates are between 10-10 and 10-21 second for each rotation. In other words, for a typical slow down rate of 10-15 seconds per rotation, then a neutron star now rotating in 1 second will rotate in 1.000003 seconds after a century, or 1.03 seconds after 1 million years.

Sometimes a neutron star will spin up or undergo a glitch: a rapid and unexpected increase of its rotation speed (of the same, extremely small scale as the constant slowing down). Glitches are thought to be the effect of a sudden coupling between the superfluid interior and the solid crust.

Neutron stars also have very intense magnetic fields—typically about 1012 times stronger than Earth's. Neutron stars may "pulse" due to particle acceleration near the magnetic poles, which are not aligned with the rotation axis of the star. Through mechanisms not yet entirely understood, these particles produce coherent beams of radio emission. External viewers see these beams as pulses of radiation whenever the magnetic pole sweeps past the line of sight. The pulses come at the same rate as the rotation of the neutron star, and thus, appear periodic. Neutron stars which emit such pulses are called pulsars.

You could get more information from the link below...

Answer 5

Because of the spin of the large normal star that collapsed to be a neutron star. The new neutron star is thousands of times smaller than the normal star it collapsed from, so it spins thousands of times faster, just like the spinning ice skater that spins faster by pulling her arms in closer.

Answer 6

Hi. They spin rapidly because they started out with a lot or rotational energy. Some slow down over time due to magnetic braking.

Answer 7

b/c they are small

recall the ballerina model to explain the conservation of angular momentum -- the 'smaller' she gets, the faster she spins

(of course my answer is only a first order approximation !!)

Answer 8

it is a dimensional transgression
at quantam phisics level the building blocks are strings of energy that vibrate and spin .the spinning of the neutron stars is a projected progression of that movement

Answer 9

They be Ridin' Spinners.

Answer 10

too much vodka? :)