Saturday, February 17, 2007

Latest Spin on Neutron Stars


I hope everyone had a happy St. Valentine's Day. The afternoon was spent huddling together by the ocean watching the sunset. The Sun is fascinating to contemplate. Though our lives depend on it, humans know shockingly little about how the sun works. We should remember on Valentine's Day how important the heart is.

In Larry Niven's story, Beowulf Schaeffer rides a spacecraft to the vicinity of a NEUTRON STAR. These stars are the created in the aftermath of huge supernovae. As this month's ASTRONOMY magazine reports, even the energy source of supernova explosions is a mystery! Neutron stars are dense enough to make atoms collapse, so their outer layers are composed of pure neutrons. A cubic centimetre of neutron star would weigh a hundred million tons. They are denser than any object except for a Black Hole, which should be clue #1.

As reported by SPACE.com, astronomers using the ESA INTEGRAL satellite have found that neutron star XTE J1739-285 spins at 1,122 revolutions per second. The neutron star drains materiel from a companion object, giving off X-rays that astronomers can measure. XTE J1739-285 spins faster than any known neutron star, and faster than any object save for a Black Hole. This ought to be clue #2.

Some neutron stars are pulsars, emitting spinning beams of radiation like a lighthouse. The first pulsar was discovered by astronomer Jocelyn Bell in 1967. Being a woman, she was denied proper credit for her discovery. The beams spin because the axis of the source is independent of the neutron star's spin axis. As Dr. Roger Blandford noted last week, the source of these coherent beams has been a complete mystery. Something hidden within creates the twin beams. This should be clue #3.

Recently some neutron stars have been discovered to be magnetars. Their magnetic fields are so powerful that astronomers aren't sure how strong they get. They are more powerful than the magnetic field of any object except a Black Hole. Do we have enough clues, Scooby Gang?

The birth of stars, including our Sun, is triggered when tiny singularities collide with gas clouds. The clouds contain the elements for stars, but cannot turn into stars on their own. Presence of singularities causes the clouds to collapse until nuclear fusion is ignited. Outward radiation pressure balances gravity's inward pull to create an equilibrium that can last billions of years. A Black Hole can comfortably exist in the second-last place humans would look for one, inside the Sun.

Only occasionally do Black Holes reveal their presence. When a star of greater than 1.4 solar masses uses up all its fuel, the equilibrium between radiation and gravity is abruptly broken. The star collapses at nearly one quarter of the speed of light into the singularity. This sudden infusion of mass produces a titanic explosion, a supernova.

In the aftermath of a supernova, only the most dense of materiels survive. Superdense neutrons form an outer layer. The heart of a neutron star is a Black Hole. If the Black Hole has enough spin, it produces a magnetic field and twin jets exactly as observed. The Black Hole spins independently of the outer neutron layers, emitting the spinning beams of a pulsar.

Lack of a Black Hole explains why humans have been unable to recreate conditions inside the Sun for any length of time. Nuclear fusion has been reproduced only for brief moments, as in a hydrogen bomb. Containing a stable reaction requires the attractive force of a Black Hole. If humans understood this simple principle, energy generation would not be a problem. Scientists should learn from Luke Skywalker, push the computer away and follow the heart.

11 Comments:

Anonymous Darnell Clayton said...

That was a powerful (yet simple) explanation of not only how a star forms, but also the similarities and differences of a black hole and a neutron star.

You should consider writing a book about this stuff (how about The Universe for Dummies, if it is not already taken).

12:25 PM  
Blogger L. Riofrio said...

Thank you darnell. I have recently written a book about this stuff, but publishing something out of mainstream is a long process. I am glad you enjoyed the writing.

9:09 PM  
Anonymous a quantum diaries survivor said...

Hi Louise,

I read Niven's short story... I remember an introduction by Isaac Asimov about it, playfully ranting that he could have written the same story (which won Niven a Hugo prize for SF) if he had thought in terms of a story what he wrote as an essay on neutron stars...

Good luck with your book!

Cheers,
T.

2:56 AM  
Blogger The Swine said...

Being that my I.Q. and my shoe size are quite similar, I am amazed at your ability to make such lofty subjects so understandable! Keep up the great work! Oh, and if you have an extra black hole, can I borrow it? I have a lot of junk to get rid of.

3:32 PM  
Blogger Kea said...

I hope the publishing process is at least moving in the right direction ...

2:09 PM  
Blogger mark said...

hi Louise: how can the spin of the "source" (the black hole at the center?) be different from the axis of the spin of the neutron star itself? I'd think (for what that's worth!) that the spins would eventually match.

2:34 PM  
Blogger L. Riofrio said...

Thanks Kea, the news is getting better. I appreciate the efforts you and others have made and won't disappoint you.

Thank you sw, that gives us all hope to break through.

Mark, since the Black Hole is surrounded by radiation it is essentially friction-free inside the star. It can change direction independent of the star.

4:52 PM  
Blogger CarlBrannen said...

Louise; Great to hear you're working on a book. Is it in LaTex? I'll show you mine even if you won't show me yours.

8:27 PM  
Blogger Greg said...

please understand that I am working from a basic college physics class and a layman's interest in astronomy and astrophysics fed by a steady diet of books and the Science Channel, but wouldn't a singularity, even a small one emit the typical signature radiations of a black hole, namely Hawking radiation and x-rays? Or would the sheer mass of a star "swamp" the signal so to speak? And would the Earth's mass be able to do the same thing?

Also, I think I understand the basics of what you are getting at, but how would you explain a world that is geologically dead like Mars or Mercury?

8:58 AM  
Anonymous Carl Brannen said...

Louise; as you may know, I suspect that there are two natural speeds, c and c\sqrt{3}, with only Planck energy particles moving at the higher speed. It turns out that this sort of thing may have something to do with how black holes violate entropy. See hep-th/0702124

11:55 AM  
Blogger L. Riofrio said...

Carl, my book is in .doc and may get some good news soon. I have enjoyed your writings too.

Welcome to you, Greg. Radiation from a Black Hole inside the Sun would make a small contribution to the stars total energy output. In the case of Earth, the radiation eventually makes its way to the surface as geologic heat.

Not all objects would contain singularities. Mars shows indications of liquid water and a magnetic field in the past. It may have contained a Black Hole which has since evaporated.

A Black Hole would explain why little Mercury is so dense with a strong magnetic field. It would also cause Mercury to have internal heat, which the MESSENGER spacecraft may confirm in 2011. So far only ONE spacecraft has made a brief flyby of the planet, so very little is known about Mercury. Quoting Monty Python, Mercury would say, "I'm not dead yet!"

12:14 PM  

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