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Palomar

Member

From: USA

Registered: 2002-05-30

Posts: 9,734

Re: Fastest Possible Rotation?

*Hi-ho, me again.

I read in Scientific American:  The Secret Lives of Stars, Special Edition magazine that the Crab Nebula's pulsar rotates an astonishing once every 33 milliseconds.

I did double-check that statement.

So what is theoretically the fastest something can rotate without flying apart?  Probably depends on what it's made of, but just thought I'd ask "in general" (and in reference to celestial bodies).

Any answers or speculations would be appreciated, and thanks in advance.

--Cindy

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We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...

--John Sladek (The New Apocrypha)

GraemeSkinner

Member

From: Eden Hall, Cumbria

Registered: 2004-02-20

Posts: 563

Website

Re: Fastest Possible Rotation?

http://sphericalcube.com/thesis/thesisse2.php]LINK

The above may be a bit heavy on maths, sorry, but basically it depends on the stars radius as to how fast it can rotate before flying apart (it also depends on its gravity).

Graeme

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There was a young lady named Bright.
Whose speed was far faster than light;
She set out one day
in a relative way
And returned on the previous night.
--Arthur Buller--

flashgordon

Member

Registered: 2003-01-21

Posts: 314

Re: Fastest Possible Rotation?

i don't know about newtron stars, but for black holes, if they rotate above a certain speed limit, they give off gravitational waves.

Mad Grad Student

Member

From: Phoenix, Arizona, North Americ

Registered: 2003-11-09

Posts: 498

Website

Re: Fastest Possible Rotation?

Let's see. According to the artificial gravity equation given in The Case for Mars, F= (0.0011)w^2r, where F is centrifugal force in g's, w is the spin rate in rpm, and r is the radius of the object in meters, this pulsar would create a centrifugal force of 14,256,000 (!) g's at its equator assuming that its 8 kilometers in diameter. That's big . However, IIRC many neutron stars can produce over a billion times Earth's gravity, so that force would barely even cause the star to bulge even at its equator.

It would be very, very difficult to break apart a neutron star. A neutron star is essentially what happens when gravity becomes so ridiculously huge in an area that the very atomic structure of the matter involved is ripped apart and the whole thing acts like one giant atom, if my understanding of neutron stars is correct. The atoms of such a star are so tightly bound to each other that the only thing that can tear apart a neutron star (a rule of thumb in the universe is that there's always something that can rip, shread, or blow anything up) is another one, during a neutron star merger. That's such a ludicrously violent event that these mergers give off gamma ray bursts that can outshine the entire rest of the universe for a second or two. Is this a cool universe or what?

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A mind is like a parachute- it works best when open.

MarsDog

Member

From: vancouver canada

Registered: 2004-03-24

Posts: 852

Re: Fastest Possible Rotation?

while searching
http://www.google.com/search?q=Rotating … =]Rotating Hairy Black Holes

I found some
http://archive.ncsa.uiuc.edu/Cyberia/Nu … tml]movies.

http://home.earthlink.net/~djmp/Wheeler.html]Spacetime tells matter how to move. Matter tells spacetime how to curve