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Accretion disc rigidity
How rigid might the accretion disk of a neutron star be? Rigid
enough to vibrate? |
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Accretion disc rigidity
On 2011-05-26, Frisbieinstein wrote:
How rigid might the accretion disk of a neutron star be? Rigid enough to vibrate? It's not a solid object. Bud |
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Accretion disc rigidity
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Accretion disc rigidity
Frisbieinstein wrote in news:2b05512c-5e69-4077-
: How rigid might the accretion disk of a neutron star be? Rigid enough to vibrate? In article 00, eric gisse writes: It is about as rigid as a cloud of plasma. Looks right to me. Which couls support some vibration modes but nothing that would not be damped out rather quickly. Why would p-waves or gravity waves necessarily be damped out quickly? (I wouldn't expect s-waves to exist.) I'd expect gravity waves to last at least a few rotations, and I vaguely recall some X-ray variability evidence to that effect. However, I don't study these objects and could be wrong (and my memory is not very trustworthy in any case, alas). -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Accretion disc rigidity
In article 00,
eric gisse writes: I just noticed that I missed something obvious. Since when do neutron stars support accretion disks? Aren't a lot of X-ray binaries accretion disks around neutron stars? SW Why would p-waves or gravity waves necessarily be damped out quickly? I believe my guess at the time was that the turbulence of the medium coupled with its' relative low density makes it hard to support waves that could propagate for meaningful stretches. Turbulence might be a problem, but I'm not sure low density is. Plasmas are pretty well coupled because of the charges. (By the way, possessive pronouns don't have apostrophes, though sometimes I put them in by accident myself.) SW I vaguely recall some X-ray variability evidence... It had to do with near-periodic X-ray variability, but I don't remember the circumstances or reference and may be mistaken about the whole thing. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Accretion disc rigidity
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Accretion disc rigidity
In article 00,
eric gisse writes: I know that binary systems with a neutron star and a regular star at close orbital distances can result in matter being stripped off the star and thrown onto the surface of the neutron star. Neutron star X-ray binaries are pretty common. Cygnus X-2 is one famous example. The X-rays come from an accretion disk. ... high frequency oscillations will be radiated away or straight up absorbed via turbulence, considering the nature of an accretion disk. I think the part about turbulence is right, though I'm not sure "absorbed" is quite the right word. I don't see how waves in plasma can be "radiated away," though, whether the restoring force is pressure or gravity. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Accretion disc rigidity
"Steve Willner" wrote in message ... | In article 00, | eric gisse writes: | I know that binary systems with a neutron star and a regular star at | close orbital distances can result in matter being stripped off the star | and thrown onto the surface of the neutron star. | | Neutron star X-ray binaries are pretty common. Cygnus X-2 is one | famous example. The X-rays come from an accretion disk. Chocolate eggs are pretty common. Cadbury's Roses is one famous example. The eggs come from the Easter Bunny. Nunquam ponenda est pluralitas sine necessitate (Pluralities ought not be posited without necessity) - William of Occam, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi |
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