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Process of heavy elements sinking tto the center of stars



 
 
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  #1  
Old February 14th 10, 02:29 AM posted to sci.physics,sci.astro
BURT
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Default Process of heavy elements sinking tto the center of stars

They then fuse more under the maximum pressure. This reveals that they
get even heavier while near the cores of stars.


Mitch Raemsch

  #2  
Old February 14th 10, 02:54 AM posted to sci.physics,sci.astro
dlzc
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Default Process of heavy elements sinking tto the center of stars

On Feb 13, 6:29*pm, BURT wrote:
They then fuse more under the maximum pressure.
This reveals that they get even heavier while near the
cores of stars.


Heavy nucleii are easier to buoy, due to their larger net charge.
http://en.wikipedia.org/wiki/Brazil_nut_effect

I'd expect the heavier elements to stay near the surface... until the
star begins to cool.

David A. Smith
  #3  
Old February 14th 10, 05:06 AM posted to sci.physics,sci.astro
BURT
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Posts: 371
Default Process of heavy elements sinking tto the center of stars

On Feb 13, 5:54*pm, dlzc wrote:
On Feb 13, 6:29*pm, BURT wrote:

They then fuse more under the maximum pressure.
This reveals that they get even heavier while near the
cores of stars.


Heavy nucleii are easier to buoy, due to their larger net charge.http://en.wikipedia.org/wiki/Brazil_nut_effect


That is the opposite. Heavy elements sink.

I'd expect the heavier elements to stay near the surface... until the
star begins to cool.

David A. Smith


Protons never attract electrons. If they did they would come together.

Mitch Raemsch
  #4  
Old February 14th 10, 04:02 PM posted to sci.physics,sci.astro
bert
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Posts: 1,997
Default Process of heavy elements sinking tto the center of stars

On Feb 13, 11:06*pm, BURT wrote:
On Feb 13, 5:54*pm, dlzc wrote:

On Feb 13, 6:29*pm, BURT wrote:


They then fuse more under the maximum pressure.
This reveals that they get even heavier while near the
cores of stars.


Heavy nucleii are easier to buoy, due to their larger net charge.http://en.wikipedia.org/wiki/Brazil_nut_effect


That is the opposite. Heavy elements sink.

I'd expect the heavier elements to stay near the surface... until the
star begins to cool.


David A. Smith


Protons never attract electrons. If they did they would come together.

Mitch Raemsch


Mich Positive protons attract negative electrons. Your posts are
getting to be a joke. TreBert
  #5  
Old February 14th 10, 08:37 PM posted to sci.physics,sci.astro
BURT
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Posts: 371
Default Process of heavy elements sinking tto the center of stars

On Feb 14, 7:02*am, bert wrote:
On Feb 13, 11:06*pm, BURT wrote:





On Feb 13, 5:54*pm, dlzc wrote:


On Feb 13, 6:29*pm, BURT wrote:


They then fuse more under the maximum pressure.
This reveals that they get even heavier while near the
cores of stars.


Heavy nucleii are easier to buoy, due to their larger net charge.http://en.wikipedia.org/wiki/Brazil_nut_effect


That is the opposite. Heavy elements sink.


I'd expect the heavier elements to stay near the surface... until the
star begins to cool.


David A. Smith


Protons never attract electrons. If they did they would come together.


Mitch Raemsch


Mich Positive protons attract negative electrons. Your posts are
getting to be a joke. *TreBert- Hide quoted text -

- Show quoted text -


But opposites electric attract. How come the proton doesn't come
together with the electron?

Mitch Raemsch
  #6  
Old February 18th 10, 02:53 PM posted to sci.physics,sci.astro
Yousuf Khan[_2_]
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Posts: 1,692
Default Process of heavy elements sinking tto the center of stars

dlzc wrote:
On Feb 13, 6:29 pm, BURT wrote:
They then fuse more under the maximum pressure.
This reveals that they get even heavier while near the
cores of stars.


Heavy nucleii are easier to buoy, due to their larger net charge.
http://en.wikipedia.org/wiki/Brazil_nut_effect

I'd expect the heavier elements to stay near the surface... until the
star begins to cool.


You've got to be joking here. I can't see this effect being applicable
to nuclear physics, in the least. Maybe in a chemical process it would
work. They mention that the majority of the Uranium found at the surface
of the Earth is there because Uranium reacts with Oxygen to form a
compound that is less dense, therefore able to float to the surface.

Yousuf Khan
  #7  
Old February 18th 10, 02:57 PM posted to sci.physics,sci.astro
Yousuf Khan[_2_]
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Posts: 1,692
Default Process of heavy elements sinking tto the center of stars

BURT wrote:
But opposites electric attract. How come the proton doesn't come
together with the electron?



Happens in neutron stars, due to gravity. But without gravity as the
overwhelming force, the only thing attracting the two are the
electromagnetic force, since the Strong nuclear force doesn't act on
electrons. The electromagnetic isn't strong enough to overcome and
contain their quantum movement.

Yousuf Khan
  #8  
Old February 18th 10, 07:32 PM posted to sci.physics,sci.astro
dlzc
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Posts: 1,426
Default Process of heavy elements sinking tto the center of stars

Dear Yousuf Khan:

On Feb 18, 6:53*am, Yousuf Khan wrote:
dlzc wrote:
On Feb 13, 6:29 pm, BURT wrote:
They then fuse more under the maximum pressure.
This reveals that they get even heavier while near the
cores of stars.


Heavy nucleii are easier to buoy, due to their larger
net charge.
http://en.wikipedia.org/wiki/Brazil_nut_effect


I'd expect the heavier elements to stay near the
surface... until the star begins to cool.


You've got to be joking here.


I'm not.

I can't see this effect being applicable to nuclear
physics, in the least.


It has nothing to do with nuclear physics, but to do with an ion with
lots of positive charges (large "size") and a reluctance to quick
speed changes (large mass).

Maybe in a chemical process it would work.


Or just in a physical "vibratory" environment.

They mention that the majority of the Uranium found
at the surface of the Earth is there because Uranium
reacts with Oxygen to form a compound that is less
dense, therefore able to float to the surface.


I would expect that for even negligible convection rates, the heavier
stuff... once off-center, would continue to migrate to a star's
surface. We don't expect our Sun to have *any significant* convection
from near its core, but it may if it cools or heats "rapidly". And so
I expect there may be a concentration of heavy stuff near the center,
but I'd expect anything much different than helium to be lofted
outwards, ASAP, and the heavier the faster.

David A. Smith
  #9  
Old February 22nd 10, 10:35 PM posted to sci.physics,sci.astro
Steve Willner
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Posts: 1,172
Default Process of heavy elements sinking tto the center of stars

In article ,
dlzc writes:
Heavy nucleii are easier to buoy, due to their larger net charge.
http://en.wikipedia.org/wiki/Brazil_nut_effect
I'd expect the heavier elements to stay near the surface... until the
star begins to cool.


What applies to Brazil nuts doesn't necessarily apply to stars.

Stellar interiors are generally convective or fully ionized, often
both. If there's convection, everything is fully mixed throughout
the convective zone. If fully ionized, there's no size difference
for the "Brazil nut effect" to operate on. Heavy nuclei will tend to
sink, but the sinking is a diffusion process with very small mean
free path, so the time scale is very long indeed. (I think it's
longer than a Hubble time but could be wrong about that; anyway it's
billions of years.)

Even if you can find a zone in some star that's both non-convective
and not fully ionized, heavy elements won't float. The "radius" of
an atom goes quadratically as the shell number and inversely as the
nuclear charge squared. (This is a very rough semi-classical
approximation but adequate for the present discussion.) So carbon,
for example, has an "atomic density" 36/8 times that of hydrogen,
even when the carbon is neutral. This is quite enough density
difference to make heavy atoms tend to sink, but as mentioned above,
the time scale is very long indeed.

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Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
 




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