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crust of neutron stars



 
 
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  #1  
Old August 7th 06, 06:42 AM posted to sci.astro
Allan Adler
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Posts: 40
Default crust of neutron stars


I read a recent article in Science News about how a certain neutron
star was shown to have a crust whose thickness is about 1/3 the radius
of the star. From this, the researchers concluded that the core really
consists of neutrons, not of other particles. This was based on certain
models.

Question 1: Where are these models described?

The article also said that the crust was made of iron.

Question 2: What state is this iron in?
Question 3: Is it pure iron?

Apart from the intrinsic interest in the star, as reported in the article,
I'm somewhat influenced by the recent reports on the ice continents,
methane seas and Earthlike weather (albeit colder) of Titan and I'm wondering
whether there could be much hotter places that could be described as having
seas, continents, weather and erosion. So, let's take this neutron star for
a moment.

Question 4: Are there variations in the thickness of the crust?
Question 5: Do neutrons bubble up through the crust?

Since it was hard enough for them to figure out that it has an iron
crust in the first place and to measure its thickness, I don't expect
that anyone necessarily knows the answers to these questions. But it is
interesting to speculate about it. At any rate, I'll be glad to know about
what is known about things like that.

Question 6: What is the density of the iron in the crust of the neutron star?

I'm not sure but I think I've heard about carbon stars and maybe oxygen
stars. I read in another issue of Science News that under sufficient pressure,
something like 100 Gigapascals, oxygen becomes a red superconducting metal.

Question 7: If there are oxygen stars, would one expect any of the oxygen to
be in that state?
--
Ignorantly,
Allan Adler
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.
  #2  
Old August 7th 06, 03:05 PM posted to sci.astro
jacob navia
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Posts: 341
Default crust of neutron stars

Allan Adler a écrit :
[snip]
Apart from the intrinsic interest in the star, as reported in the article,
I'm somewhat influenced by the recent reports on the ice continents,
methane seas and Earthlike weather (albeit colder) of Titan and I'm wondering
whether there could be much hotter places that could be described as having
seas, continents, weather and erosion.

[snip]

Look at this article in space.com
http://www.space.com/scienceastronom...ry_monday.html

There you find iron vapour condensing into iron rain in
dwarf stars... Really a NICE Weather... You go out to
take a walk and it rains molten iron.

Inconvenient, even your titanium umbrella starts melting.

:-)
  #3  
Old August 8th 06, 07:48 PM posted to sci.astro
Allan Adler
external usenet poster
 
Posts: 40
Default crust of neutron stars

Thanks for the pointer to the article on the iron weather on brown dwarfs.
I gather there is nothing we would consider ground for the iron to rain on.

If a substance is in crystalline form, we have a right to consider it solid,
and maybe we also consider something like glass a solid, an amorphous one.
On the other hand, to talk about stuff like continents and weather and
erosion, these notions might not be appropriate. Here are two illustrations
of what I mean by this:
(1) If someone jumps into the water from a very great height, they will
experience hitting the water in much the same way as if they hit concrete.
(2) The continents, which to our perception are so solid and immutable, move
very slowly over the lower SiMa layer (to use Wegener's terminology for
the substrate that the continents slide on). That SiMa layer is also
rock, but has a viscosity and flows under the weight of the continents.

So, for this context, it seems that we also have to take into account the
time scale when talking about how solid or liquid (or gaseous) things are.
In the case of Titan, the rate at which weather, as we know it, takes place
is very slow. In the case of the brown dwarf, it seems that the time scale is
very fast.

So, what I'm wondering is whether one can speak of relatively slower moving
components being eroded by relatively faster moving components, for example,
in the context of the crust of a neutron star or the surface of a brown dwarf.
--
Ignorantly,
Allan Adler
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.
 




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