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Fraser
2005-Jul-28, 04:40 PM
SUMMARY: Take your estimate for the amount of neon in a star, and triple it. At least, that's what a team of astronomers using the Chandra X-Ray Observatory have concluded. They performed a detailed survey of 21 nearby sun-like stars within a distance of 400 light-years from Earth, and found they all contained an average of 3X the neon traditionally predicted for our Sun. Neon is difficult to find in stars because it doesn't give off any light in the visible spectrum. But when heated to millions of degrees, for example, in a star, this elusive element blazes in the X-ray spectrum.

View full article (http://www.universetoday.com/am/publish/chandra_discovery_solar_paradox.html)

What do you think about this story? Post your comments below.

antoniseb
2005-Jul-29, 02:51 PM
I've been watching the Bahcall group say that they thought increased Neon would explain things, and now here is evidence that there is more Neon than originally modelled. It is curious that the Sun is so bright that we can't look straight at it to try and see the xrays from Neon... There must be some way to set up the experiment.

om@umr.edu
2005-Jul-29, 10:55 PM
Originally posted by antoniseb@Jul 29 2005, 02:51 PM
I've been watching the Bahcall group say that they thought increased Neon would explain things, and now here is evidence that there is more Neon than originally modelled.
Really a remarkable coincidence, Anton.

With kind regards,

Oliver
http://www.umr.edu/~om

antoniseb
2005-Jul-29, 11:11 PM
Originally posted by om@umr.edu@Jul 29 2005, 10:55 PM
Really a remarkable coincidence
Funny, the way you expressed it sounds like you think that either the two facts are unrelated, or that the discovery of extra Neon is a matter of the will of the Bahcall team, and not a real observation. I'm sure you don't mean either.

Joff
2005-Jul-29, 11:46 PM
I wondered why we couldn't just look at a bit to one side of the sun, or scan it, or something...

So I looked on the Chandra site and one click further in, here (http://chandra.harvard.edu/photo/2005/neon/), I found:


...a gas heated to millions of degrees produces a distinct neon signal in X-rays. The upper atmospheres, or coronas, of stars like the Sun have temperatures of millions of degrees, so the solar corona would seem to be a good place to settle the argument (not with Chandra -- the bright solar radiation would irreparably damage the telescope). Unfortunately, the solar X-rays come from numerous localized loops of hot gas that vary from location to location and time to time, complicating the interpretation of the data on neon.

So we're just too fricking close to the sun - if we could look at the whole sun at once and collect the X-rays we'd be OK but not with any current instrument by the sound of it. Other stars we have no choice but to look at the whole thing at once. Just for once, this is an advantage.

Good work, Drake & Testa, and of course the Chandra team.

om@umr.edu
2005-Jul-30, 03:45 AM
Originally posted by antoniseb+Jul 29 2005, 11:11 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb &#064; Jul 29 2005, 11:11 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-om@umr.edu@Jul 29 2005, 10:55 PM
Really a remarkable coincidence
Funny, the way you expressed it sounds like you think that either the two facts are unrelated, or that the discovery of extra Neon is a matter of the will of the Bahcall team, and not a real observation. I&#39;m sure you don&#39;t mean either. [/b][/quote]
Hi, Anton.

It seems odd that the abundance of one element alone was changed.

Abundances of elements are tied together by the stellar nuclear reactions that made them.

For example, fusion of He-4 nuclei made the most abundant atoms of C, O, Ne, Mg, and Si:

3 He-4 -> C-12
4 He-4 -> O-16
5 He-4 -> Ne-20
6 He-4 -> Mg-24
7 He-4 -> Si-28

In the He-fusion series, an increase in the abundance of one corresponds to a decrease in the abundance of another.

That is why Fowler pointed out that that the value of O/C = 2 at the solar surface poses a serious difficulty in the most basic concepts of nuclear astrophysics. See "Two Serious Difficulties in the Most Basic Concepts of Nuclear Astrophysics" (http://web.umr.edu/~om/Fowler1988/CaldronsCosmos.pdf)

The anomalously low O/C ratio at the solar surface is explained in two new papers listed in my abbreviated resume.

It is encouraging that some solar physicists now recognize that they do not know what is inside the Sun. But the difficult road from the standard solar model cannot be by-passed by arbritary changes in the abundance of Neon.

With kind regards,

Oliver
http://www.umr.edu/~om

Nereid
2005-Jul-31, 01:11 PM
Abundances of elements are tied together by the stellar nuclear reactions that made them.

For example, fusion of He-4 nuclei made the most abundant atoms of C, O, Ne, Mg, and Si:

3 He-4 -> C-12
4 He-4 -> O-16
5 He-4 -> Ne-20
6 He-4 -> Mg-24
7 He-4 -> Si-28

In the He-fusion series, an increase in the abundance of one corresponds to a decrease in the abundance of another.
I&#39;m curious Oliver, wouldn&#39;t the ratio of &#39;metals&#39; (C, O, Ne, Mg, and Si, in this case; 10 ratios) in the core of a star be dependent upon the fine details of all the reactions taking place there (as well as their initial ratios)?

And the initial ratios would depend upon where the material which became the Sun came from (for example, do all stars which disgorge into the ISM the products of their core/shell nuclear reactions produce element ratios that are always the same?), would they not?

om@umr.edu
2005-Jul-31, 01:41 PM
Nereid,

My point is that elemental abundances are constrained by nuclear reaction cross-sections.

For elements made primarily by He-fusion, He -> C -> O -> Ne -> Mg -> Si etc., you can&#39;t go in and arbritarily increase the abundance of one (e.g., Ne) without also considering the affect on the abundances of others (e.g., Mg).

If the products "pile up" at Ne, then less Mg will be produced.

At the start of this series, it is difficult to get three He-4 atoms to fuse into C-12, but once that happens it is difficult to prevent the capture of another He-4 atom to make O-16.

That is why Willy Fowler pointed out that the value of O/C = 2 at the solar surface is one of the most serious difficulties in the most basic concepts of nuclear astrophysics. The ratio should be bigger.

Recently we showed that O/C = 10 inside the Sun ["The Oxygen to Carbon Ratio in the Solar Interior", Journal of Fusion Energy, vol. 23 (2005) pages 55-62].

With kind regards,

Oliver
http://www.umr.edu/~om

galacsi
2005-Jul-31, 05:13 PM
Originally posted by fraser@Jul 28 2005, 04:40 PM
SUMMARY: Take your estimate for the amount of neon in a star, and triple it. At least, that&#39;s what a team of astronomers using the Chandra X-Ray Observatory have concluded. They performed a detailed survey of 21 nearby sun-like stars within a distance of 400 light-years from Earth, and found they all contained an average of 3X the neon traditionally predicted for our Sun. Neon is difficult to find in stars because it doesn&#39;t give off any light in the visible spectrum. But when heated to millions of degrees, for example, in a star, this elusive element blazes in the X-ray spectrum.

View full article (http://www.universetoday.com/am/publish/chandra_discovery_solar_paradox.html)

What do you think about this story? Post your comments below.
Hello

A little rant :

So i learn the Neon paradox is solved. It is so exciting &#33;

I am more than a little surprised the solution came with remote stars and not by looking directly to the sun . And i dont undestand why . Somebody can tell ?

And iam rather surprised that such a problem still existed : Have we not been told , again and again , that the model is perfect and everything is under control ?

Nereid
2005-Jul-31, 05:28 PM
Originally posted by om@umr.edu@Jul 31 2005, 01:41 PM
Nereid,

My point is that elemental abundances are constrained by nuclear reaction cross-sections.

For elements made primarily by He-fusion, He -> C -> O -> Ne -> Mg -> Si etc., you can&#39;t go in and arbritarily increase the abundance of one (e.g., Ne) without also considering the affect on the abundances of others (e.g., Mg).

If the products "pile up" at Ne, then less Mg will be produced.

At the start of this series, it is difficult to get three He-4 atoms to fuse into C-12, but once that happens it is difficult to prevent the capture of another He-4 atom to make O-16.

That is why Willy Fowler pointed out that the value of O/C = 2 at the solar surface is one of the most serious difficulties in the most basic concepts of nuclear astrophysics. The ratio should be bigger.

Recently we showed that O/C = 10 inside the Sun ["The Oxygen to Carbon Ratio in the Solar Interior", Journal of Fusion Energy, vol. 23 (2005) pages 55-62].

With kind regards,

Oliver
http://www.umr.edu/~om
It seems we&#39;re &#39;talking past each other&#39; Oliver.

A ) On the one hand, we have various observations of the abundance ratios of various elements.

B ) On the other hand, we have the predictions of relative abundance of various elements, from stellar evolution models, which are built from nuclear reaction cross-sections, conservation laws, gravity, etc.

C ) On the third hand, we have the now highly detailed results from heilioseismology.

I understood this news story to be saying that B and C were consistent, and both also consistent with A except for the relative abundance of Ne. IOW, Ne was an anomaly.

Now the anomaly seems to have been resolved, by the finding that the Ne abundance is, in fact, close to that from B and C.

You seem to be saying that one cannot change the observed (relative) abundance of Ne without changing the observed abundance of Mg, Si, etc, because of some theory.

Specifically, you do NOT seem to be saying that B is inconsistent with C; your comment seems to be limited to reaction cross sections, which I&#39;m sure you&#39;d agree are but one set of input parameters to stellar evolution models.

(If I have misunderstood, I&#39;m sure you will set me straight).

Planetwatcher
2005-Aug-01, 02:00 AM
Hopefully this will dispell the Iron Sun notions.
More neon means less iron. Less iron means less discussion about iron suns. (I hope)

Guest
2005-Aug-01, 02:49 AM
Originally posted by galacsi@Jul 31 2005, 05:13 PM
Have we not been told, again and again, that the model is perfect and everything is under control ?
That&#39;s what I heard too, galacsi.

Patience. This too will pass.

With kind regards,

Oliver
http://www.umr.edu/~om

Planetwatcher
2005-Aug-01, 07:06 AM
A guy can always hope. ;) :rolleyes:

om@umr.edu
2005-Aug-01, 12:30 PM
Originally posted by Planetwatcher@Aug 1 2005, 02:00 AM
More neon means less iron.
No, making more Neon will not mean less Iron.

Helium burning does not make Iron.

Iron is made by the equilibrium process (e-process), near the supernova core, just outside the part of the star that collapses to form a neutron star.

With kind regards,

Oliver
http://www.umr.edu/~om

Nereid
2005-Aug-01, 01:13 PM
Iron is made by the equilibrium process (e-process), near the supernova core, just outside the part of the star that collapses to form a neutron star.
And the (relative) amount of H, He, [...], Ne, [...], Fe, [...] that at particular star has depends in a not-obviously-trivial-way on many, many factors besides one nuclear reaction process in one type of supernova.

Isn&#39;t it important that we work from the best observations we have? And aren&#39;t those the accurate helioseismological results?

Then we can take a look at theories of how elements are created (stellar evolution models), etc?

antoniseb
2005-Aug-01, 01:35 PM
Originally posted by Nereid@Aug 1 2005, 01:13 PM
Isn&#39;t it important that we work from the best observations we have? And aren&#39;t those the accurate helioseismological results?
Yes it is important to look at the best observations we have. I get the impression that there are several such observations of interest, and these include:

- helioseismological results
- spectroscopic studies of the photosphere and corona
- particle collection in situ (looking forward to Genesis results in a year or two).
- neutrino studies of the particular reactions in the Solar core
- studies of the magnetic field & sunspots
- overall luminosity measurements
- xray images of the surface and flares

All of these need to be studied to give a unified view. These should also be used when refining computer simulations. Certainly there has been a suggestion from these simulations that there SHOULD be more Neon than we&#39;d previously assumed there was. Now we have some evidence that there is more Neon than we thought. To me this suggests that there is a new clue about the sources of the materials that made up our pre-Solar nebula.

om@umr.edu
2005-Aug-01, 05:23 PM
Originally posted by antoniseb@Aug 1 2005, 01:35 PM
Yes it is important to look at the best observations we have, and these include:

- helioseismological results
- spectroscopic studies of the photosphere and corona
- particle collection in situ (looking forward to Genesis results in a year or two).
- neutrino studies of the particular reactions in the Solar core
- studies of the magnetic field & sunspots
- overall luminosity measurements
- x-ray images of the surface and flares

Hi, Anton.

Three other quantities have provided a great deal of information on the Sun:

1. Abundances of isotopes and elements in the solar wind

2. Abundances of isotopes and elements in solar flares.

3. Abundances of s-products in the photosphere compared to the number expected from neutron-capture cross-sections.

With kind regards,

Oliver
http://www.umr.edu/~0m

antoniseb
2005-Aug-01, 06:47 PM
Originally posted by om@umr.edu@Aug 1 2005, 05:23 PM
1. Abundances of isotopes and elements in the solar wind
2. Abundances of isotopes and elements in solar flares.
3. Abundances of s-products in the photosphere compared to the number expected from neutron-capture cross-sections.
These are inferred from my items two and three.

lswinford
2005-Aug-02, 03:25 PM
And how much of these elements do we allow to be bubbled up from the primordial cloud that condensed to make the sun--and how much is a product of fusion in the sun?

antoniseb
2005-Aug-02, 03:34 PM
Originally posted by lswinford@Aug 2 2005, 03:25 PM
And how much of these elements do we allow to be bubbled up from the primordial cloud that condensed to make the sun--and how much is a product of fusion in the sun?
The usual model says that none of the material seen in the surface of the Sun today are fusion products generated in the core of our Sun. Also, Helium would be the only fusion product building up in the Sun right now.

This Neon was created in a massive star that exploded before our Sun condensed out of the star forming region.

Guest
2005-Aug-02, 04:10 PM
Originally posted by lswinford@Aug 2 2005, 03:25 PM
And how much of these elements do we allow to be bubbled up from the primordial cloud that condensed to make the sun--and how much is a product of fusion in the sun?
Hi, Lswinford.

I agree with most of what Anton has written.

Elements like C, O, Ne, Mg, Si, S, Ar, etc. were made mostly by fusing together 3, 4, 5, 6, 7, 8, 9, etc. atoms of He-4 in a massive parent star.

Elements in the iron peak, like Fe and Ni, were made near the core by the equilibrium process when the parent star exploded as a supernova.

removed vague reference to an Alternative Theory

With kind regards,

Oliver
http://www.umr.edu/~om

antoniseb
2005-Aug-02, 04:29 PM
Originally posted by Guest@Aug 2 2005, 04:10 PM
Elements like C, O, Ne, Mg, Si, S, Ar, etc. were made mostly by fusing together 3, 4, 5, 6, 7, 8, 9, etc. atoms of He-4 in a massive parent star.
I have the impression that Carbon-12 is built up by getting three Helium-4 (alpha particles) nuclei together, and that Oxygen and Neon are made by adding Helium nuclei after the fact. I&#39;ve also been given to believe that most (not all) of the next ones that you mention are made from combining the various species of Carbon, Oxygen, and Neon in a later stage of stellar development.

Of course I&#39;ve never witnessed this up close, so I&#39;m only going on what old astronomy books told me.

lswinford
2005-Aug-02, 04:35 PM
Elements like C, O, Ne, Mg, Si, S, Ar, etc. were made mostly by fusing together 3, 4, 5, 6, 7, 8, 9, etc. atoms of He-4 in a massive parent star.

Elements in the iron peak, like Fe and Ni, were made near the core by the equilibrium process when the parent star exploded as a supernova.



That&#39;s a lot of mass&#33; (and yes, I know the pool that spews it can afford to do so)

I was also interested in the gloppiness of the process you mentioned earlier (in different terms), where one is favored at the expense of another. This makes me wonder if the convection zone discussed in the article has value not only in the energy it transmits, but mechanically mixes things. Without the physical mixing then some elements would be missed because the previous batch has impeded the progression. Mechanically, then, would an active convection zone then make for a more even mix of these helium fusion products? A stirred pot boils better.

Guest
2005-Aug-02, 05:16 PM
Originally posted by lswinford@Aug 2 2005, 04:35 PM
I was also interested in the gloppiness of the process you mentioned earlier (in different terms), where one is favored at the expense of another. This makes me wonder if the convection zone discussed in the article has value not only in the energy it transmits, but mechanically mixes things. Without the physical mixing then some elements would be missed because the previous batch has impeded the progression. Mechanically, then, would an active convection zone then make for a more even mix of these helium fusion products? A stirred pot boils better.
Hi, Lswinford.

Good questions&#33;

Isotope measurements show that material leaving the surface of the quiet Sun (i.e., in the quiet solar wind) is like

a.) alcohol-rich vapours leaving the quiet surface of a mixed drink*, or
b.) vapors leaving the surface of water in a gently heated tea kettle**.

However, material violently leaving the solar surface in a flare better represents the interior of the Sun, as does

a.) material that departs a mixed drink when someone bumps your elbow, or
b.) water leaving the tea kettle when it boils violently.

* The alcohol/water ratio is higher in the vapor than in the mixed drink.
** The H-1/H-2 ratio is higher in the vapor than in the tea kettle.

With kind regards,

Oliver
http://www.umr.edu/~om

lswinford
2005-Aug-03, 08:02 PM
Please forgive me in a possible "duh&#33;" moment, but while neon supposedly has no visible-light spectral signature (as I thought the article said), don&#39;t we use neon in lights around here? Does neon therefore contribute to the luminosity of these stars in consideration by virtue of ionic flows of plasma in the star&#39;s magnetic fields?

Now, I&#39;m not in that &#39;electric universe&#39; camp, so don&#39;t dismiss it on that account. But wouldn&#39;t a significant presence of neon at the surface or corona essentially turning the photosphere into as much a flourescent light as incandescent?

antoniseb
2005-Aug-03, 08:43 PM
Originally posted by lswinford@Aug 3 2005, 08:02 PM
Please forgive me in a possible "duh&#33;" moment, but while neon supposedly has no visible-light spectral signature (as I thought the article said), don&#39;t we use neon in lights around here?
Actually, I wondered the same thing.
http://www.ljcds.pvt.k12.ca.us/upperschool/projects/cyberchem/CYBERCHEM%20PROJECTS%201998-99/Weinberg%20Kevin/spectrallines.jpg

I&#39;d be curious to get a clarification on this point. I suspect that the journalist over-simplified something that the scientists told them.

Nereid
2005-Aug-03, 09:14 PM
Does neon therefore contribute to the luminosity of these stars in consideration by virtue of ionic flows of plasma in the star&#39;s magnetic fields?
Although I don&#39;t fully understand this question ("by virtue of ionic flows of plasma in the star&#39;s magnetic fields" - what on Sun does this mean???), to the extent that I do, the answer is NO&#33;

In some more detail: while &#39;metal&#39; lines do make an estimate of a star&#39;s total energy output, as determined from its &#39;optical&#39; spectrum, somewhat tricky (for some stars), Ne is such a minor contributor that it has no practical effect (of course, if you&#39;re down into the 1% or less in terms of &#39;model fit&#39;, then it may be important, along with a dozen other things).

Duane
2005-Aug-16, 08:07 PM
In a follow up story here (http://spaceflightnow.com/news/n0508/14neon/) I note that the Neon paradox really is important to understanding the differences between the theoritical model of our sun and what the helioseismology studies have revealed. The new value seems to have resolved that particular problem.

a quote from the article:


These Chandra results reassured astronomers the detailed physical theory behind the solar model is secure. Scientists use the model of the sun as a basis for understanding the structure and evolution of other stars, as well as many other areas of astrophysics.



The accepted amount of Neon used in our solar models appears to have been incorrect. I suspect that the difference will not be uttterly devastating to the model, (note the sarcasm&#33;&#33; It will change very little&#33;) but it will be interesting to see what comes of it, once the new values are punched in.




A little rant :

So i learn the Neon paradox is solved. It is so exciting &#33;

I am more than a little surprised the solution came with remote stars and not by looking directly to the sun . And i dont undestand why . Somebody can tell ?

And iam rather surprised that such a problem still existed : Have we not been told , again and again , that the model is perfect and everything is under control ?

No actually we have been told time and time again that the solar model we use is NOT perfect, and that it is subject to constant revision based on the observations that come from many different probes.

They could not look directly at the sun with Chandra, as it would destroy the primary instrument. There is also a problem with the closeness of the sun--the loops and CME&#39;s would make the identification of Neon very difficult.