The newest version of the most commonly used Standard Solar Model (SSM) in PDF format. It may be useful for those discussing solar or stellar evolution, makeup, etc.

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Humanity must rise above the Earth, to the top of the atmosphere and beyond, for only then will we fully understand the world in which we live.~Socrates, 500 B.C. ~

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Thanks Duane, this is a good find. This quote caught my eye:
The "Standard Solar Model" is constantly evolving through hard work and observation, but it says nothing about how the sun formed. There must be different technical terms than name the current model of how the sun formed. Any idea what this name is?

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Forming opinions as we speak

Hmm, well you might try "pre-main sequence solar evolution" or even "Early solar evolution". Might also try researchers names, especially those associated with the early work to determine solar evolution--Bahcall obviously, but also Iben, Grevesse and Sauval, Brown and Sawyer, and Schwartz.

__________________
All civilizations become either spacefaring or extinct.~ Carl Sagan ~

Humanity must rise above the Earth, to the top of the atmosphere and beyond, for only then will we fully understand the world in which we live.~Socrates, 500 B.C. ~

Let every man judge according to his own standards, by what he has himself read, not by what others tell him. ~Albert Einstein~

Oliver incoming! h34r:

In 5...4...3...2...

I suggest that linking to an abstract page, or an index page of some kind is maybe better than linking straight to the PDF. That way people can open the webpage, see the abstract, and decide if they want the PDF (especially the folks with slow or troublesome connections). Solar Models: current epoch and time dependences, neutrinos, and helioseismological properties, J. Bahcall, M.N. Pinsonneault & Sarbani Basu, Astrophysical Journal 555: 990-1012, July 10, 2001.

But there are more recent papers along the same lines, of some interest. Helioseismological Implications of Recent Solar Abundance Determinations, Bahcall, Pinsonneault, Basu & Serenelli, Astrophysical Journal (in press). This one addresses the recent determination that the lighter heavy elements are less abundant in the solar photosphere than previously thought (The solar chemical composition, Asplund, Grevesse & Sauval, in press). Bahcall, et al., have determined that these results imply in turn that the opacities may have been underestimated by about 10%. But an updated computation of the OPAL opacities show an increase no more than 2.5% (Up-dated opacities from the Opacity Project, N.R. Badnell, et al., submitted to Monthly Notices of the Royal Astronomical Society; A comparison of Rosseland-mean opacities from OP and OPAL, Seaton & Badnell, Monthly Notices of the Royal Astronomical Society 354 (2): 457-465, October 21, 2004). So some kind of problem still remains here. However, note that it is on the order of a few percent, whereas the assumption that the sun is dominated by heavier elements brings about a discrepancy so great, it was recognized as significant 80 years ago.

The PDF that Duane linked to is hosted from John Bahcall's webpage, which is a good place to look for solar stuff. Just follow the links to popular or technical articles. Most of his work has focused on solar neutrinos, and he got into the solar modeling business by necessity, as the expected neutrino fluxes also depend somewhat on the adopted solar model. And while I'm at it, why not put in a plug for my own webpage: Solar Fusion & Neutrinos? it's not exactly solar modeling, but it's a pretty good review of the standard model of nuclear fusion in the sun, if I do say so myself.

As for solar evolution, indeed that is different from the snapshot in time that is the current standard solar model. Just think of it as "standard solar evolution". But the evolutionary model must reproduce the current observed sun. There is a lot of scientific literature out there on the subject. For instance, Updated Toulouse solar models including the diffusion-circulation coupling and the effect of µ-gradients, O. Richard, S. Théado & S. Vauclair, Solar Physics 220(2): 243-259, April 2004. The authors here show how the inclusion of rotation & convection induced mixing, added to the evolutionary model, can reproduce interesting details of the current sun, such as the fact that lithium is depleted over time, while beryllium is not.

I think the 1998 solar evolution model by Turcotte, et al. is the one most commonly referenced: Consistent Solar Evolution Model Including Diffusion and Radiative Acceleration Effects, S. Turcotte, et al., Astrophysical Journal 504(1): 539-558, September 28, 1998 (the ADS shows 42 citations, but the Caltech index shows 45). Of course, the details of solar evolution depend on tjhe same opacities that are at the root of the abundance - helioseismology controversy, and are equally subject to modification. Many of Sylvain Turcotte's papers, this one included, are also downloadable on the web.

One interesting future for solar modeling: the Djehuty project at Lawrence Livermore National Laboratory. This is, so far as I know, the only operating, fully 3-dimensional, hydrodynamic solar/stellar modeling code. All of the PR (and this webpage) date from 2002, and I don't know what the current status is (it's a bear of a problem). But that kind of computational power, turned loose on the kind of detailed models developed by Bahcall and others, could solve the problems of modeling the current sun and it's evolution over time.

The Standard Solar Model is the current stage of about 100 years of serious, "modern" scientific research. It may not be perfect, but it is certainly head & shoulders above the competition.

Cheers.

Thanks for the links and valuable resources, the SSM model still, as Tim thompson alluded to, shimnes above and beyond any and all alternative models

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Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art

Duane Sir,
how many ssm models are there? and which is pure? i mean which is real?

The "Standard Solar Model" and the nebular model of forming the solar system are continually being changed to try to accomodate new experimantal findings.

It was changed to try to explain short-lived elements at the birth of the solar system.

It was changed to try to explain un-mixed products of nucleosynthesis in meteorites and planets.

Neutrino oscillations were proposed to try to fix one major problem.

The low O/C ratio in the photosphere is another unexplained observation.

Currently the SSM is being changed again to try to fit a 40% decline in the Sun's metalicity.

The SSM has been revised so many times that only the name remains.

Here are some of the observations unexplained by the SSM

http://web.umr.edu/~om/aasaapt.prn.pdf

With kind regards,

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

Proposed, and confirmed, adding to the strength of the argument for the current model.

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Forming opinions as we speak

This is an alternative solar system theory "fission".

http://www.metaresearch.org/solar%20system...olar-system.asp

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Indeed so. However, one might ask the obvious question: Is this a good thing or a bad thing? The equally obvious answer is that this is a good thing. After all, theories are supposed to represent reality in some way, and observation is the practical definition of reality, so altering a theory to fit the observations is clearly what you want to see scientists doing. The common practice in science is to continually adjust any theory, to take into account new and more accurate/precise observations. Only when the adjustments become unreasonable in the context of the model, do we simply scrap the theory altogether and start over again with a new theory.

Looks impressive, but looks can be deceiving. Consider a paragraph from one of my earlier messages in the iron sun discussion:

Now, (0.0275-0.0165)/(0.0275) = 0.40, which is where the "40% decline in the Sun's metalicity" comes from. Metalicity is defined as a ratio Z/X, but if you just look at Z, the fractional metal content of the sun as a whole, the number becomes less than 1%, a rather less impressive looking number.

I am more impressd by the fact that the standard solar model is so sensitive to the sun's metalicity, that if the metal content of the sun is changed by less than 1%, then the consequent implied change in the physical structure of the sun is well outside the parameters allowed by the model. This is exactly what you want from a scientific model, a sensitivity that can be tested at small scales. Prof. Manuel would have us believe that this is a sign of weakness, that somehow the standard model is weak because it has to be adjusted. In fact, the opposite is the case. it is a sign of strength in the standard model that it is homing in on a representation of the sun that varies at the 1% level, not at the 40% level.

Actually, it's not quite that simple. The original neutrino problem was that the count of neutrinos detected from the sun amounted to only about 1/3 of the expected number. Two possible solutions immediately come to mind: (1) the physical model of the sun is in error, and (2) the physical model of a neutrino is in error. In fact, both of these pathways were vigorously pursued, by both solar & particle physicists, each trying to solve the problem in light of their own specialties. Solar physicists were able to show, primarily by helioseismology, that the physical model of the sun was not so uncertain that it could be adjusted to accomodate the observed neutrino counts. But particle physicsts showed that neutrino oscillations (a change from one type of neutrino to another) was a realistic possibility. This latter possiblity of oscillations was supported by counts of solar neutrinos of all 3 types (the original counting experiments were sensitive to one type only), and by neutrino counts at nuclear reactors.

So, neutrino oscillations were not just "proposed", they were proposed after lengthy study, and then they were confirmed. There is no longer any question about this confirmed solution in the community of solar & particle physicists.

Prof. Manuel portrays the standard model as untrustworthy, but his portrayal does not match well with reality. Of course, the standard solar model is not "perfect", and like any scientific model, faces its own share of questions & problems still. But are those problems so large, or the answers to questions so uncertain, that the "slop" in the standard model is large enough to accomodate a "mostly iron" sun? Or perhaps an "electric" sun? I see no indication that it is. And I see no indication that the standard model violates any fundamental sensitivity of the physicst. The standard model is "standard" for a reason, and that reason is not political, or social, or even economic. It is scientiific. The standard model is "standard" because it's the best one available, and the competition, so far, just can't stand the heat of the solar kitchen!

I am adding this message, with links to some papers of interest from the New Journal of Physics. This is an "open access'" journal, or so they say, so anyone should be able to read the papers in html or PDF, without a subscription. The papers I will link to here are with reference to the standard solar models & the "solar neutrino problem".

Evidence for the MSW effect, Gianluigi Fogli and Eligio Lisi, October 25, 2004. The MSW effect is the neutrino oscillation mechanism. This paper reviews the observational evidence that this effect actually happens, and neutrinos do "oscillate".

Reactor neutrino oscillation studies with KamLAND, K. Inoue, October 28, 2004. This paper specifically reviews the observation of neutrino oscillations at the KamLAND reactor. This shows, along with the previous paper, that neutrino oscillations are not just somebody's theoretical "guess", and they are not just "observed" with solar neutrinos. Neutrino oscillations are observed in a laboratory setting, independent of solar neutrinos entirely.

Solar neutrinos, A.B. McDonald, September 23, 2004. A review of the current solar neutrino experiments.

My purpose here is to introduce some of the scientific literature which shows rather conclusively, that the "solar neutrino problem" is a solved problem, and that the real observation of neutrino oscillations is that solution. Also see Solar neutrinos: history from John Bahcall.

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