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Space Science

The Solar Oxygen Crisis 158

Posted by CowboyNeal
from the clearing-the-air dept.
Astrophysicist writes "The Astrophysical Journal this week published an article about the abundance of oxygen in the Sun. Oxygen is the third most abundant atom in the universe, behind hydrogen and helium. Most of the hydrogen and helium was formed in the Big Bang, which means that oxygen is the element most frequently produced by nuclear fusion reactions in the interior of the stars. The solar abundance of oxygen, which is key in astrophysics because of its use as a calibration reference for other objects, was thought to be well established since the 80s. However, recent evidence indicates that it has been overestimated by almost a factor of two. A revision of the solar oxygen abundance would have a cascading effect on other important elements, such as carbon, nitrogen and neon, whose abundance is only known relative to that of oxygen. In addition to the impact on the chemical composition of many stars, models of solar interior may require some reworking in order to be consistent with the new data."
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The Solar Oxygen Crisis

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  • by iamacat (583406) on Saturday April 28, 2007 @11:14AM (#18912139)
    Before being swallowed by a red giant then? Or is amount of Helium proportionally larger?
  • Re:Crisis? (Score:3, Interesting)

    by zappepcs (820751) on Saturday April 28, 2007 @11:24AM (#18912213) Journal
    I think that if they have overestimated the amount of bright/visible matter in the universe, it might make a difference to how much dark matter they need to account for?
  • by kiyoshilionz (977589) on Saturday April 28, 2007 @11:34AM (#18912273)
    I assume you speak of Richard Feynman, the physicist that played bongo drums at a strip club? The physisict who would ask girls at a bar if they would sleep with him before he even bought them a drink? The one who won the 1965 Nobel Prize in Physics on quantum electrodynamics [wikipedia.org]? The professor at CalTech?

    All this is from his autobiography, a good read for all of geekdom, though to the OP's point it does make us feel way smarter than we really are.
  • Re:Crisis? (Score:3, Interesting)

    by IWannaBeAnAC (653701) on Saturday April 28, 2007 @12:16PM (#18912529)
    Maybe, but it wouldn't be that big a change, the estimated amount of dark matter is way more than the amount of visible matter anyway, needing a little bit more won't make much difference.
  • by Agent Orange (34692) <[christhom] [at] [gmail.com]> on Saturday April 28, 2007 @12:21PM (#18912559)
    This is not a new issue in astrophysics, and has been floating since 2004. There are two basic ways to measure the abundances. One is by looking at hte oscillations in the sun, and using those to probe the solar interior. This is called "helioseismology", since it is very similar to the way seismologists figure out the structure and composition of hte earth, by observing seismic waves.

    The other way is to take a spectrum of the sun (which is really just the solar photosphere -- the outer layers, or "atmosphere"). To interpret the spectra, one needs a model, which is used to derive the abundance (how much oxygen there is).

    Now...until recently the models used for deriving abundances were simple 1-dimensional models, which made some assumptions (such as "local thermodynamic equilibrium") and include some fudge factors to account for the fact that you're solving a 3-d problem in 1-d.

    The oxygen problem arises when you use accurate, 3-D models, which don't make the LTE assumption mentioned above -- called non-local thermodynamic equilibrium (NLTE). When one compares the abundances from the 3d NLTE models with what is expected from the helioseismology predictions, the discrepancy arises.

    Others have posted the link to the full journal article on the pre-print server (here [arxiv.org]). The introduction of this paper is a pretty good summary of the problem, albeit intended for a scientific audience.
  • by Thagg (9904) <thadbeier@gmail.com> on Saturday April 28, 2007 @12:38PM (#18912667) Journal
    There is a long tradition of this in physics. My favorite was "The Ultraviolet Catastrophe", which forecast that all energy would be increasing in frequency.

    The point of this kind of tounge-in-cheek hyperbole is to get people thinking about problems in a more creative, out-of-the-box way, and lead them toward solutions. The Ultraviolet Catastrophe led directly to Planck's quantum hypothesis -- which I don't think he even took as a serious solution at the time. But, it took that kind of wacky idea to get people over the hump of classical theory.

    I think that the Solar Oxygen Crisis people are trying to do something similar.

    Thad Beier
  • by Artifakt (700173) on Saturday April 28, 2007 @12:42PM (#18912703)
    It actually impacts a lot of theories, and definitely, just 'slashing some numbers' like a wal-mart price rollback is not all tht people should expect.

          Fred Hoyle's work would be the most obvious. Hoyle was the first physicist to model nucleosynthesis in stars (1948).* His theory there still seems sound (or the math behind it does, and the US, the British, and the former Soviet Union all spent more money testing some of that math than on all other scientific research ever funded by those governments, put together), and one implication is that Oxygen and all the other heavier elements, were produced almost exclusively in stars, not in the big bang. The current age of the sun, and it's projected lifespan, are both based partly on putting the mis-measured amount of Oxygen into Hoyle's equations.
            Hoyle is also known for having proposed a lot of rather odd theories later in his career, including some revised steady state theories, panspermia hypothisi, and so on. Some of those are based partly on his earlier math, and it's at least possible that this discovery will make some of the 'nutbar' Hoyle ideas less 'nutbar'. Hoyle's theories are even cited by some as real, solidly scientific proof of intelligent design. The impact there, whether it's real science or misinterpretation, would doubtless be phenominal, even (eu)catastropic.

    * There's actually a number of others involved, people such as Fowler, Chandrasekhar, the Alpher/Bethe/Gamow gang, and still others - I'm simplfying a bit in giving Sir Fred all the credit.

          Anyway, the sun may be less far along it's lifespan than we thought, possibly farther from the Helium Flash/red giant stage. (It still just about has to be about 5 billion years old, because independant geologic evidence suggests the earth is about 4.5 billion years old itself). So if the sun, and presumably related stars age more slowly than thought, then this possibly changes both supernova abundance and predicted spectrum and mass ratio numbers, and we have used those numbers to estimate the distance to distant galaxies, and the overall size and age of the universe.
            It's even quite possible that this change in Oxygen numbers means our estimates of the mass of the universe, it's age, and so on are all skewed, and super-novae may happen less frequently so that will also reduce our accuracy of measurement and mean it will take us longer to get enough new data to check the new predictions to the same accuracy as the ones we now doubt. Thus, this news not only predicts we may have to revise a lot of figures, but that it will be a bit harder to do it right than it appeared the first time.
            All the 'new physics bits', i.e. 'dark matter', 'dark energy', etc. all need refigured if the age and mass of the universe get refigured significantly. Some of them may be superfluous. Some new ideas may be needed. Yes, this could just possibly be that big (although it may well be much less significant in the end).
  • Re:Only a Abstract? (Score:3, Interesting)

    by Iron Condor (964856) on Saturday April 28, 2007 @03:47PM (#18913833)

    Actually, the abstract is all I need to see - they employ two techniques that yield results that differ from each other by 0.3dex yet they claim confidence limits on their measurements of 0.1dex.

    At that point we can file that under "some dudes PhD thesis" and forget about it.

    Incidentily, the best measurement of local cosmic abundances comes from cosmic rays, not from observations of the sun. They are so sensitive, that we can see the difference in abundance between elements with even or odd numbers of nuclei (which are minutely different in stability if you throw enough quantum mechanics at it).

  • by Iron Condor (964856) on Saturday April 28, 2007 @07:07PM (#18914797)

    Anyway, the sun may be less far along it's lifespan than we thought, possibly farther from the Helium Flash/red giant stage. (It still just about has to be about 5 billion years old, because independant geologic evidence suggests the earth is about 4.5 billion years old itself). So if the sun, and presumably related stars age more slowly than thought,[...]

    Why do laymen who have never even taken an introductory astro-101 class imagine they're qualified to second-guess the result of other poeple's life's work?

    What you write up there is utter rubbish. Pop-II models do not age significantly different from Pop-I models even though they contain many orders of magnitude less oxygen. Because (surprise, surprise) the main-sequence life span of a star is governed by Hydrogen. Heavier elements do not figure in at all untill the very last phases after hydrogen has been exhausted except in the case of stars many times more massive than the sun.

    As it turns out the sun is not many times more massive than the sun.

    If the abundance of C, N or O had any particularly interesting effect on the main-sequence time of stellar models, then we could compare the models with the observations and derive the abundances from that. Because there's a metric shitload of main sequence stars out there. And one is right here close by, ready to be studied.

    Where do people get the idea that a revision of the solar composition at the level of a percent-of-a-percent would have any particularly interesting effects on our stellar models? Especially if these values have always been known to be uncertain?

    And this new value certainly isn't going to convince anybody to change the books. It's just yet-one-more in a pool of dozens, nay, probably hundreds of measurements; all of which when taken together and tested against each other and corroborated against the observational data produce something like a scientific consensus if and only if they manage to stand these tests.

  • by physicsnick (1031656) on Sunday April 29, 2007 @10:13AM (#18918793)
    Actually, Earth might not be swallowed up when the sun turns into a red giant. The sun will expand to over 1 AU, but that will take several billion years; meanwhile Earth's orbit is slowly drifting outward. By the time the sun expands, Earth might be out at the distance of Jupiter or so.

    Don't quote me on this. I don't have any real source; I just read it on How to destroy the Earth [qntm.org].

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