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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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  • Full Article (Score:5, Informative)

    by Betelgeuse (35904) on Saturday April 28, 2007 @12:17PM (#18912161) Homepage
    You can find the full article of this at the Astrophysics Preprint server. See here. [arxiv.org]
  • by meringuoid (568297) on Saturday April 28, 2007 @01:02PM (#18912451)
    Maybe, someone can clue in eveyone else on exactly how fundamental less oxygen is to particular theories? Do any of them just seem like crap now, or can all the numbers just be slashed to make the same point?

    Oxygen is a by-product of nuclear fusion in some stars. Hydrogen is burnt to helium in the main-sequence part of a star's life, helium is burnt to carbon in the red giant phase, and after that there are a sequence of short-lived reactions that only take place in the larger stars, in which carbon is burnt oxygen and oxygen is burnt to a whole bunch of things [astrophysi...ctator.com].

    The nuclear physics of all this is well understood, so if the amount of oxygen in the Sun is less than we'd anticipated then that means we've got something wrong about how we understand the insides of stars, about the pressures and temperatures that hold there. It might mean that fewer stars ever get around to producing oxygen, or perhaps that more stars make it all the way to burning it up again, or it might tell us there was something unusual about the nebula our own sun came from. It means, basically, that there's some interesting astrophysics waiting to be done, and that's enough to make astrophysicists very happy :-)

  • by Soul-Burn666 (574119) on Saturday April 28, 2007 @01:09PM (#18912491) Journal
    You mean something along the lines of a Dyson Sphere [wikipedia.org]?
  • by Anonymous Coward on Saturday April 28, 2007 @01:10PM (#18912497)
    The general consensus for decades has been that the solar interior and its basic nuclear chemistry was pretty well understood. This finding, if it holds up, will affect virtually all solar physics relative to our own solar system and much, perhaps most, of the physics we imagine going on in remote stars. For instance, the solar neutrino problem (not seeing enough of the right kinds of neutrinoes here on earth) may be strongly affected by this - we thought there was a "neutrino problem" precisely because we were extremely confident we knew the processes in the sun to high precision. This means everything has to be looked at, again, in regard to solar neutrinoes, and most other aspects of solar physics. As large a disagreement from previous results as this means we really don't understand the sun as well as we previously thought - your model is not just a few per cent off, but is off by multiples......
  • Re:Crisis? (Score:3, Informative)

    by Agent Orange (34692) <christhom@gm[ ].com ['ail' in gap]> on Saturday April 28, 2007 @01:34PM (#18912633)
    complete bullshit. This has nothing to do with dark matter, or the amount of visible mass. It merely tells you what percentage of the sun is comprised of oxygen. It is a very tiny amount. For every oxygen atom, there are about a 1000 hydrogen atoms and a hundred helium atoms.

    The evidence for dark matter is based on other observations, like the way disk galaxy's rotate. In order to reproduce those observations, dark matter is required.

    The estimate of the total amount of mass in various phases (e.g. stars, cold gas, hot gas, etc etc) in the universe has been done. You can read the paper here [arxiv.org]. Look at table 1. This is the contribution of all the different things to the total energy-density of the universe. What is amazing is the *tiny* fraction of the total energy-density that is made from baryons (visible, observable stuff). It's only about 4% or so. 23% is dark matter, and the rest is "dark energy".
  • by Anonymous Coward on Saturday April 28, 2007 @02:16PM (#18912941)
    You are only talking about the relative mass index of the atoms, which is not necessarily the same as their relative abundances. IAAPStudent and my formation about this is limited, but here's what I know:
    H is the most abundant, being by definition a single proton.
    He is the second most abundant, most of it having been formed during the big bang (2 protons, 2 neutrons).
    The next one in the chain, however, is not Li or even Be as one might think - the most massive stars use He to create carbon - through a few different pathways using a few intermediary, unstable nucleis - while Li, Be and Bo are generally byproducts of the disintegration of some of those unstable nucleis, making them actually rarer than C itself.
    What I don't know is why O is third while C isn't - I'd guess this is because most of the C is then used to create oxygen in another fusion chain involving C and He, whose rate is relatively quick considering only 2 nuclei are involved. However, C itself is a product of a long chain involving 3 He and many intermediary steps, which makes sure that the reaction rate is slow. Thus, a few stars (that aren't massive enough to continue the chain) will stop at carbon production, but all of the more massive stars will gobble up the carbon as soon as it is created to use it to fusion He and C into O.
  • Re:Hard luck (Score:2, Informative)

    by Anonymous Coward on Saturday April 28, 2007 @03:58PM (#18913545)
    Interesting shock site in that link (you don't really want to click).

    The damn thing crashed my firefox with noscript on linux!

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