Follow Slashdot blog updates by subscribing to our blog RSS feed

 


Forgot your password?
Close
typodupeerror
×
Space Science

The Secret of the Sun's Heated Atmosphere 158

Posted by kdawson from the ooh-shiny dept.
eldavojohn writes "There has long been speculation on why the Sun's surface is a mere ten thousand degrees while the atmosphere can reach millions. Space.com is reporting that the mystery has now been solved. Researchers looked for Alfven waves in the solar chromosphere and found them. Followup studies employing simulations demonstrated that the energetics work out to transfer energy from the Sun's surface to its overlying corona.. The magnetic waves may also be the power source behind the solar wind."
This discussion has been archived. No new comments can be posted.

The Secret of the Sun's Heated Atmosphere More

The Secret of the Sun's Heated Atmosphere

Comments Filter:

  • Did anybody else think... (Score:4, Funny)

    by tekiegreg ( 674773 ) * <tekieg1-slashdot@yahoo.com> on Tuesday January 22, 2008 @04:46PM (#22143302) Homepage Journal
    When I saw that article, I couldn't help but think "Damn that's a hot data center, glad I'm not running any of their servers :-) " then again if someone were truly able to get a computer running at that temperature, maybe they're worth considering...

  • Ah... (Score:4, Funny)

    by Anonymous Coward on Tuesday January 22, 2008 @04:53PM (#22143446)
    ...but does it run solaris?

    • pronunciation (Score:1, Informative)

      by Anonymous Coward
      Good joke, but...actually,

      - the correct spelling uses a diacritical mark over the 'e', as wikipedia indicates: "Alfén."
      - the correct pronunciation is more like ahlf'-vay-uhn or ahlf'-vay-n or ahlf'-vayn (with the last vowel sound a "schwa" nearly collapsed into the 'é' if it's even pronounced at all).

      I am not Swedish, but this is how I've heard native Swedish speakers pronounce it when asked specifically about how to pronounce his name.

      captcha: neutrino, no joke!

      • Re: (Score:2)

        by mangu ( 126918 )

        - the correct pronunciation is more like ahlf'-vay-uhn or ahlf'-vay-n or ahlf'-vayn (with the last vowel sound a "schwa" nearly collapsed into the 'é' if it's even pronounced at all).

        I am a native Swedish speaker (and Finnish as well)(BTW, and OT, so is Linus Torvalds...). The diacritical mark indicates the stressed sillable, so the pronunciation should be something like ahlf-VAY-n.
         
  • Hannes Alfven strongly advocated against magnetic reconnection and any theory of the corona's temperature that outright assumes that electricity is not involved. The idea that astrophysicists would attach his name to a theory that he vigorously fought against is a clear indication of peoples' lack of knowledge with regards to the history of science associated with his work. This has to be the ultimate form of scientific disrespect for what was in fact a very great man! Alfven started out as a power grid
    • I'm not sure where you get the idea that "electricity is not involved" in an Alfven wave. You can't have an Alfven wave without a plasma, and a plasma contains charged particles, which, when involved in a wave, move and generate electric current.

      FYI, the "corona" is a very hot plasma which surrounds the sun.... And which can support electric currents, and Alfven waves.

      As for your claim that people are saying that Maxwell's Equations are meaningless in space, I don't know how you infer that anyone is claim

      • Re: (Score:2)

        by pln2bz ( 449850 ) *
        You can parse my statement until it no longer makes sense in individual parts, but why try to so hard to assert that we know what is happening with the Sun when in fact all that is happening is that one line of reasoning has been developed to explain our observations of it?

        The point is that in the grand scheme of things, there are in fact alternative possible explanations for our observations which astrophysicists tend to ignore. They are complicit with ignoring these alternative explanations because math
        • Setting the record straight ...

          there are in fact alternative possible explanations for our observations which astrophysicists tend to ignore

          Or, more pertinently, these so-called alternatives fail several key tests, such as internal consistency, consistency with relevant theories whose domains of applicability overlap (quantum mechanics, in this case), and (above all) consistency with good, relevant observations.

          They are complicit with ignoring these alternative explanations because math already exists for the conventional paradigms

          And you know this because? Your objective evidence is ... what, exactly?

          The public has this misconception that astrophysicists have *ruled out* alternative explanations in an honest manner by completing a comprehensive review of all of the theories out there, and what one discovers over time is that in fact, that has not occurred in the slightest

          So, once again, if you please ... references to papers, published in relevant peer-reviewed journals, which lay out this/these 'al

        • Ignoring the filamentary nature of plasmas in space will always lead to garbage calculations. If it's not *our* theory, then it's not *our* responsibility to prove or disprove it!
          It appears that not only conventional scientists can play at that game...

    • Re:Alfven is turning in his grave! (Score:4, Insightful)

      by CheshireCatCO ( 185193 ) on Tuesday January 22, 2008 @05:52PM (#22144684) Homepage
      The waves are called "Alfven waves", with good reason. The fact that this then results in his name being attached to the theory is amusing, perhaps ironic, and arguably unfortunate, but hardly criminal. Shit happens when names are attached to things in math and science, it's something one has to just get used to.

      (The name name "big bang" was meant be disparaging, and yet here we are. Look up "Fuchsian groups" sometime, too.)

      And while you're at it, give astrophysicists a little credit. We do know physics, including E&M, pretty damn well. What's you're qualification to arm-chair quarterback on this?
    • I'm not familiar with Alfven, but I offer the following:

      Joseph Preistley [wikipedia.org] is credited with discovering oxygen.
      That's a wonderful honor and all except his opinion was that air gets clogged with "phlogiston" when material is burned, such that a fire within an enclosed environment gets extinguished because the air can no longer absorb this stuff.
      Nowadays, chemists understand that free oxygen gets depleted during a fire - which is the EXACT OPPOSITE of Preistley's strongly held belief.

      What can I say, "misplaced

    • Alfvén is smiling in his grave! (Score:4, Insightful)

      by APODNereid ( 1203758 ) on Tuesday January 22, 2008 @06:02PM (#22144874)

      Are astrophysicists just unaware, or are they being malicious?
      Neither.

      They have spent a decade or three researching magnetic reconnection - in the lab, via in situ space probes, and by remote sensing (a.k.a. using telescopes) - and have developed descriptions of the behaviours of plasmas, building on Alfvén's work and these discoveries, that match the observed phenomena nicely.

      Take a look at the Magnetic Reconnection Experiment (http://mrx.pppl.gov/ [pppl.gov]), as an example of lab-based plasma physics work on magnetic reconnection.

      But maybe you know something about the behaviour of plasmas that the thousands of researchers - experimentalists, theorists, 'observers', and those who simulate plasmas in computers - don't, or have missed?

      Why not write a paper to Nature, or Science, giving chapter and verse of the holes in their work?
    • Given that the Sun's outer layers are made up mostly of plasma (the high temperatures strip almost all of the electrons off the hydrogen and helium atoms), generating electric currents is not an issue.

      On the other hand, while electric fields are obviously present, they are weaker than the magnetic fields. The Sun has (essentially) no net charge. The electric fields are primarily created by the changing of the magnetic fields. This is generally a second order (ie. weaker) effect than the original magnetic fi

    • Re: (Score:3, Interesting)

      by adisakp ( 705706 )
      When you see a magnetic field, your first question should always be, "Where's the current?"

      Have you ever heard of permanent magnets?

      There are two methods of producing magnetism: 1) by current and 2) by aligning particles with non-zero magnetic moments (quantum spin) within a substance.

      Electromagnets use the first method while permanent magnets use the second.
  • The sun is a mass of incandescent gas - a gigantic nuclear furnace, where hydrogen is fused into helium at a temperature of millions of degrees. Scientists have found that the sun is a huge atom-smashing machine. The heat and light of the sun come from the nuclear reactions of hydrogen, carbon, nitrogen, and helium.
  • I'll bet Keebler's are pissed.
  • Maybe I should quit getting my info from television documentaries, but on the episode of the Universe (Astronomy program on the History Channel which debuted last year) dealing with the Sun, they stated that the likely cause of this was that the sound waves generated by the nuclear nature of the sun were causing enough pulsing/friction within the sun's atmosphere to superheat it compared to the surface.

    Is this still a viable theory? (or was it ever one?)

    • Re: (Score:2, Interesting)

      by pln2bz ( 449850 ) *
      The confusion with the Sun's inverse temperature situation (the corona is around 100x hotter than the Sun's surface) follows naturally from the theory that the Sun has a thermonuclear core, which originated around the time that we discovered that it *could* be the mechanism responsible for the tremendous energies we observe. But beware because the issue is by no means completely settled. Any theory that attempts to explain the inverse temperature problem must also grapple with the fact that the solar wind

      • the fact that the solar wind continues to accelerate even as it passes the planets!

        Er, no.

        This is just as inaccurate as your earlier comment about magnetic reconnection.

        If you - or any other reader - are interested, I could provide you with references to (recent) papers published in relevant peer-reviewed journals ... that describe what the dozen or so space missions have found, via in situ observations.

        The rest of your comment goes downhill from here ... (chapter and verse to follow, in case any SD reader hasn't yet cottoned on to just how cranky (shall we say) these ideas you keep push

        • Re: (Score:2)

          by pln2bz ( 449850 ) *
          Wow, Nereid. That appears to be your first outright lie. The solar wind does indeed continue to accelerate even as it passes the planets. Ionic velocities for both hydrogen and oxygen at the Earth are around 2 million mph, whereas oxygen travels at around 1 million mph and hydrogen at half of that at the upper corona.
          • You know, I could well be wrong about this.

            Would you be kind enough to give references to papers published in relevant peer-reviewed technical journals that support your original assertions?

            Please, only papers which report results from space probes that have sampled the inter-planetary medium, over significant time-frames.

            • Re: (Score:2)

              by pln2bz ( 449850 ) *
              It's actually non-controversial enough that we can just look it up in wikipedia. There are multiple references to the unsolved acceleration problem there ...

              http://en.wikipedia.org/wiki/Solar_wind [wikipedia.org]

              There is more discussion here, with an attempt to explain it ...

              http://www.obspm.fr/actual/nouvelle/jun05/solarw.en.shtml [obspm.fr]

              I pulled my data from "The Electric Sky", and they reference Peter Gallagher's conference on the subject, "Seminar on Observations and Modeling of the Corona and Solar Wind - Big Bear Solar Obse

              • Re: (Score:3, Interesting)

                by CheshireCatCO ( 185193 )
                Neither of your links says that the solar wind is accelerating as it passes Earth. Both say that it accelerates near the Sun (within a few solar radii), which *is* non-controversial and even predicted by Parker's original work. What Parker doesn't explain is the magnitude of the acceleration (see Kivelson and Russel's book, for example), but you're denying that, aren't you?

                Can you please bother to read your own links closely enough to verify their relevance? Simply posting a random link and saying, "here

        • Re: (Score:2)

          by ceoyoyo ( 59147 )
          Forget the peer reviewed papers. You can Google for graphs from SOHO and Voyager of solar wind speed. Guess which spacecraft measures it as going faster?

          (the answer is SOHO)

          Not that that will convince the nutjobs, of course.
      • Great. Another Electric Universe rant.

        • Re: (Score:1, Offtopic)

          by pln2bz ( 449850 ) *
          Personality and Social Psychology Bulletin, Vol. 26, No. 4, 474-485 (2000)
          DOI: 10.1177/0146167200266006
          © 2000 Society for Personality and Social Psychology, Inc.

          Jeer Pressure: The Behavioral Effects of Observing Ridicule of Others
          Leslie M. Janes
          University of Western Ontario

          James M. Olson

          University of Western Ontario, jolson@julian.uwo.ca

          Two experiments examined "jeer pressure," which is a hypothesized
          inhibiting effect of observing another person being ridiculed. Jeer
          pressure was expected to induce conf

          • What, exactly, is your point there? Are you suggesting that because you're being laughed it, you're right?
            • Cue the famous Carl Sagan quote: "But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown."

              He seems to be suggesting that ridiculing him in this case is evidence of a greater conspiracy to 'control' the spread of these ideas.

              I think the paper reference is at least interesting from another viewpoint - that astroturf marketers commonly

      • Re: (Score:1, Offtopic)

        by GaryPatterson ( 852699 )
        If the Electric Universe framework and Tesla's rumoured theories (little to nothing was published, leaving rumours and eyewitnesses as the main source of information) are correct, they'll stand up to testing and be accepted as valid.

        If they're not, they'll wither and die leaving only a handful of crank scientists supporting them.

        • Re: (Score:2)

          by pln2bz ( 449850 ) *

          If the Electric Universe framework and Tesla's rumoured theories (little to nothing was published, leaving rumours and eyewitnesses as the main source of information) are correct, they'll stand up to testing and be accepted as valid.

          If they're not, they'll wither and die leaving only a handful of crank scientists supporting them.

          You are quite correct, but I urge you to look closer at the linked-to material to get a better picture of the level of detail that in fact persists about Tesla. It is more than we

        • Re: (Score:2)

          by ceoyoyo ( 59147 )
          As far as I know the electric universe "theory" violates your prediction.

          It's only supported by a handful of crank non-scientists. Many of whom are Slashdot readers.
          • Actually, you're supporting my prediction.

            The Electric Universe has very little behind it in terms of hard science, and so falls by the wayside. It's in good company there, sitting next to phlogiston, the ether and other hypotheses. Maybe some good will come of it, but it's unlikely given that it's in opposition to theories we can actually test and disprove/prove.

            • Re: (Score:2)

              by ceoyoyo ( 59147 )
              No no, see, you predicted that only a few crank scientists would support it. I don't know of any crank scientists who support it, only the regular garden variety cranks.

              I'm not sure the electric universe has ANY hard science behind it. As far as I can tell it's an idea (the electric force plays a dominant role on solar system scales and up), that is constantly twisted around to explain any observation. Oh, there's a heft dose of "mainstream scientists are idiots" as well.

              An good example is our friend a f
              • My apologies, I phrased my original post poorly. I agree with everything you've said here, and I wondered about that magically accelerated solar wind as well.
      • What powers the Sun?

        Here is a good overview, written in 1996, of the standard solar model (SSM) (http://www.ap.stmarys.ca/~guenther/Level01/solar/what_is_ssm.html [stmarys.ca]).

        In a nutshell, the SSM matches a wide range of relevant observables, from the Sun's mass, its 'sound spectrum' (helioseismology - the solar equivalent of seismology), its radius, its energy output, the constancy of that energy output (time periods of years to billions of years), its (estimated, inferred) composition, and so on*.

        In 1996, there was

        • Re: (Score:2)

          by pln2bz ( 449850 ) *

          As far as I know, this 'Electric Universe' idea (EU) has no basis, either in terms of quantitatively matching any significant subset of the relevant observations, or in terms of the underlying theory (ask an EU proponent about how much experimental support there is for the EU idea of what supports the Sun against gravitational collapse, to take just one example; or to characterise the current which powers the Sun, in terms of charge carriers, flux, speeds, and so on, and how well this characterisation match

          • What people on Slashdot need to realize is that Nereid refuses to actually read what the Electric Universe says from one of the books that have been written on it

            I do? How do you know? Did I state that I refused to read some book? Did I state that I have not read some book?

            and yet viciously maintains that it cannot possibly be true. Caveat Emptor!

            I do? Can you back up that assertion with SD comments I've written?

            Or, perhaps, all I have said is that
            a) there are (AFAIK) no published papers, in relevant peer-reviewed journals, that support the {insert quoted EU assertion here}; and
            b) if there are, would you, pln2bz, please be kind enough to provide references to such papers (so I, and any other SD reader who may be interested, can read th

        • your mission (Score:1, Insightful)

          by Anonymous Coward

          If any reader is interested in reading more on this, right up to the latest ApJ papers, just holler!

          Since your relatively recent arrival amid these savage Slashdot forums, you seem to have made a point of rebutting junk science in general, and investigating pln2bz's (among others') junk science in particular. Those are admirable goals, and on behalf of myself and I suspect others who read Slashdot I say welcome and glad to have you.

          I know it takes time to do this, and it's a bother, but listing reliable links in comments (and quoting: even better) is an efficacious debate tactic and moreover a thorough d

          • Thanks for the kind words, AC! :-)

            Each internet discussion forum has its own rules, and within those rules, a wide range of writing styles and delivered content are possible.

            There's also the effectiveness of what's written, in terms of the writer's (or writers') intentions and goals.

            "Electric Universe" (and plasma universe, plasma cosmology, etc) ideas are all over the internet, with prolific proponents in a great many discussion fora. For some reason, such proponents seem to be particularly active in fora
            • Being a first draft on how to be more effective in addressing Electric Universe (Plasma Universe, etc) comments, posted in threads on stories in the Science section of SD.

              Empirically, such threads stay open for comments from 4 to at least 10 days; anyone have insights into how to accurately predict this lifespan?

              Empirically, you get ~3500 characters of text before "Read rest of this comment" kicks in (unless your score is high).

              SD itself gives guidelines on how a comment's score is arrived at (it's a dynami
            • Being a rather chaotic, eclectic collection of snippets ... not unlike how many scientific projects get started actually.

              leokor's SD comment is already noted; still the only EU SD comment that explicitly addresses the scope of this project that I have found.

              Quite a few AC's SD comments are quite insightful and helpful, so can be ruthlessly exploited*; for example:
              pln: "There is absolutely *nothing* about the Electric Universe that has been "debunked"."
              AC: "Everything not defined in terms so vague as to be u
              • Namely: what methods to use to develop the hypotheses and then test them?

                For example, if, upon detailed investigation, it turns out that the "rules of evidence" and/or "rules of logic/inference" and/or inherent immunity to falsifiability of the EU paradigm combine to be so weak as to preclude anything but the most facile of investigation, should I use such rules (etc) in my own investigations? If I do, and if they turn out to be so weak, I'll be stuck with the equivalent of "anything goes", won't I? If I

      • Re: (Score:3, Informative)

        by ceoyoyo ( 59147 )
        "the solar wind continues to accelerate even as it passes the planets!"

        No, it doesn't. I looked it up once before in an argument with an electric universe guy and I'm too lazy to do it again, but you can find the velocity of the solar wind as measured by SOHO and also by Voyager with a quick Google. I found an average value for Earth's neighborhood as well. Guess what? Fastest at SOHO, slower at Earth, slowest as measured by the Voyagers. That is, the solar wind slows down as it "passes the planets."
    • Don't know if this is still viable but I do remember seeing the same show. Perhaps it was just that, a theory... but they sure did a good job of presenting it as known fact. In any event, this article seems to refute the whole "sound theory for inverse temperature of the Sun".

      So no, you are not out of your mind... it was definitely presented as theory.
    • I didn't see the show, but there have been a number of theories as to the cause of the high temperature in the corona over the years. Alfven waves is a perennial favorite that has generally lacked data-support and/or a strong model to show how it happens. They're not actually sounds waves, but are a magneto-sonic -- generalized forms of sound waves in plasmas.

  • Must be because of the MySQL purchase?

    Oh wait...

  • Forgive my naivete but when I was a little boy I thought the sun was hotter due to convection. Hot things rise and are less dense. Cold things go down. Except this occurs with steroids on the sun.
    • First of all, convection only works in the outer 30% of the Sun (measured radially). Interior to that, photons carry the energy out.

      Second, convection only works if the exterior is cooler than the interior. Thermodynamically, heat doesn't move "uphill". So the fact that the corona is hotter than the photosphere (and hotter than most of the solar interior as well) isn't explained by convection at all.

    • Hot things rise and are less dense. Cold things go down. Except this occurs with steroids on the sun.

      But remember that there is no gravity at the centre of the sun, just as there is no gravity at the centre of the Earth. (OK, strictly speaking, there is micro-gravity.)

      Assume that the sun is pretty much a fluid (and ignore viscosity, or anything viscosity-like, such as electromagnetic attraction or repulsion in a plasma). This means that denser bits will sink to a point because the closer to the centre th

      • Yes, but if you get much outside the very center of the Sun, gravity kicks back in again. More massive stars than the Sun have convection zones that go deep into the interior. It's a question of where the thermal gradient exceeds the adiabatic lapse rate.
  • Sun : Very Hot, May cause personal injury.
    Sun : Warning, do not look directly in sun with remaining good eye.
  • Instead of "cool as a cucumber", we can now say "cool as the sun's surface". Of course, everybody who's not an astrophysicist (or a slashdot reader) will look at you like you've just grown a new head, but ... you can't have everything.

Slashdot Top Deals

Our OS who art in CPU, UNIX be thy name. Thy programs run, thy syscalls done, In kernel as it is in user!

Close