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Astronomers Find Unusual Star 203

First time accepted submitter JoshuaZ writes "Astronomers have found an unusual small star. SDSS J102915+172927 is a small faint star with very little of any elements other than hydrogen or helium. The star's composition is surprising (Pdf) since standard theories of star formation require heavier elements in small stars in order to allow the stars to be heavy enough to come together. Possibly the most unusual aspect of this star is the complete non-detection of lithium which would be expected in a star of this size. The only elements created shortly after the Big Bang were lithium, hydrogen and helium, and the star should have lithium levels much higher since they should correspond closely with the levels believed to have been formed shortly after the Big Bang."
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Astronomers Find Unusual Star

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  • Well then (Score:4, Funny)

    by coreboarder ( 412771 ) on Friday September 02, 2011 @01:09AM (#37282938)

    That is unusual.

    • Re:Well then (Score:4, Insightful)

      by repapetilto ( 1219852 ) on Friday September 02, 2011 @01:18AM (#37282974)

      So the next question is: How would someone go about mining a star?

      • Magic.
      • "So the next question is: How would someone go about mining a star?"

        Are you suggesting that we go mine it for Helium, or suggesting that some other race has already been there and pretty much cleaned the place out?

        • Re:Well then (Score:4, Interesting)

          by repapetilto ( 1219852 ) on Friday September 02, 2011 @01:47AM (#37283084)

          Someone mined the heavier elements.

          • It's considerably more likely that our theory(/ies) of star formation are lacking.

            • by tgd ( 2822 )

              I've always found Occam's Razor an interesting thing to invoke in cases like this. While I agree with the contention that the simplest explanation is likely the right one, that statement means nothing at all if you don't have a pretty good sense of the situation.

              The assumption that its considerably more likely our theories of star formation are wrong is based on a couple presumptions that may be correct, but may not:

              - life is uncommon
              - intelligent life is even more uncommon
              - intelligent life goes extinct be

              • Re:Occam's Razor (Score:5, Informative)

                by TheRaven64 ( 641858 ) on Friday September 02, 2011 @08:03AM (#37284506) Journal

                While I agree with the contention that the simplest explanation is likely the right one

                Why would you agree with something so nonsensical? And why would you state such a belief in the context of Occam's Razor, which says nothing of the kind. Occam's Razor says that, if a model works without one of its factors, then it is safe to remove that factor. It's a rule about logic, not about science. If you start with a set of axioms and develop a system, then there are an infinite number of axioms that you can add without changing the validity of any of your interred rules, but adding these does not gain you anything.

                An example of its application in science is the idea of guided evolution. One model suggests that species change via random mutations. Another model suggests that these changes are not random, that they're guided by a higher power in such a way that is indistinguishable from random change. Occam does not say that the second hypothesis is wrong, merely that it adds nothing useful to the model. You could also add another factor to that saying that it's guided by a higher power who makes decisions based on what an angel tells him. You could go on adding extra layers to this hypothesis forever, without altering the predictions that are made. You can, therefore, save yourself some mental effort by ignoring the factors that are irrelevant.

                That doesn't mean that the first theory is 'right', or true, it just means that it's simpler and equally useful.

              • None of those assumptions remotely approximate the least degree of scientific consensus - the debate is still strongly happening on them.

                The evidence we do have can support two conclusions:
                1) Life is very fragile and that it happened on earth at all is rare, unique and may never have managed to happen anywhere else.
                2) Life is very resilient and has survived despite everything the universe has thrown at is (mostly giant, icy rocks) and continues to survive everywhere it can and everywhere it can't.

                The extinc

                • by danlip ( 737336 )

                  "fragile" really isn't the right word for your first statement. The question is what are the chances of a bunch of molecules coming together in just the right way for life to happen (ignoring panspermia or divine intervention, both of which I consider equally (un)plausible). This is hard to answer, so life could be everywhere or nowhere but earth. Once it occurs it rapidly diversifies which makes it very robust.

                  • Except we have at least 8 viable theories on abiogenesis - none of which are proven - all of which are possible.
                    Who says there is only ONE right way for life to start ?

              • by fyngyrz ( 762201 )

                No, it's based on how difficult it would be to mine elements from a star. We *know* that is difficult to the point of near-impossibility; we *guess* that the universe started with a big bang (and we are trying hard to make a theory with a lot of holes fit better, since it fits the best of the various pretty bad theories we have.)

                The OP said the star was mined. I responded by questioning our star formation theories instead because it's a much simpler and more likely place to find an answer. As opposed to ali

                • True, but, since I don't know much about the technicalities of star formation, the mining thing seemed like a more interesting question to ask.

            • >It's considerably more likely that our theory(/ies) of star formation are lacking.

              It's even MORE likely that our theories are generally correct but some specific unknown circumstance caused this particular star to follow a different and unexpected path. This star is not matching the previously observed observations on which our theories are based. The most likely explanation is that something highly unusual (perhaps entirely unique) happened here - we don't yet know what, something that cause it not to

      • A proximity trigger would be the most useful.

      • by mbone ( 558574 )

        Mine the Giant Molecular Clouds where stars are made. If you wanted to make lots of Dyson sphere habitats, O'Neil Cylinders, or Jupiter Brains, that is where you would do it. The resulting stars would lack whatever elements you really needed.

        The real question is, why would they want all of the lithium ? Maybe for fusion power (as Castle Bravo showed, lithium-7 captures a neutron and splits into an alpha particle, a tritium nucleus, and the captured neutron, and tritium / Helium fuse well). Either such minin

      • Well, since Stargate Universe was a documentary, must have been some ancient civilization that used the star to power their intergalactic ships. Duh.

        Or, conversely, as someone has already mentioned Occams Razor, maybe they got the size or other readings wrong, and it's not small or the elements aren't missing?
    • Re:Well then (Score:4, Interesting)

      by SharpFang ( 651121 ) on Friday September 02, 2011 @01:28AM (#37283006) Homepage Journal

      That's no star. It's artificial sun.

    • That's no star -- it's an extragalactic surfboard flare [youtube.com]!

      (Ok, that wasn't very witty. Superior replies encouraged.)

      On a more serious note: given that the Milky Way's diameter is ~100,000 light years, this thing being only "3,500 light-years above the disc of the Milky Way" would make it a straggling member of our galaxy, would it not?

      • The milky way is a disc (as your quote says). It's only 1,000 light years thick, so 3,500 light years is quite a long way away from the galaxy.
        • by GPS Pilot ( 3683 )

          It would be interesting to know how many "standard deviations" it is from the plane of the galaxy.

    • Unusual star?

      It is David Bowie?

      How about Crispin Glover?

  • by rubycodez ( 864176 ) on Friday September 02, 2011 @01:27AM (#37283004)
    I always like to know how far away something is from us. Most articles on the web give direction toward Leo, but for distance I only found one reference that said it was hovering 3,500 light-years above the disk of the Milky Way. So it's near our Milky Way

    http://www.cosmosmagazine.com/news/4690/impossible-star-discovered [cosmosmagazine.com]
    • by SplashMyBandit ( 1543257 ) on Friday September 02, 2011 @01:47AM (#37283086)
      That's because it is so damn hard to measure distance, so sometimes even an approximate distance is not given (but as you imply, distances should be given when known or a reasonable guess is available). That's because the most straightforward way requires you to know the 'extinction' of light towards your particular star. That means, you need to have a measurement of blocking effect of (non-emitting) gas nearby and hope it applies to your (hopefully nearby) object of interest. If you are lucky you'll get a reasonable estimate for distance that is probably within an order of magnitude of the true value, and sometimes you might even get down to a factor of two in uncertainty. And this is just for stuff relatively close in our galaxy. Getting distances elsewhere can be even harder. Disclaimer: IAAFA (I am a former astrophysicist).
      • by Michael Woodhams ( 112247 ) on Friday September 02, 2011 @02:33AM (#37283274) Journal

        For a main sequence star, the procedure would normally go something like this:
        From the star's spectrum, you know its temperature. (With a good enough spectrum, you can also confirm that it is main sequence.) From the temperature and the fact it is main sequence you know its intrinsic luminosity pretty well. From its temperature you know its intrinsic colour well. Comparing this to the observed colour, you infer how much dust there is between you and the star. (Dust blocks blue light more strongly than red light, so more dust means redder colour.) Knowing how much dust there is, you know how much its observed brightness has been reduced by the dust. Knowing what its brightness would be without dust and its intrinsic luminosity, you use the inverse square law to figure out how far away it is.

        However, this star would have a really weird spectrum. If I recall correctly, hydrogen and helium only show spectral lines in much hotter stars, so presumably the only lines are calcium (the only metal they did detect). I don't know how well they can determine temperature with just calcium lines. I'm also not sure how precise this procedure is on ordinary stars, but I'd guess the uncertainty in distance would be about 10-30%.

        IAAFA also, but I've never actually used the procedure I describe above.

        • IAAFA? I am a fucking astronomer? ;)

          No, seriously, thanks for the explanation. Regarding the H and He lines - as a (bio)chemist, who admittedly hasn't done much optical spectroscopy lately, I still think that you should at least see the absorption lines regardless of temperature. Not sure how that would figure into temperature determination, but hey, I used to work with single molecules. Stars are way to big for me ;)

          • by Teancum ( 67324 )

            The issue that comes from stellar spectra is that you have different layers emitting/absorbing light, so you get different characteristics depending on the temperature of the star and the temperature of its surface. So you get both absorption and emission lines, sometimes of the same element and certainly a healthy mixture of a great many elements simultaneously.

            A whole lot of information is packed into stellar spectra together with the ability to "repeat" the measurement literally billions of times for ot

        • Of course, that's if the star is bright enough to do spectroscopy. Most of them are good only for photometry, no?
        • That's for close stars though right? How would you distinguish reddening from dust and reddening from red-shift caused by expansion at greater distances?
          • by mangu ( 126918 )

            Red shift only appears for other galaxies. In our galaxy relative movements of stars are much bigger than the effect of the expansion of the universe.

          • by mangu ( 126918 )

            Sorry for replying again, but Slashdot doesn't allow one to edit comments.

            Another relevant factor is that in red shift the spectral lines are shifted towards the red end of the spectrum. The reddening from dust does not shift the lines, just makes the blue part of the spectrum fainter.

          • by nusuth ( 520833 )

            I am not an astrophysicist but red-shift shifts all absorption lines in the same proportion while preferentially absorbing blue light would not have such an effect.

        • Thank you for the very informative post.

          This procedure seems very well thought out, and I assume that its validity has been tested by other methods, such as parallax. Do we have similar methods for non-MS stars?

        • yes, great stuff. but in this particular case they seem to know a rough approximation of distance but instead only gave us equivalent of projection onto one coordinate axis. So let's see, galactic center is about 19 hour RA and -25 degrees down. Leo (and so roughly this star), is 11 hours RA and +15 degrees up. the main thing being that this is roughly 40 degrees up from galactic center which we'll call the plane of the galaxy. So we make a leg 3,500 light-years up to the star from the plane if that
  • In a sense this is a good thing. It shows that when you really get down to it, we still really understand very little about the universe and how things are formed/created. A little humility never hurt.
  • ...we could easily confuse an exhaust with a star...

  • by BenSchuarmer ( 922752 ) on Friday September 02, 2011 @01:41AM (#37283056)
    Jupiter [wikipedia.org] is also like 99.7% hydrogen and helium, but I guess they're assuming that the Sun gobbled up most of the heavier elements when our solar system was forming.
  • by JustOK ( 667959 )

    They took all the lithium for their laptop batteries.

  • Or possibly strip-mined for the Lithium?

  • You know. you're a bit less than a real star. You may think you're a star but you're not.

  • They found a new star and they didn't even make a wish?! Sheesh! Whimsy is dead...

  • It is probably safer to say that they did not detect lithium in the star's atmosphere.

    The light that we see from a star tends to fit a blackbody curve, which says a lot about the temperature of a star but nothing about the composition. However, the stellar atmosphere will contain absorption or emission lines that tell us about the composition of the atmosphere. It doesn't say anything about the interior of the star.

    Now my recollections of stellar models is quite hazy, but I do recall that different proces

  • "The only elements created shortly after the Big Bang were lithium, hydrogen and helium".

    Wow. I can't believe people actually say this stuff. And from the looks of it, they believe it.

    • Why? The quantities of heavy atoms made in the original big bang nucleosynthesis are widely accepted to have been miniscule. Non-trivial quantities of elements heavier than beryllium didn't exist until stellar nucleosynthesis started. And beryllium itself was produced in such hilariously tiny amounts that it's usually forgotten.

      • By mass, the amounts of lithium and beryllium created during BBNS should be around the same order of magnitude. That may be very small, but nevertheless, the quote in the OP indicates that ONLY lithium hydrogen and helium were created. If your argument is that the amount of beryllium was so small that you can just pretend it's zero and use absolute language, then "no" lithium was created, either.
        • Yes ok. You are correct. I didn't mention beryllium. I'm not an astronomer or an astrophysicist but my impression is that the beryllium created was primarily in unstable isotopes like Beryllium-7 which have such a short half-lives that it would all decay before star formation even got started. Is that correct? If so, then this really doesn't matter for star formation issues. Although yes for technical accuracy I it probably would have been better to say something like "the only stable elements" or something
  • "Astronomers Find Unusual Star"

    That's not surprising, I mean with all the reality shows we have these days...

  • If so, then it could be the exhaust plume of a Bussard Ramjet.

    Oops! Sorry! Wrong reality...

  • Wow, what is so unusual, you think you know what a star is made up of, especially when you can just take a sample and test it right there and then,
    not we have been hypothesizing at all here....

    If we really knew what a star was made up of, then I would agree, however, the fact is we still have yet to be able to take real samples, and even so,
    we should not think that all stars are the same, or even that we have come across all possible star types.....

    Just another day in space continuum for me....

  • The article makes it seem that start formation requires the presence of heavier elements (besides lithium) for a star to form, but aren't heavier elements (besides lithium) only formed within stars?

    • by shoor ( 33382 )

      I'm not an anstronomer either, but the article summary did specifically say small star. The wikipedia article on red dwarfs mentions that as of 2009 there is a 'mystery' as to the absence of red dwarfs with no metals, and the preferred explanation is that without metals only large stars can form. So that theory allows for the bigger stars forming, creating heavier elements, and then exploding, spewing those elements out into the universe. Even if red dwarfs had been created at the beginning, they are

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