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Space Science

New Class of Stars Are Totally Metal, Says Astrophysicist 119

Posted by samzenpus
from the hit-the-lights dept.
KentuckyFC writes Stars form when clouds of gas and dust collapse under their own gravity, generating enough heat and pressure to fuse the atoms inside them together. When this cloud of dust and gas is the remnants of a supernova, it can contain all kinds of heavy elements in addition to primordial hydrogen, helium and lithium. Now one astrophysicist has calculated that a recently discovered phenomenon of turbulence, called preferential concentration, can profoundly alter star formation. He points out that turbulence is essentially vortices rotating on many scales of time and space. On certain scales, the inertial forces these eddies create can push heavy particles into the calmer space between the vortices, thereby increasing their concentration. In giant clouds of interstellar gas, this concentrates heavy elements, increasing their gravitational field, attracting more mass and so on. The result is the formation of a star that is made entirely of heavy elements rather than primordial ones. Astrophysicists call the amount of heavy elements in a star its "metallicity". Including preferential concentration in the standard model of star formation leads to the prediction that 1 in 10,000 stars should be totally metal. Now the race is on to find the first of this new class of entirely metal stars.
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New Class of Stars Are Totally Metal, Says Astrophysicist

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  • by Anonymous Coward on Thursday July 03, 2014 @06:42PM (#47380281)

    or Kerrang! They're full of metal stars

  • by Guy From V (1453391) on Thursday July 03, 2014 @06:42PM (#47380283) Homepage

    When did Nathan Explosion become an astrophysicist?

  • by tomhath (637240) on Thursday July 03, 2014 @06:45PM (#47380301)
    First metal star should be named after them.
  • Wow - a new low in poorly written summaries, sorry.
    • Are you kidding? This isn't even in the lower quartile of bad summaries here. If it were among the worst of the summaries, you wouldn't even know TFA had something to do with stars.
  • Every time I hear about a (cool) new kind of star like this i get all teh happi feelz

    It reminds me of the Cosmos where Sagan elucidates how everything and everyone we've ever known is made of "star stuff" & our composition reflects our star's composition

    So...what kind of planets & planetoids would a **METAL STAR** make???

  • by Guano_Jim (157555) on Thursday July 03, 2014 @06:54PM (#47380369)

    ... they're called Class \m/ stars.

    • I'd say all we need to do to find the Metal stars is to look for those that have their fusion output turned up to 11.

  • by Anonymous Coward

    That totally rocks!!!!

  • by pla (258480) on Thursday July 03, 2014 @07:05PM (#47380439) Journal
    Let's take TFA at face value, and assume one in 10k stars start their evolution as count as "metallic" stars.

    Hydrogen main sequence stars burn for a a few million years (for the class O supergiants) to literally trillions of years (for the class M all-but-failures). Helium burning, in a star with sufficient mass, lasts between a few hundred thousand to a few dozen million years.

    The subject of TFA starts after helium burning normally finishes - Next on a typical star comes carbon, lasting for only a few hundred years; Then comes neon lasting for a single year, oxygen at half a year, and silicon finishes its run in a single day.

    So whether or not a star begins life with a high concentration of trans-lithium metals, it will have a very, very short lifetime; That one-in-ten-thousand creation ratio therefore reduces to more like one-in-a-trillion among those stars still shining in our nighttime sky.
    • by ArcadeMan (2766669) on Thursday July 03, 2014 @07:08PM (#47380455)

      You're right, heavy metal stars usually have short lifespans.

    • you are assuming that by "metal" they mean iron etc. all the examples that you cite (except H and He) are "metals" by astrophysicists' definition.
    • I know very little of astronomy, but I have to wonder at the reason why each of the fusion cyles is shorter... is it only because some intrinsic property of the heavier fuel? I had alsways assumed that the fact that there is only a fraction of the original star mass that makes it to Carbon, and only a fraction of that to each successive element in the list what the root cause the the exponential decay in life expectancy of each fuel source. If that is the case, the reason that each cycle is shorter is the l

      • by kenwd0elq (985465) <kenwd0elq@gmail.com> on Thursday July 03, 2014 @08:55PM (#47380913)

        Fusion of hydrogen into helium produces a LOT of energy. Fusion of helium into carbon produces less. In physics terms, it's the "packing fraction" curve, which can show you what energy you'd get out if you fuse elements together.

        Iron is at the bottom of the packing fraction curve; when you fuse other stuff into iron, you're getting out the dregs of the fusion energy, partly because it takes higher and higher pressures and temperatures for fusion to occur for heavier elements.

        When you get to the pressure and temperature points where iron fuses into still heavier elements, it begins to EXTRACT energy - from the core of the star. Stars exist in a delicate balance between the heat and pressure that tries to blow them apart, and the gravity that tries to crush them together. Take heat OUT of the core of the star, and there's less internal pressure - and gravity starts to win. The core will collapse, generally abruptly, and a crushing "rebound effect" will accelerate the heavy fusion, extracting MORE energy, leading to a core collapse supernova. The star explodes, leaving a black hole or pulsar at the center and blasting a lot of the stellar material back into space.

        Which is where we got the iron for our blood, or the gold for our jewelry - blasted out of a supernova. Probably MANY of them.

        • By the way nickel 62 is the ultimate symbol of death, the atom with the most binding energy per nucleon, and not Iron. I had a job where I extracted cobalt from nickel, and I was thinking this is how the world is gonna end, extracting high energy stuff from the low energy nickel 62 waste. Iron 56 is often cited instead of nickel 62, and it's close in binding energy, but not top, and more abundant because of units of 4, alpha radiation of helium atoms predominate as a unit in building up heavier elements, an
          • Actually the http://en.wikipedia.org/wiki/N... [wikipedia.org] wikipedia page says, even though highest binding energy of all known nuclides per nucleon, Ni 62 per se is very rare, even amongst nickel, because of the difficulty of producing it by neutron capture. Fe 56 has the lowest mass per nucleon, and this whole thing is not a contradiction (lowest mass meaning lowest total energy, or highest binding energy) because when counting nucleons we confuse/confound neutrons with protons. Ni 62 contains a higher ratio of neutr
            • Also, suppose there was a big bang, and all matter started out as hydrogen at 3 K temperature. What's the equilibrium temperature when all the hydrogen is converted to Ni 62 or Fe 56? It's certainly no longer 3K, unless the conservation of energy does not stand. If there is such a thing as thermal heat death of the Universe as predicted by Thompson, (Lord Kelvin) and the 2nd law of thermodynamics, this equilibrium heat death may be of a very hot temperature, at which not the most stable nuclide would releas
      • by Draugo (1674528)
        What kenwd0olq said. If you want somewhat more detailed explanation listen to Richard Pogge's excellent Astronomy 162 lecture series and specifically the lectures about death of low and high mass stars (might be somewhere around lectures 14 and 15 but that's just from memory and I'm not sure about that at all).
  • by jcochran (309950) on Thursday July 03, 2014 @07:12PM (#47380471)

    What astronomers mean for the word "metal" isn't what the rest of us mean.

    As mentioned in the link to Metallicity, the all metal stars could be composed of carbon, nitrogen, oxygen, etc. Basically anything other than hydrogen and helium.

  • Doesn't seem that far fetched when you consider hydrogen is a metal....
  • At first I thought this was about Justin Bieber.

  • by vanyel (28049)

    Now that's heavy metal I could actually get into...

  • Um.. but no energy could be released from such a star surely, since fusion of anything heavier than iron produces no energy, but actually takes energy. The only way it could produce energy then would be fission. But I'm skeptical about whether a star in such circumstances would really light up, or would just be a sphere of dead metal.

    • by gstoddart (321705)

      Um.. but no energy could be released from such a star surely, since fusion of anything heavier than iron produces no energy

      Right, iron Fe, atomic mass 26.

      Lithium, for instance, has an atomic mass of 3. Lithium is a metal. I'm sure there are other metals below 26, Sodium comes to mind (atomic mass of 11).

      So, based on the assumption that heavier than iron means fission, but less than iron fusion, there's still room for fusion, no?

      I think this is fusion, but with a slightly different chemistry, but then the

      • by kenwd0elq (985465)

        In fact, the fusion of anything that produces an element heavier than iron will extract energy from the star's core, hastening its collapse.

      • Wow, a Lithium powered sun, that's pretty cool. :-P

        It sure as hell wouldn't be depressed.

  • Let's not confuse extreme metallicity [wikipedia.org] (the rare star containing nearly zero hydrogen or helium) with an all-metal body [wikipedia.org].
  • Unless it's made of a light metal...then we'll name it Warrant.

  • by arcctgx (607542) on Thursday July 03, 2014 @08:18PM (#47380767)

    If I'm reading TFA correctly, it basically means that stars formed from one molecular cloud have very different metallicities - anywhere between the mean metallicity of the molecular cloud and the "purely metal" extreme. If this is actually true, there may be far reaching implications for the research of stellar clusters. One of the basic assumptions in this field is that all cluster stars created from a given molecular cloud have very similar chemical compositions.

  • by kenwd0elq (985465) <kenwd0elq@gmail.com> on Thursday July 03, 2014 @08:44PM (#47380867)

    In astrophysics, the term "metal" normally applies to any element heavier than lithium. Carbon, silicon, even gasses like oxygen and nitrogen, are "metals". We're not talking about star remnants that are primarily iron or lead or uranium. Gold would be right out.

  • See, there is a God! The Universe is a gigantic Pinball machine and He has just unlocked a Super Multi-ball!
  • And we have been studying stellar spectra for a century now. The must be much rarer than 1 in 10,000 or we would have already found one. They must be exceedingly rare.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      How would you spot them? The stellar spectra you mention are visible because of all the energy that a non-metallic star can generate through fusion. But metal stars don't have that energy available. They'll be dim, which affects the distance at which we can spot them. The lack of light also complicates our ability to determine their spectra. So the fraction of metal stars amongst the stars with a known spectrum will be even lower than that 1:10000.

  • My heart's an iron fist ... http://www.youtube.com/watch?v... [youtube.com]
  • I expected the astrophysicist to be Queen guitarist Brian May...

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