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How new are carbon chem and rocky planets?

  1. May 24, 2012 #1

    marcus

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    I don't know much about this, only looked into it a bit yesterday. If you know more or can find out something, please contribute.

    Abraham Loeb (eminent Harvard astroph.) says, if I understand him correctly, that light from stars richer in heavy elements than the sun has been observed at redshift z ≥ 6. More specifically, these are stars in the central regions of galaxies which host quasars. That was in 2006: it may have been found more generally, not limited to cores of quasar-host galaxies.

    http://arxiv.org/abs/astro-ph/0604242 See page 3, top of right column. "For example, the cores of quasar host galaxies are known to possess super-solar metallicities at z ≥ 6[91]."

    z=6 means the light has been traveling 12.8 billion years, so was emitted only 0.9 billion years after start of expansion.

    So simply on that basis, rocky planets and carbon chemistry could have existed quite a long time ago. The star-forming clouds of gas were rich enough in heavy elements.

    Loeb points out that this could make sense because the giant stars that cook heavy atoms and blow them out into the surrounding clouds have short lifetimes. You could have several generations of supernovae successively enrich the chemistry of the clouds within a few hundred million years.

    Loeb points out that the environment was denser back then, by a factor of (z+1)3, which would tend to speed up star-formation. He didn't spell it out but one can imagine a supernova chain reaction where one SN makes shockwaves in the gas which nucleate contraction and trigger formation of other giant stars, that then go SN themselves, repeating the process. At redshift z = 9 we are talking about conditions that are 1000 times denser on average.

    So it kind of makes sense that there could have been at least some regions in some galaxies back then that had metal-rich stars. Maybe only certain parts of certain galaxies, but still...

    So carbon chemistry on rocky worlds is not so new? You mean something could have been playing the violin 12.8 billion years ago? We aren't the first to make instruments that cause the local atmosphere to vibrate at definite frequencies? Something else could have plucked a string or blown a flute so long ago?
     
    Last edited: May 24, 2012
  2. jcsd
  3. May 24, 2012 #2
    A thread just closed asked an interesting question about carbon life, starting with

    "we live at the beginning of the time when life is possible"

    https://www.physicsforums.com/showthread.php?t=608410

    Your post provided a possible answer. I just KNEW I should have questioned the 3 generations, 9 billion years idea, and I thought about it, but naively thought "well all galaxies seem more or less the same...." so I lacked a reason.....and forgot about the higher density of the past....

    Not so crazy....but you might find this a crazy addendum: have you ever seen episodes of "Ancient Astronauts"??? on History, or Discovery, or one of the US cable channels...the pictograms of the Aztecs, Incas, Eqyptians, and Sumerian predecessors [forget the correct name, present day Iraq] are amazingly similar, possibly depict space suits and headgear and hoses eerily similar to modern day astronaut wear, flying objets with flames emerging from one end from which 'gods' emerged, and even a primitive tribe in Africa has knowledge of a double star system [supposedly handed down to them by 'gods' who may have had local knowledge of that star system]...that double star system had not been discovered by modern astronomy until many years after explorers got the scoop from tribesman!!! ....some also think signs laser type cutting tools for pyramids, walls, and other temples are evident among the ancient cultures....so there may be some speculative evidence for such "ancient violin playing' right here on earth....

    [I have the distinctly uncomfortable feeling the censors will get me for this post although I'm unsure why!!!]
     
    Last edited: May 24, 2012
  4. May 24, 2012 #3

    marcus

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    Naty you should be keel-hauled for mentioning Ancient Visitors. :tongue: The harmonic oscillator is just about the simplest thing in physics and it stands to reason that any rocky planet with carbon chemistry and an atmosphere would develop simple harmonic oscillators! :biggrin: :wink: :biggrin:
    As long as there is an atmosphere to vibrate, something will make music! Whether it looks like a cricket or like name-your-favorite-band. I just wanted something concrete to visualize when I said rockyplanet carbonchemistry life.
     
    Last edited: May 24, 2012
  5. May 24, 2012 #4

    marcus

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    Anyway, it's interesting that as of 2006 Abraham Loeb would conjecture that metal-rich stars go back a long ways. I'm hoping to hear more about this. Somebody may have more recent news. Has his idea been opposed? Have the observations he cites been questioned?
    Or conversely, have more metal-rich stars been seen at z > 6?

    BTW Loeb is a highly regarded scientist with over 300 publications and high lifetime citations. Kind of astrophysicist you especially want to listen to. I think the evidence in 2006 was slender, more work was needed. He raised all sorts of side issues, like about rates of planet formation under those earlier conditions, and so on. Would having too many stars close together (whether metal-rich or not) disrupt orbits and thus be inimical to life? There ought to be more literature on this.
     
    Last edited: May 24, 2012
  6. May 24, 2012 #5
    heh,heh, good one.......but not so fast...

    Only if I had mentioned CHARIOTS OF THE GODS, which I did NOT mention and will not mention!!!
     
  7. May 25, 2012 #6
    I feel better having skimmed the Loeb paper...Some of his observations make my Ancient Aliens [the term I should have used] comments seem rather demure:

    good luck with that!!
     
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