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Age and metallicity of Population I stars?

  1. Dec 4, 2008 #1
    I did some research in regards to the age and metallicity of population I stars in hopes to come up with a novel solution to the Fermi Paradox. Anyways, while the metallicity of the oldest Population I stars can be tracked down to be something like -1 (10% of that of the sun) determining the age of the oldest Population I stars was a bit more tricky - or put another way: nada! :-)

    What I am looking for is (ideally) the distribution curve of the age of Population I stars (in the Milky way and possibly outside) and their respective average metallicity (again ideally for the different metals).

    For an interesting paper titled "Occurrence of Planets Correlates with Stellar Metalicity" see http://exoplanets.org/metalicity.html

    For a paper coming to the exact opposite results when it comes to stars with close companions see http://sci.tech-archive.net/Archive/sci.astro/2007-11/msg00135.html
     
    Last edited: Dec 4, 2008
  2. jcsd
  3. Dec 5, 2008 #2
    Welcome to the Forum! First off, the survey of stars you reference is from 2004. There are currently 280 stars known to have planets:
    http://planetquest.jpl.nasa.gov/atlas/atlas_index.cfm
    This is a calculator search engine with metallicity:
    http://nsted.ipac.caltech.edu/cgi-bin/Sieve/nph-sieve?mission=NStED&currentForm=Home&nextForm=Basic
    This is an online walkthrough of stellar evolution that might be of help:
    http://astronomyonline.org/Stars/Populations.asp

    As you probably know, huge gas clouds of hydrogen collapse into a cluster of stars. Huge stars within this cluster form rapidly from the hydrogen and are thus Population II stars. These giants fuse hydrogen into heavier elements (referred to as “metals”, although these are any elements heavier than hydrogen) and then explode after only a few million years, seeding the surrounding cluster with many solar mass equivalents of these metals. The cluster continues to form stars, some like our Sun that are much smaller and thus exist for billions of years. These stars collect the metals along with the hydrogen of the cluster and thus become Population I stars with a high metallicity. However, the terms Population I or II (or even III) are relative to that specific cluster. Pop I stars in an ancient cluster might be billions of years older than a Pop I star in a new cluster, like the Orion Nebula and the metallicity will depend on the number of huge stars that seeded the cluster. So you might find a ten billion year old white dwarf with planets at one point in the galaxy and then a one million year old Type G with higher metallicity, but no planets yet, in another. Since it is logical to assume that all clusters form by the same mechanism, then the Pop I stars should receive the heavier elements necessary for planets (and perhaps life) from the Pop II’s in their cluster. Thus, age and metallicity of Population I stars should average out, i.e., an ancient Pop I could have the same metallicity as a new Pop I.

    As to the Fermi Paradox, the evidence is that there are no Type III civilizations within a billion light years of the Earth, or their Dyson Sphere would be here. :smile:
     
    Last edited: Dec 5, 2008
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