July 25, 2007 | David F. Coppedge

Stars Found Almost as Old as Universe

A new record was set by a Caltech team using the Keck telescopes on Hawaii: they detected a galaxy nearly as old as the universe.  The consensus age for the universe is 13.6 billion years.  The light from this galaxy, they claim, is over 13 billion years old – “a mere 500 million years after the Big Bang” itself was supposed to have brought the universe into being.  The discovery was reported by the BBC News based on a paper in the Astrophysical Journal.1
    Some astronomers are questioning the accuracy of the report and its use of gravitational lensing to see the distorted light from the distant galaxy, but agree the work was done carefully.  This exceeds the previous redshift record (z = 6.96) into the 8 to 10 range.  The authors found six candidates and proposed that at least two of them are real, and may lie at redshifts close to or beyond z=10.  They assumed metallicities of 1/20 solar abundance.  This means that heavy elements (metals) would have had to be products of a prior generation of hydrogen stars.  The authors also believed that their candidate galaxies were representative of a large abundance of similar low-luminosity galaxies that were present in that epoch.


1Stark, Ellis et al, “A Keck Survey for Gravitationally Lensed Lyman-Alpha Emitters in the Redshift Range 8.5 < z < 10.4: New Constraints on the Contribution of Low-Luminosity Sources to Cosmic Reionization,” The Astrophysical Journal, 663:10-28, 2007 July 1.

These measurements are indirect and tentative.  Confirmation must await observations from the refurbished Hubble, the James Webb Space Telescope, and refinements of the gravitational lensing technique.  There is also a fuzzy line between observation and theory in cases such as these.  Even using their own assumptions, however, the situation is paralleled by that in biology: more maturity and complexity as far back as they can see.

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Categories: Astronomy, Cosmology, Physics

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