6degrees AstroBlog

Astronomy News from London Meeting

By Irwin Horowitz, 7-12-07

	A Hubble Space Telescope image released by the W.M. Keck Observatory on July 10, 2007 shows cluster fields with distant galaxy sources marked with circles. Each foreground cluster of galaxies acts as a natural telescope with particularly strong magnification along the 'critical lines' indicated here with black curves. (Caltech/D. Stark/J. Richard/R. Ellis/Handout/Reuters)

While attending a meeting of the Royal Astronomical Society in London, astronomers from Caltech announced yesterday that they have observed some of the most distant galaxies ever detected.  Using one of the twin 10-meter Keck telescopes located at the summit of Mauna Kea on the Big Island of Hawaii, Professor Richard Ellis and graduate student Dan Stark reported that the light they measured left the host galaxies over 13 billion years ago, when our universe was only about 500 million years old.

This light may very well have come from the first generation of stars to form in the infancy of our universe.  The standard model of the Big Bang predicts that after the first few minutes, space was filled with a mixture of free electrons and simple nuclei containing protons and neutrons.  Free electrons are very good at scattering light, so during this time our universe was highly opaque and very bright.  After about 300,000 years, the expanding universe cooled sufficiently for simple atoms to form, as the electrons became bound to the nuclei.  When those electrons were bound up, space became transparent and very dark.  It wasn’t until this first generation of stars had formed that light once again shone forth across the universe.

Even the largest optical telescope in the world would not have been sufficient to make these observations had there not been an intervening massive cluster of galaxies along the observed line of sight.  Such clusters are known to act like a massive magnifying lens, as their gravity bends and intensifies the light from more distant objects.  This “gravitational lens” effect resulted in enough magnification of the brightness of these objects to permit them to be just barely detectable by the telescope.

It is believed that such observations provide vital clues towards understanding the origins of stars and galaxies in the early universe.

In other news from the London meeting:

British and Swiss researchers presented strong evidence that variability in our Sun is not a major factor in the current episode of global climate change.  Mike Lockwood and Claus Froehlich studied a range of factors and concluded that if anything, there should be a decrease in average global temperatures based on solar variations over the past two decades.

European astronomers announced the discovery of an extrasolar planet with strong evidence of water vapor present in its atmosphere.  The planet, known as HD 189733b, circles a star in the constellation of Vulpecula located about 60 light years from our solar system.

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