Galaxies are the ultimate recyclers, NASA's Hubble confirms

ScienceDaily (Nov. 17, 2011) — Galaxies learned to "go green" early in the history of the universe, continuously recycling immense volumes of hydrogen gas and heavy elements to build successive generations of stars stretching over billions of years.This ongoing recycling keeps galaxies from emptying their "fuel tanks" and therefore stretches out their star-forming epoch to over 10 billion years. However, galaxies that ignite a rapid firestorm of star birth can blow away their remaining fuel, essentially...

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Astronomers pin down galaxy collision rates by comparing Hubble images to supercomputer simulations

ScienceDaily (Oct. 27, 2011) — A new analysis of images from the Hubble Space Telescope combined with supercomputer simulations of galaxy collisions has cleared up years of confusion about the rate at which smaller galaxies merge to form bigger ones. This paper, led by Jennifer Lotz of Space Telescope Science Institute, is about to be published in The Astrophysical Journal.Galaxies grow mostly by acquiring small amounts of matter from their surroundings. But occasionally galaxies merge with other...

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Astronomers pin down galaxy collision rate with Hubble data

ScienceDaily (Oct. 27, 2011) — A new analysis of Hubble surveys, combined with simulations of galaxy interactions, reveals that the merger rate of galaxies over the last 8 billion to 9 billion years falls between the previous estimates.The galaxy merger rate is one of the fundamental measures of galaxy evolution, yielding clues to how galaxies bulked up over time through encounters with other galaxies. And yet, a huge discrepancy exists over how often galaxies coalesced in the past. Measurements...

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