Friday, August 2, 2013

ScienceDaily: Galaxies News

ScienceDaily: Galaxies News


Monster galaxies lose their appetite with age

Posted: 01 Aug 2013 04:57 PM PDT

Our universe is filled with gobs of galaxies, bound together by gravity into larger families called clusters. Lying at the heart of most clusters is a monster galaxy thought to grow in size by merging with neighboring galaxies, a process astronomers call galactic cannibalism. New research from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) is showing that, contrary to previous theories, these gargantuan galaxies appear to slow their growth over time, feeding less and less off neighboring galaxies.

When galaxies switch off: Hubble's COSMOS survey solves 'quenched' galaxy mystery

Posted: 01 Aug 2013 06:54 AM PDT

Some galaxies hit a point in their lives when their star formation is snuffed out, and they become "quenched". Quenched galaxies in the distant past appear to be much smaller than the quenched galaxies in the Universe today. This has always puzzled astronomers -- how can these galaxies grow if they are no longer forming stars? A team of astronomers has now used a huge set of Hubble observations to give a surprisingly simple answer to this long-standing cosmic riddle.

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