Giant cosmic tsunami wakes up comatose galaxies

Galaxies are often found in clusters, which contain many 'red and dead' members that stopped forming stars in the distant past. Now an international team of astronomers have discovered that these comatose galaxies can sometimes come back to life. If clusters of galaxies merge, a huge shock wave can drive the birth of a new generation of stars -- the sleeping galaxies get a new lease of life.

http://www.sciencedaily.com