Processes of Star Formation Associated With Amount of Free Gas in Galaxies

The Herschel infrared space observatory has discovered that galaxies do not always need to collide with each other to drive vigorous star birth. The intensive processes of star formation are associated with the amount of free gas in the galaxies. The finding overturns a long-held assumption and paints a more stately picture of how galaxies evolve. According to Lee Armus, a co-author of the new study from NASA’s Herschel Science Center   at   the   California   Institute of Technology in Pasadena galaxy    mergers    play    an important role in producing the most powerful starbursts today. 

But in the early universe, when most galaxies contained a lot more gas, mergers were not the only way, or even the most common way, to make lots of stars at a rapid rate.  The new results are based on Herschel’s observations of two patches of sky, each about one-third the size of the full moon.
source:www.nasa.gov