Galaxies siphoning off hydrogen!

I thought this was an interesting read. There's a pair of two galaxies that seemed to have a river of hydrogen flowing from one to the other. But there is a hypothesis that this could actually be the reason for major star formation in spiral galaxies and how they keep up the pace in star formation. Larger ones effectively siphon off this hydrogen, cold and diffuse, gas from smaller galaxies. Using the GBT, the Green Bank Telescope, astronomer D.J Pisano found the filament of tenuous gas using its immense single dish, unblocked aperture, and its location in the national radio quiet zone. There is also another theory in which this galaxy had a close encounter with its neighbor and the filament is just a ribbon of neutral atomic hydrogen. If this is the case, then there should be stars in this ribbon. Further study will enable astronomers to get a better idea of galaxy evolution.

Credit: D.J. Pisano (WVU); B. Saxton (NRAO/AUI/NSF); Palomar Observatory -- Space Telescope Science Institute 2nd Digital Sky Survey (Caltech); Westerbork Synthesis Radio Telescope
Source: http://phys.org/news/2014-01-river-hydrogen-space-green-bank.html#jCp